Chapter 5 protein Biosynthesis

Complementary Biochemistry 242 MLT

Gene Expression Transcription

The majority of genes are expressed as the proteins theyencode

The process occurs in two steps

Transcription = DNA rarr RNATranslation = RNA rarr protein

Taken together they make up the central dogma ofbiology

DNArarrRNArarrprotein

bullDNA serves as the template for the synthesis of RNA much as it does for its ownreplicationbull The Stepsbull50 different protein transcription factors bind to promoter sites usually on the 5prime sideof the gene to be transcribedbull An enzyme an RNA polymerase binds to the complex of transcription factorsbull Working together they open the DNA double helixbull The RNA polymerase proceeds to read one strand moving in its 3prime rarr 5prime direction

Gene Transcription DNA rarr RNA

bull In eukaryotes this requires at least for protein‐encoding genes that the nucleosomesin front of the advancing RNA polymerase (RNAP II) be removed A complex of proteinsis responsible for this The same complex replaces the nucleosomes after the DNA hasbeen transcribed and RNAP II has moved on

bullAs the RNA polymerase travels along the DNA strand it assembles ribonucleotides(supplied as triphosphates eg ATP) into a strand of RNAbull Each ribonucleotide is inserted into the growing RNA strand following the rules ofbase pairingbullThus for each C encountered on the DNA strand a G is inserted in the RNA foreach G a C and for each T an A However each A on the DNA guides the insertionof the pyrimidine uracil (U from uridine triphosphate UTP) There is no T in RNAbull

Synthesis of the RNA proceeds in the 5prime rarr 3prime directionbull As each nucleoside triphosphate is brought in to add to the 3prime end of the growingstrand the two terminal phosphates are removedbull When transcription is complete the transcript is released from the polymeraseand shortly thereafter the polymerase is released from the DNA

Messenger RNA (mRNA) This will later be translated into a polypeptideribosomal RNA (rRNA) used in the building of rRNA) ribosomes machinery for synthesizing proteinsby translating mRNATransfer RNA (tRNA) RNA molecules that carry amino acids to the growing polypeptideSmall nuclear RNA (snRNA) DNA transcription of the genes for mRNA rRNA and tRNAproduces large precursor molecules (primary transcripts) that must be processed within thenucleus to produce the functional molecules for export to the cytosol

Types of RNA

Small nucleolar RNA (snoRNA) These RNAs within the nucleolus have several functions

MICRORNA (miRNA) These are tiny (~22 nts) RNA molecules that appear to regulate theexpression of messenger RNA (mRNA) moleculesXIST RNA This inactivates one of the two X chromosomes in female vertebrates

Types of RNA

Messenger RNA (mRNA)Messenger RNA comes in a wide range of sizes reflecting the size of thepolypeptide it encodes Most cells produce small amounts of thousandsof different mRNA molecules each to be translated into a peptideneeded by the cellMany mRNAs are common to most cells encoding housekeepingproteins needed by all cells (eg the enzymes of glycolysis) OthermRNAs are specific for only certain types of cells These encode proteinsneeded for the function of that particular cell (eg the mRNA forhemoglobin in the precursors of red blood cells)

Ribosomal RNA (rRNA)bullThere are 4 kinds In eukaryotes these are 18S rRNA One of these moleculesalong with some 30 different protein molecules is used to make the small subunitof the ribosomebull 28S 58S and 5S rRNA One each of these molecules along with some 45different proteins are used to make the large subunit of the ribosomebull The S number given each type of rRNA reflects the rate at which the moleculessediment in the ultracentrifuge The larger the number the larger the molecule(but not proportionally)

bull The 28S 18S and 58S molecules are produced by the processing of a singleprimary transcript from a cluster of identical copies of a single gene The 5Smolecules are produced from a different cluster of identical genes

Transfer RNA (tRNA)bullThere are some 32 different kinds of tRNA in a typical eukaryotic cell Each is theproduct of a separate genebull They are small (~4S) containing 73‐93 nucleotidesbull Many of the bases in the chain pair with each other forming sections of doublehelixbull The unpaired regions form 3 loopsbull Each kind of tRNA carries (at its 3prime end) one of the 20 amino acids (thus mostamino acids have more than one tRNA responsible for them)bull At one loop 3 unpaired bases form an anticodonbull Base pairing between the anticodon and the complementary codon on a mRNAmolecule brings the correct amino acid into the growing polypeptide chain

Small Nuclear RNA (snRNA)

bullApproximately a dozen different genes for snRNAs eachpresent in multiple copies have been identifiedbullThe snRNAs have various roles in the processing of the otherclasses of RNAbull For example several snRNAs are part of the spliceosomesthat participate in converting pre‐mRNA into mRNA byexcising the introns and splicing the exons

Small Nucleolar RNA (snoRNA)bullAs the name suggests these small (60ndash300 nts) RNAs are found in the nucleolus wherethey are responsible for several functions Some participate in making ribosomes by helpingto cut up the large RNA precursor of the 28S 18S and 58S moleculesbull Others chemically modify many of the nucleotides in rRNA tRNA and snRNA moleculeseg by adding methyl groups to ribosebull Some have been implicated in the alternative splicing of pre‐mRNA to different forms ofmature mRNAbull One snoRNA serves as the template for the synthesis of telomeresbull In vertebrates the snoRNAs are made from introns removed during RNA processing

Non‐coding RNAbullOnly messenger RNA encodes polypeptides Allthe other classes of RNA including types notmentioned here are thus called non‐codingRNAbullMuch remains to be learned about thefunction(s) of some of thembullBut taken together non‐coding RNAs probablyaccount for two‐thirds of the transcription goingon in the nucleus

The RNA polymerasesbullThe RNA polymerases are huge multi‐subunit protein complexesbull Three kinds are found in eukaryotesbullRNA polymerase I (Pol I) It transcribes the rRNA genes for theprecursor of the 28S 18S and 58S molecules (and is the busiestof the RNA polymerases)bull RNA polymerase II (Pol II also known as RNAP II) It transcribesprotein‐encoding genes into mRNA (and also the snRNA genes)bull RNA polymerase III (Pol III) It transcribes the 5S rRNA genes andall the tRNA genes

The steps of RNA processing

bullSynthesis of the cap This is a modified guanine (G) which is attached to the 5prime end ofthe pre‐mRNA as it emerges from RNA polymerase II (RNAP II)bull The cap protects the RNA from being degraded by enzymes that degrade RNA from the 5primeend serves as an assembly point for the proteins needed to recruit the small subunit of theribosome to begin translationbull Step‐by‐step removal of introns present in the pre‐mRNA and splicing of remainingexons This step takes place as the pre‐mRNA continues to emerge from RNAP II

bull Synthesis of the poly(A) tail This is a stretch of adenine (A) nucleotides When aspecial poly(A) attachment site in the pre‐mRNA emerges from RNAP II the transcriptis cut there and the poly(A) tail is attached to the exposed 3prime endbull This completes the mRNA molecule which is now ready for export to the cytosol (Theremainder of the transcript is degraded and the RNA polymerase leaves the DNA) bullThe removal of introns and splicing of exons is done by

The steps of RNA processing

spliceosomesbullThese are a complexes of 5 snRNA molecules and some145 different proteinsbull The introns in most pre‐mRNAs begin with a GU and endwith an AGbullPresumably these short sequences assist in guiding thespliceosome

Components of Translation

1048766Amino acids1048766The tRNA1048766Aminoacyl-tRNA synthetases1048766The mRNA1048766Competent ribosomes1048766Protein factors1048766ATP and GTP

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

Gene Expression Transcription

The majority of genes are expressed as the proteins theyencode

The process occurs in two steps

Transcription = DNA rarr RNATranslation = RNA rarr protein

Taken together they make up the central dogma ofbiology

DNArarrRNArarrprotein

bullDNA serves as the template for the synthesis of RNA much as it does for its ownreplicationbull The Stepsbull50 different protein transcription factors bind to promoter sites usually on the 5prime sideof the gene to be transcribedbull An enzyme an RNA polymerase binds to the complex of transcription factorsbull Working together they open the DNA double helixbull The RNA polymerase proceeds to read one strand moving in its 3prime rarr 5prime direction

Gene Transcription DNA rarr RNA

bull In eukaryotes this requires at least for protein‐encoding genes that the nucleosomesin front of the advancing RNA polymerase (RNAP II) be removed A complex of proteinsis responsible for this The same complex replaces the nucleosomes after the DNA hasbeen transcribed and RNAP II has moved on

bullAs the RNA polymerase travels along the DNA strand it assembles ribonucleotides(supplied as triphosphates eg ATP) into a strand of RNAbull Each ribonucleotide is inserted into the growing RNA strand following the rules ofbase pairingbullThus for each C encountered on the DNA strand a G is inserted in the RNA foreach G a C and for each T an A However each A on the DNA guides the insertionof the pyrimidine uracil (U from uridine triphosphate UTP) There is no T in RNAbull

Synthesis of the RNA proceeds in the 5prime rarr 3prime directionbull As each nucleoside triphosphate is brought in to add to the 3prime end of the growingstrand the two terminal phosphates are removedbull When transcription is complete the transcript is released from the polymeraseand shortly thereafter the polymerase is released from the DNA

Messenger RNA (mRNA) This will later be translated into a polypeptideribosomal RNA (rRNA) used in the building of rRNA) ribosomes machinery for synthesizing proteinsby translating mRNATransfer RNA (tRNA) RNA molecules that carry amino acids to the growing polypeptideSmall nuclear RNA (snRNA) DNA transcription of the genes for mRNA rRNA and tRNAproduces large precursor molecules (primary transcripts) that must be processed within thenucleus to produce the functional molecules for export to the cytosol

Types of RNA

Small nucleolar RNA (snoRNA) These RNAs within the nucleolus have several functions

MICRORNA (miRNA) These are tiny (~22 nts) RNA molecules that appear to regulate theexpression of messenger RNA (mRNA) moleculesXIST RNA This inactivates one of the two X chromosomes in female vertebrates

Types of RNA

Messenger RNA (mRNA)Messenger RNA comes in a wide range of sizes reflecting the size of thepolypeptide it encodes Most cells produce small amounts of thousandsof different mRNA molecules each to be translated into a peptideneeded by the cellMany mRNAs are common to most cells encoding housekeepingproteins needed by all cells (eg the enzymes of glycolysis) OthermRNAs are specific for only certain types of cells These encode proteinsneeded for the function of that particular cell (eg the mRNA forhemoglobin in the precursors of red blood cells)

Ribosomal RNA (rRNA)bullThere are 4 kinds In eukaryotes these are 18S rRNA One of these moleculesalong with some 30 different protein molecules is used to make the small subunitof the ribosomebull 28S 58S and 5S rRNA One each of these molecules along with some 45different proteins are used to make the large subunit of the ribosomebull The S number given each type of rRNA reflects the rate at which the moleculessediment in the ultracentrifuge The larger the number the larger the molecule(but not proportionally)

bull The 28S 18S and 58S molecules are produced by the processing of a singleprimary transcript from a cluster of identical copies of a single gene The 5Smolecules are produced from a different cluster of identical genes

Transfer RNA (tRNA)bullThere are some 32 different kinds of tRNA in a typical eukaryotic cell Each is theproduct of a separate genebull They are small (~4S) containing 73‐93 nucleotidesbull Many of the bases in the chain pair with each other forming sections of doublehelixbull The unpaired regions form 3 loopsbull Each kind of tRNA carries (at its 3prime end) one of the 20 amino acids (thus mostamino acids have more than one tRNA responsible for them)bull At one loop 3 unpaired bases form an anticodonbull Base pairing between the anticodon and the complementary codon on a mRNAmolecule brings the correct amino acid into the growing polypeptide chain

Small Nuclear RNA (snRNA)

bullApproximately a dozen different genes for snRNAs eachpresent in multiple copies have been identifiedbullThe snRNAs have various roles in the processing of the otherclasses of RNAbull For example several snRNAs are part of the spliceosomesthat participate in converting pre‐mRNA into mRNA byexcising the introns and splicing the exons

Small Nucleolar RNA (snoRNA)bullAs the name suggests these small (60ndash300 nts) RNAs are found in the nucleolus wherethey are responsible for several functions Some participate in making ribosomes by helpingto cut up the large RNA precursor of the 28S 18S and 58S moleculesbull Others chemically modify many of the nucleotides in rRNA tRNA and snRNA moleculeseg by adding methyl groups to ribosebull Some have been implicated in the alternative splicing of pre‐mRNA to different forms ofmature mRNAbull One snoRNA serves as the template for the synthesis of telomeresbull In vertebrates the snoRNAs are made from introns removed during RNA processing

Non‐coding RNAbullOnly messenger RNA encodes polypeptides Allthe other classes of RNA including types notmentioned here are thus called non‐codingRNAbullMuch remains to be learned about thefunction(s) of some of thembullBut taken together non‐coding RNAs probablyaccount for two‐thirds of the transcription goingon in the nucleus

The RNA polymerasesbullThe RNA polymerases are huge multi‐subunit protein complexesbull Three kinds are found in eukaryotesbullRNA polymerase I (Pol I) It transcribes the rRNA genes for theprecursor of the 28S 18S and 58S molecules (and is the busiestof the RNA polymerases)bull RNA polymerase II (Pol II also known as RNAP II) It transcribesprotein‐encoding genes into mRNA (and also the snRNA genes)bull RNA polymerase III (Pol III) It transcribes the 5S rRNA genes andall the tRNA genes

The steps of RNA processing

bullSynthesis of the cap This is a modified guanine (G) which is attached to the 5prime end ofthe pre‐mRNA as it emerges from RNA polymerase II (RNAP II)bull The cap protects the RNA from being degraded by enzymes that degrade RNA from the 5primeend serves as an assembly point for the proteins needed to recruit the small subunit of theribosome to begin translationbull Step‐by‐step removal of introns present in the pre‐mRNA and splicing of remainingexons This step takes place as the pre‐mRNA continues to emerge from RNAP II

bull Synthesis of the poly(A) tail This is a stretch of adenine (A) nucleotides When aspecial poly(A) attachment site in the pre‐mRNA emerges from RNAP II the transcriptis cut there and the poly(A) tail is attached to the exposed 3prime endbull This completes the mRNA molecule which is now ready for export to the cytosol (Theremainder of the transcript is degraded and the RNA polymerase leaves the DNA) bullThe removal of introns and splicing of exons is done by

The steps of RNA processing

spliceosomesbullThese are a complexes of 5 snRNA molecules and some145 different proteinsbull The introns in most pre‐mRNAs begin with a GU and endwith an AGbullPresumably these short sequences assist in guiding thespliceosome

Components of Translation

1048766Amino acids1048766The tRNA1048766Aminoacyl-tRNA synthetases1048766The mRNA1048766Competent ribosomes1048766Protein factors1048766ATP and GTP

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

bullDNA serves as the template for the synthesis of RNA much as it does for its ownreplicationbull The Stepsbull50 different protein transcription factors bind to promoter sites usually on the 5prime sideof the gene to be transcribedbull An enzyme an RNA polymerase binds to the complex of transcription factorsbull Working together they open the DNA double helixbull The RNA polymerase proceeds to read one strand moving in its 3prime rarr 5prime direction

Gene Transcription DNA rarr RNA

bull In eukaryotes this requires at least for protein‐encoding genes that the nucleosomesin front of the advancing RNA polymerase (RNAP II) be removed A complex of proteinsis responsible for this The same complex replaces the nucleosomes after the DNA hasbeen transcribed and RNAP II has moved on

bullAs the RNA polymerase travels along the DNA strand it assembles ribonucleotides(supplied as triphosphates eg ATP) into a strand of RNAbull Each ribonucleotide is inserted into the growing RNA strand following the rules ofbase pairingbullThus for each C encountered on the DNA strand a G is inserted in the RNA foreach G a C and for each T an A However each A on the DNA guides the insertionof the pyrimidine uracil (U from uridine triphosphate UTP) There is no T in RNAbull

Synthesis of the RNA proceeds in the 5prime rarr 3prime directionbull As each nucleoside triphosphate is brought in to add to the 3prime end of the growingstrand the two terminal phosphates are removedbull When transcription is complete the transcript is released from the polymeraseand shortly thereafter the polymerase is released from the DNA

Messenger RNA (mRNA) This will later be translated into a polypeptideribosomal RNA (rRNA) used in the building of rRNA) ribosomes machinery for synthesizing proteinsby translating mRNATransfer RNA (tRNA) RNA molecules that carry amino acids to the growing polypeptideSmall nuclear RNA (snRNA) DNA transcription of the genes for mRNA rRNA and tRNAproduces large precursor molecules (primary transcripts) that must be processed within thenucleus to produce the functional molecules for export to the cytosol

Types of RNA

Small nucleolar RNA (snoRNA) These RNAs within the nucleolus have several functions

MICRORNA (miRNA) These are tiny (~22 nts) RNA molecules that appear to regulate theexpression of messenger RNA (mRNA) moleculesXIST RNA This inactivates one of the two X chromosomes in female vertebrates

Types of RNA

Messenger RNA (mRNA)Messenger RNA comes in a wide range of sizes reflecting the size of thepolypeptide it encodes Most cells produce small amounts of thousandsof different mRNA molecules each to be translated into a peptideneeded by the cellMany mRNAs are common to most cells encoding housekeepingproteins needed by all cells (eg the enzymes of glycolysis) OthermRNAs are specific for only certain types of cells These encode proteinsneeded for the function of that particular cell (eg the mRNA forhemoglobin in the precursors of red blood cells)

Ribosomal RNA (rRNA)bullThere are 4 kinds In eukaryotes these are 18S rRNA One of these moleculesalong with some 30 different protein molecules is used to make the small subunitof the ribosomebull 28S 58S and 5S rRNA One each of these molecules along with some 45different proteins are used to make the large subunit of the ribosomebull The S number given each type of rRNA reflects the rate at which the moleculessediment in the ultracentrifuge The larger the number the larger the molecule(but not proportionally)

bull The 28S 18S and 58S molecules are produced by the processing of a singleprimary transcript from a cluster of identical copies of a single gene The 5Smolecules are produced from a different cluster of identical genes

Transfer RNA (tRNA)bullThere are some 32 different kinds of tRNA in a typical eukaryotic cell Each is theproduct of a separate genebull They are small (~4S) containing 73‐93 nucleotidesbull Many of the bases in the chain pair with each other forming sections of doublehelixbull The unpaired regions form 3 loopsbull Each kind of tRNA carries (at its 3prime end) one of the 20 amino acids (thus mostamino acids have more than one tRNA responsible for them)bull At one loop 3 unpaired bases form an anticodonbull Base pairing between the anticodon and the complementary codon on a mRNAmolecule brings the correct amino acid into the growing polypeptide chain

Small Nuclear RNA (snRNA)

bullApproximately a dozen different genes for snRNAs eachpresent in multiple copies have been identifiedbullThe snRNAs have various roles in the processing of the otherclasses of RNAbull For example several snRNAs are part of the spliceosomesthat participate in converting pre‐mRNA into mRNA byexcising the introns and splicing the exons

Small Nucleolar RNA (snoRNA)bullAs the name suggests these small (60ndash300 nts) RNAs are found in the nucleolus wherethey are responsible for several functions Some participate in making ribosomes by helpingto cut up the large RNA precursor of the 28S 18S and 58S moleculesbull Others chemically modify many of the nucleotides in rRNA tRNA and snRNA moleculeseg by adding methyl groups to ribosebull Some have been implicated in the alternative splicing of pre‐mRNA to different forms ofmature mRNAbull One snoRNA serves as the template for the synthesis of telomeresbull In vertebrates the snoRNAs are made from introns removed during RNA processing

Non‐coding RNAbullOnly messenger RNA encodes polypeptides Allthe other classes of RNA including types notmentioned here are thus called non‐codingRNAbullMuch remains to be learned about thefunction(s) of some of thembullBut taken together non‐coding RNAs probablyaccount for two‐thirds of the transcription goingon in the nucleus

The RNA polymerasesbullThe RNA polymerases are huge multi‐subunit protein complexesbull Three kinds are found in eukaryotesbullRNA polymerase I (Pol I) It transcribes the rRNA genes for theprecursor of the 28S 18S and 58S molecules (and is the busiestof the RNA polymerases)bull RNA polymerase II (Pol II also known as RNAP II) It transcribesprotein‐encoding genes into mRNA (and also the snRNA genes)bull RNA polymerase III (Pol III) It transcribes the 5S rRNA genes andall the tRNA genes

The steps of RNA processing

bullSynthesis of the cap This is a modified guanine (G) which is attached to the 5prime end ofthe pre‐mRNA as it emerges from RNA polymerase II (RNAP II)bull The cap protects the RNA from being degraded by enzymes that degrade RNA from the 5primeend serves as an assembly point for the proteins needed to recruit the small subunit of theribosome to begin translationbull Step‐by‐step removal of introns present in the pre‐mRNA and splicing of remainingexons This step takes place as the pre‐mRNA continues to emerge from RNAP II

bull Synthesis of the poly(A) tail This is a stretch of adenine (A) nucleotides When aspecial poly(A) attachment site in the pre‐mRNA emerges from RNAP II the transcriptis cut there and the poly(A) tail is attached to the exposed 3prime endbull This completes the mRNA molecule which is now ready for export to the cytosol (Theremainder of the transcript is degraded and the RNA polymerase leaves the DNA) bullThe removal of introns and splicing of exons is done by

The steps of RNA processing

spliceosomesbullThese are a complexes of 5 snRNA molecules and some145 different proteinsbull The introns in most pre‐mRNAs begin with a GU and endwith an AGbullPresumably these short sequences assist in guiding thespliceosome

Components of Translation

1048766Amino acids1048766The tRNA1048766Aminoacyl-tRNA synthetases1048766The mRNA1048766Competent ribosomes1048766Protein factors1048766ATP and GTP

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

bull In eukaryotes this requires at least for protein‐encoding genes that the nucleosomesin front of the advancing RNA polymerase (RNAP II) be removed A complex of proteinsis responsible for this The same complex replaces the nucleosomes after the DNA hasbeen transcribed and RNAP II has moved on

bullAs the RNA polymerase travels along the DNA strand it assembles ribonucleotides(supplied as triphosphates eg ATP) into a strand of RNAbull Each ribonucleotide is inserted into the growing RNA strand following the rules ofbase pairingbullThus for each C encountered on the DNA strand a G is inserted in the RNA foreach G a C and for each T an A However each A on the DNA guides the insertionof the pyrimidine uracil (U from uridine triphosphate UTP) There is no T in RNAbull

Synthesis of the RNA proceeds in the 5prime rarr 3prime directionbull As each nucleoside triphosphate is brought in to add to the 3prime end of the growingstrand the two terminal phosphates are removedbull When transcription is complete the transcript is released from the polymeraseand shortly thereafter the polymerase is released from the DNA

Messenger RNA (mRNA) This will later be translated into a polypeptideribosomal RNA (rRNA) used in the building of rRNA) ribosomes machinery for synthesizing proteinsby translating mRNATransfer RNA (tRNA) RNA molecules that carry amino acids to the growing polypeptideSmall nuclear RNA (snRNA) DNA transcription of the genes for mRNA rRNA and tRNAproduces large precursor molecules (primary transcripts) that must be processed within thenucleus to produce the functional molecules for export to the cytosol

Types of RNA

Small nucleolar RNA (snoRNA) These RNAs within the nucleolus have several functions

MICRORNA (miRNA) These are tiny (~22 nts) RNA molecules that appear to regulate theexpression of messenger RNA (mRNA) moleculesXIST RNA This inactivates one of the two X chromosomes in female vertebrates

Types of RNA

Messenger RNA (mRNA)Messenger RNA comes in a wide range of sizes reflecting the size of thepolypeptide it encodes Most cells produce small amounts of thousandsof different mRNA molecules each to be translated into a peptideneeded by the cellMany mRNAs are common to most cells encoding housekeepingproteins needed by all cells (eg the enzymes of glycolysis) OthermRNAs are specific for only certain types of cells These encode proteinsneeded for the function of that particular cell (eg the mRNA forhemoglobin in the precursors of red blood cells)

Ribosomal RNA (rRNA)bullThere are 4 kinds In eukaryotes these are 18S rRNA One of these moleculesalong with some 30 different protein molecules is used to make the small subunitof the ribosomebull 28S 58S and 5S rRNA One each of these molecules along with some 45different proteins are used to make the large subunit of the ribosomebull The S number given each type of rRNA reflects the rate at which the moleculessediment in the ultracentrifuge The larger the number the larger the molecule(but not proportionally)

bull The 28S 18S and 58S molecules are produced by the processing of a singleprimary transcript from a cluster of identical copies of a single gene The 5Smolecules are produced from a different cluster of identical genes

Transfer RNA (tRNA)bullThere are some 32 different kinds of tRNA in a typical eukaryotic cell Each is theproduct of a separate genebull They are small (~4S) containing 73‐93 nucleotidesbull Many of the bases in the chain pair with each other forming sections of doublehelixbull The unpaired regions form 3 loopsbull Each kind of tRNA carries (at its 3prime end) one of the 20 amino acids (thus mostamino acids have more than one tRNA responsible for them)bull At one loop 3 unpaired bases form an anticodonbull Base pairing between the anticodon and the complementary codon on a mRNAmolecule brings the correct amino acid into the growing polypeptide chain

Small Nuclear RNA (snRNA)

bullApproximately a dozen different genes for snRNAs eachpresent in multiple copies have been identifiedbullThe snRNAs have various roles in the processing of the otherclasses of RNAbull For example several snRNAs are part of the spliceosomesthat participate in converting pre‐mRNA into mRNA byexcising the introns and splicing the exons

Small Nucleolar RNA (snoRNA)bullAs the name suggests these small (60ndash300 nts) RNAs are found in the nucleolus wherethey are responsible for several functions Some participate in making ribosomes by helpingto cut up the large RNA precursor of the 28S 18S and 58S moleculesbull Others chemically modify many of the nucleotides in rRNA tRNA and snRNA moleculeseg by adding methyl groups to ribosebull Some have been implicated in the alternative splicing of pre‐mRNA to different forms ofmature mRNAbull One snoRNA serves as the template for the synthesis of telomeresbull In vertebrates the snoRNAs are made from introns removed during RNA processing

Non‐coding RNAbullOnly messenger RNA encodes polypeptides Allthe other classes of RNA including types notmentioned here are thus called non‐codingRNAbullMuch remains to be learned about thefunction(s) of some of thembullBut taken together non‐coding RNAs probablyaccount for two‐thirds of the transcription goingon in the nucleus

The RNA polymerasesbullThe RNA polymerases are huge multi‐subunit protein complexesbull Three kinds are found in eukaryotesbullRNA polymerase I (Pol I) It transcribes the rRNA genes for theprecursor of the 28S 18S and 58S molecules (and is the busiestof the RNA polymerases)bull RNA polymerase II (Pol II also known as RNAP II) It transcribesprotein‐encoding genes into mRNA (and also the snRNA genes)bull RNA polymerase III (Pol III) It transcribes the 5S rRNA genes andall the tRNA genes

The steps of RNA processing

bullSynthesis of the cap This is a modified guanine (G) which is attached to the 5prime end ofthe pre‐mRNA as it emerges from RNA polymerase II (RNAP II)bull The cap protects the RNA from being degraded by enzymes that degrade RNA from the 5primeend serves as an assembly point for the proteins needed to recruit the small subunit of theribosome to begin translationbull Step‐by‐step removal of introns present in the pre‐mRNA and splicing of remainingexons This step takes place as the pre‐mRNA continues to emerge from RNAP II

bull Synthesis of the poly(A) tail This is a stretch of adenine (A) nucleotides When aspecial poly(A) attachment site in the pre‐mRNA emerges from RNAP II the transcriptis cut there and the poly(A) tail is attached to the exposed 3prime endbull This completes the mRNA molecule which is now ready for export to the cytosol (Theremainder of the transcript is degraded and the RNA polymerase leaves the DNA) bullThe removal of introns and splicing of exons is done by

The steps of RNA processing

spliceosomesbullThese are a complexes of 5 snRNA molecules and some145 different proteinsbull The introns in most pre‐mRNAs begin with a GU and endwith an AGbullPresumably these short sequences assist in guiding thespliceosome

Components of Translation

1048766Amino acids1048766The tRNA1048766Aminoacyl-tRNA synthetases1048766The mRNA1048766Competent ribosomes1048766Protein factors1048766ATP and GTP

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

bullAs the RNA polymerase travels along the DNA strand it assembles ribonucleotides(supplied as triphosphates eg ATP) into a strand of RNAbull Each ribonucleotide is inserted into the growing RNA strand following the rules ofbase pairingbullThus for each C encountered on the DNA strand a G is inserted in the RNA foreach G a C and for each T an A However each A on the DNA guides the insertionof the pyrimidine uracil (U from uridine triphosphate UTP) There is no T in RNAbull

Synthesis of the RNA proceeds in the 5prime rarr 3prime directionbull As each nucleoside triphosphate is brought in to add to the 3prime end of the growingstrand the two terminal phosphates are removedbull When transcription is complete the transcript is released from the polymeraseand shortly thereafter the polymerase is released from the DNA

Messenger RNA (mRNA) This will later be translated into a polypeptideribosomal RNA (rRNA) used in the building of rRNA) ribosomes machinery for synthesizing proteinsby translating mRNATransfer RNA (tRNA) RNA molecules that carry amino acids to the growing polypeptideSmall nuclear RNA (snRNA) DNA transcription of the genes for mRNA rRNA and tRNAproduces large precursor molecules (primary transcripts) that must be processed within thenucleus to produce the functional molecules for export to the cytosol

Types of RNA

Small nucleolar RNA (snoRNA) These RNAs within the nucleolus have several functions

MICRORNA (miRNA) These are tiny (~22 nts) RNA molecules that appear to regulate theexpression of messenger RNA (mRNA) moleculesXIST RNA This inactivates one of the two X chromosomes in female vertebrates

Types of RNA

Messenger RNA (mRNA)Messenger RNA comes in a wide range of sizes reflecting the size of thepolypeptide it encodes Most cells produce small amounts of thousandsof different mRNA molecules each to be translated into a peptideneeded by the cellMany mRNAs are common to most cells encoding housekeepingproteins needed by all cells (eg the enzymes of glycolysis) OthermRNAs are specific for only certain types of cells These encode proteinsneeded for the function of that particular cell (eg the mRNA forhemoglobin in the precursors of red blood cells)

Ribosomal RNA (rRNA)bullThere are 4 kinds In eukaryotes these are 18S rRNA One of these moleculesalong with some 30 different protein molecules is used to make the small subunitof the ribosomebull 28S 58S and 5S rRNA One each of these molecules along with some 45different proteins are used to make the large subunit of the ribosomebull The S number given each type of rRNA reflects the rate at which the moleculessediment in the ultracentrifuge The larger the number the larger the molecule(but not proportionally)

bull The 28S 18S and 58S molecules are produced by the processing of a singleprimary transcript from a cluster of identical copies of a single gene The 5Smolecules are produced from a different cluster of identical genes

Transfer RNA (tRNA)bullThere are some 32 different kinds of tRNA in a typical eukaryotic cell Each is theproduct of a separate genebull They are small (~4S) containing 73‐93 nucleotidesbull Many of the bases in the chain pair with each other forming sections of doublehelixbull The unpaired regions form 3 loopsbull Each kind of tRNA carries (at its 3prime end) one of the 20 amino acids (thus mostamino acids have more than one tRNA responsible for them)bull At one loop 3 unpaired bases form an anticodonbull Base pairing between the anticodon and the complementary codon on a mRNAmolecule brings the correct amino acid into the growing polypeptide chain

Small Nuclear RNA (snRNA)

bullApproximately a dozen different genes for snRNAs eachpresent in multiple copies have been identifiedbullThe snRNAs have various roles in the processing of the otherclasses of RNAbull For example several snRNAs are part of the spliceosomesthat participate in converting pre‐mRNA into mRNA byexcising the introns and splicing the exons

Small Nucleolar RNA (snoRNA)bullAs the name suggests these small (60ndash300 nts) RNAs are found in the nucleolus wherethey are responsible for several functions Some participate in making ribosomes by helpingto cut up the large RNA precursor of the 28S 18S and 58S moleculesbull Others chemically modify many of the nucleotides in rRNA tRNA and snRNA moleculeseg by adding methyl groups to ribosebull Some have been implicated in the alternative splicing of pre‐mRNA to different forms ofmature mRNAbull One snoRNA serves as the template for the synthesis of telomeresbull In vertebrates the snoRNAs are made from introns removed during RNA processing

Non‐coding RNAbullOnly messenger RNA encodes polypeptides Allthe other classes of RNA including types notmentioned here are thus called non‐codingRNAbullMuch remains to be learned about thefunction(s) of some of thembullBut taken together non‐coding RNAs probablyaccount for two‐thirds of the transcription goingon in the nucleus

The RNA polymerasesbullThe RNA polymerases are huge multi‐subunit protein complexesbull Three kinds are found in eukaryotesbullRNA polymerase I (Pol I) It transcribes the rRNA genes for theprecursor of the 28S 18S and 58S molecules (and is the busiestof the RNA polymerases)bull RNA polymerase II (Pol II also known as RNAP II) It transcribesprotein‐encoding genes into mRNA (and also the snRNA genes)bull RNA polymerase III (Pol III) It transcribes the 5S rRNA genes andall the tRNA genes

The steps of RNA processing

bullSynthesis of the cap This is a modified guanine (G) which is attached to the 5prime end ofthe pre‐mRNA as it emerges from RNA polymerase II (RNAP II)bull The cap protects the RNA from being degraded by enzymes that degrade RNA from the 5primeend serves as an assembly point for the proteins needed to recruit the small subunit of theribosome to begin translationbull Step‐by‐step removal of introns present in the pre‐mRNA and splicing of remainingexons This step takes place as the pre‐mRNA continues to emerge from RNAP II

bull Synthesis of the poly(A) tail This is a stretch of adenine (A) nucleotides When aspecial poly(A) attachment site in the pre‐mRNA emerges from RNAP II the transcriptis cut there and the poly(A) tail is attached to the exposed 3prime endbull This completes the mRNA molecule which is now ready for export to the cytosol (Theremainder of the transcript is degraded and the RNA polymerase leaves the DNA) bullThe removal of introns and splicing of exons is done by

The steps of RNA processing

spliceosomesbullThese are a complexes of 5 snRNA molecules and some145 different proteinsbull The introns in most pre‐mRNAs begin with a GU and endwith an AGbullPresumably these short sequences assist in guiding thespliceosome

Components of Translation

1048766Amino acids1048766The tRNA1048766Aminoacyl-tRNA synthetases1048766The mRNA1048766Competent ribosomes1048766Protein factors1048766ATP and GTP

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

Synthesis of the RNA proceeds in the 5prime rarr 3prime directionbull As each nucleoside triphosphate is brought in to add to the 3prime end of the growingstrand the two terminal phosphates are removedbull When transcription is complete the transcript is released from the polymeraseand shortly thereafter the polymerase is released from the DNA

Messenger RNA (mRNA) This will later be translated into a polypeptideribosomal RNA (rRNA) used in the building of rRNA) ribosomes machinery for synthesizing proteinsby translating mRNATransfer RNA (tRNA) RNA molecules that carry amino acids to the growing polypeptideSmall nuclear RNA (snRNA) DNA transcription of the genes for mRNA rRNA and tRNAproduces large precursor molecules (primary transcripts) that must be processed within thenucleus to produce the functional molecules for export to the cytosol

Types of RNA

Small nucleolar RNA (snoRNA) These RNAs within the nucleolus have several functions

MICRORNA (miRNA) These are tiny (~22 nts) RNA molecules that appear to regulate theexpression of messenger RNA (mRNA) moleculesXIST RNA This inactivates one of the two X chromosomes in female vertebrates

Types of RNA

Messenger RNA (mRNA)Messenger RNA comes in a wide range of sizes reflecting the size of thepolypeptide it encodes Most cells produce small amounts of thousandsof different mRNA molecules each to be translated into a peptideneeded by the cellMany mRNAs are common to most cells encoding housekeepingproteins needed by all cells (eg the enzymes of glycolysis) OthermRNAs are specific for only certain types of cells These encode proteinsneeded for the function of that particular cell (eg the mRNA forhemoglobin in the precursors of red blood cells)

Ribosomal RNA (rRNA)bullThere are 4 kinds In eukaryotes these are 18S rRNA One of these moleculesalong with some 30 different protein molecules is used to make the small subunitof the ribosomebull 28S 58S and 5S rRNA One each of these molecules along with some 45different proteins are used to make the large subunit of the ribosomebull The S number given each type of rRNA reflects the rate at which the moleculessediment in the ultracentrifuge The larger the number the larger the molecule(but not proportionally)

bull The 28S 18S and 58S molecules are produced by the processing of a singleprimary transcript from a cluster of identical copies of a single gene The 5Smolecules are produced from a different cluster of identical genes

Transfer RNA (tRNA)bullThere are some 32 different kinds of tRNA in a typical eukaryotic cell Each is theproduct of a separate genebull They are small (~4S) containing 73‐93 nucleotidesbull Many of the bases in the chain pair with each other forming sections of doublehelixbull The unpaired regions form 3 loopsbull Each kind of tRNA carries (at its 3prime end) one of the 20 amino acids (thus mostamino acids have more than one tRNA responsible for them)bull At one loop 3 unpaired bases form an anticodonbull Base pairing between the anticodon and the complementary codon on a mRNAmolecule brings the correct amino acid into the growing polypeptide chain

Small Nuclear RNA (snRNA)

bullApproximately a dozen different genes for snRNAs eachpresent in multiple copies have been identifiedbullThe snRNAs have various roles in the processing of the otherclasses of RNAbull For example several snRNAs are part of the spliceosomesthat participate in converting pre‐mRNA into mRNA byexcising the introns and splicing the exons

Small Nucleolar RNA (snoRNA)bullAs the name suggests these small (60ndash300 nts) RNAs are found in the nucleolus wherethey are responsible for several functions Some participate in making ribosomes by helpingto cut up the large RNA precursor of the 28S 18S and 58S moleculesbull Others chemically modify many of the nucleotides in rRNA tRNA and snRNA moleculeseg by adding methyl groups to ribosebull Some have been implicated in the alternative splicing of pre‐mRNA to different forms ofmature mRNAbull One snoRNA serves as the template for the synthesis of telomeresbull In vertebrates the snoRNAs are made from introns removed during RNA processing

Non‐coding RNAbullOnly messenger RNA encodes polypeptides Allthe other classes of RNA including types notmentioned here are thus called non‐codingRNAbullMuch remains to be learned about thefunction(s) of some of thembullBut taken together non‐coding RNAs probablyaccount for two‐thirds of the transcription goingon in the nucleus

The RNA polymerasesbullThe RNA polymerases are huge multi‐subunit protein complexesbull Three kinds are found in eukaryotesbullRNA polymerase I (Pol I) It transcribes the rRNA genes for theprecursor of the 28S 18S and 58S molecules (and is the busiestof the RNA polymerases)bull RNA polymerase II (Pol II also known as RNAP II) It transcribesprotein‐encoding genes into mRNA (and also the snRNA genes)bull RNA polymerase III (Pol III) It transcribes the 5S rRNA genes andall the tRNA genes

The steps of RNA processing

bullSynthesis of the cap This is a modified guanine (G) which is attached to the 5prime end ofthe pre‐mRNA as it emerges from RNA polymerase II (RNAP II)bull The cap protects the RNA from being degraded by enzymes that degrade RNA from the 5primeend serves as an assembly point for the proteins needed to recruit the small subunit of theribosome to begin translationbull Step‐by‐step removal of introns present in the pre‐mRNA and splicing of remainingexons This step takes place as the pre‐mRNA continues to emerge from RNAP II

bull Synthesis of the poly(A) tail This is a stretch of adenine (A) nucleotides When aspecial poly(A) attachment site in the pre‐mRNA emerges from RNAP II the transcriptis cut there and the poly(A) tail is attached to the exposed 3prime endbull This completes the mRNA molecule which is now ready for export to the cytosol (Theremainder of the transcript is degraded and the RNA polymerase leaves the DNA) bullThe removal of introns and splicing of exons is done by

The steps of RNA processing

spliceosomesbullThese are a complexes of 5 snRNA molecules and some145 different proteinsbull The introns in most pre‐mRNAs begin with a GU and endwith an AGbullPresumably these short sequences assist in guiding thespliceosome

Components of Translation

1048766Amino acids1048766The tRNA1048766Aminoacyl-tRNA synthetases1048766The mRNA1048766Competent ribosomes1048766Protein factors1048766ATP and GTP

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

Messenger RNA (mRNA) This will later be translated into a polypeptideribosomal RNA (rRNA) used in the building of rRNA) ribosomes machinery for synthesizing proteinsby translating mRNATransfer RNA (tRNA) RNA molecules that carry amino acids to the growing polypeptideSmall nuclear RNA (snRNA) DNA transcription of the genes for mRNA rRNA and tRNAproduces large precursor molecules (primary transcripts) that must be processed within thenucleus to produce the functional molecules for export to the cytosol

Types of RNA

Small nucleolar RNA (snoRNA) These RNAs within the nucleolus have several functions

MICRORNA (miRNA) These are tiny (~22 nts) RNA molecules that appear to regulate theexpression of messenger RNA (mRNA) moleculesXIST RNA This inactivates one of the two X chromosomes in female vertebrates

Types of RNA

Messenger RNA (mRNA)Messenger RNA comes in a wide range of sizes reflecting the size of thepolypeptide it encodes Most cells produce small amounts of thousandsof different mRNA molecules each to be translated into a peptideneeded by the cellMany mRNAs are common to most cells encoding housekeepingproteins needed by all cells (eg the enzymes of glycolysis) OthermRNAs are specific for only certain types of cells These encode proteinsneeded for the function of that particular cell (eg the mRNA forhemoglobin in the precursors of red blood cells)

Ribosomal RNA (rRNA)bullThere are 4 kinds In eukaryotes these are 18S rRNA One of these moleculesalong with some 30 different protein molecules is used to make the small subunitof the ribosomebull 28S 58S and 5S rRNA One each of these molecules along with some 45different proteins are used to make the large subunit of the ribosomebull The S number given each type of rRNA reflects the rate at which the moleculessediment in the ultracentrifuge The larger the number the larger the molecule(but not proportionally)

bull The 28S 18S and 58S molecules are produced by the processing of a singleprimary transcript from a cluster of identical copies of a single gene The 5Smolecules are produced from a different cluster of identical genes

Transfer RNA (tRNA)bullThere are some 32 different kinds of tRNA in a typical eukaryotic cell Each is theproduct of a separate genebull They are small (~4S) containing 73‐93 nucleotidesbull Many of the bases in the chain pair with each other forming sections of doublehelixbull The unpaired regions form 3 loopsbull Each kind of tRNA carries (at its 3prime end) one of the 20 amino acids (thus mostamino acids have more than one tRNA responsible for them)bull At one loop 3 unpaired bases form an anticodonbull Base pairing between the anticodon and the complementary codon on a mRNAmolecule brings the correct amino acid into the growing polypeptide chain

Small Nuclear RNA (snRNA)

bullApproximately a dozen different genes for snRNAs eachpresent in multiple copies have been identifiedbullThe snRNAs have various roles in the processing of the otherclasses of RNAbull For example several snRNAs are part of the spliceosomesthat participate in converting pre‐mRNA into mRNA byexcising the introns and splicing the exons

Small Nucleolar RNA (snoRNA)bullAs the name suggests these small (60ndash300 nts) RNAs are found in the nucleolus wherethey are responsible for several functions Some participate in making ribosomes by helpingto cut up the large RNA precursor of the 28S 18S and 58S moleculesbull Others chemically modify many of the nucleotides in rRNA tRNA and snRNA moleculeseg by adding methyl groups to ribosebull Some have been implicated in the alternative splicing of pre‐mRNA to different forms ofmature mRNAbull One snoRNA serves as the template for the synthesis of telomeresbull In vertebrates the snoRNAs are made from introns removed during RNA processing

Non‐coding RNAbullOnly messenger RNA encodes polypeptides Allthe other classes of RNA including types notmentioned here are thus called non‐codingRNAbullMuch remains to be learned about thefunction(s) of some of thembullBut taken together non‐coding RNAs probablyaccount for two‐thirds of the transcription goingon in the nucleus

The RNA polymerasesbullThe RNA polymerases are huge multi‐subunit protein complexesbull Three kinds are found in eukaryotesbullRNA polymerase I (Pol I) It transcribes the rRNA genes for theprecursor of the 28S 18S and 58S molecules (and is the busiestof the RNA polymerases)bull RNA polymerase II (Pol II also known as RNAP II) It transcribesprotein‐encoding genes into mRNA (and also the snRNA genes)bull RNA polymerase III (Pol III) It transcribes the 5S rRNA genes andall the tRNA genes

The steps of RNA processing

bullSynthesis of the cap This is a modified guanine (G) which is attached to the 5prime end ofthe pre‐mRNA as it emerges from RNA polymerase II (RNAP II)bull The cap protects the RNA from being degraded by enzymes that degrade RNA from the 5primeend serves as an assembly point for the proteins needed to recruit the small subunit of theribosome to begin translationbull Step‐by‐step removal of introns present in the pre‐mRNA and splicing of remainingexons This step takes place as the pre‐mRNA continues to emerge from RNAP II

bull Synthesis of the poly(A) tail This is a stretch of adenine (A) nucleotides When aspecial poly(A) attachment site in the pre‐mRNA emerges from RNAP II the transcriptis cut there and the poly(A) tail is attached to the exposed 3prime endbull This completes the mRNA molecule which is now ready for export to the cytosol (Theremainder of the transcript is degraded and the RNA polymerase leaves the DNA) bullThe removal of introns and splicing of exons is done by

The steps of RNA processing

spliceosomesbullThese are a complexes of 5 snRNA molecules and some145 different proteinsbull The introns in most pre‐mRNAs begin with a GU and endwith an AGbullPresumably these short sequences assist in guiding thespliceosome

Components of Translation

1048766Amino acids1048766The tRNA1048766Aminoacyl-tRNA synthetases1048766The mRNA1048766Competent ribosomes1048766Protein factors1048766ATP and GTP

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

Small nucleolar RNA (snoRNA) These RNAs within the nucleolus have several functions

MICRORNA (miRNA) These are tiny (~22 nts) RNA molecules that appear to regulate theexpression of messenger RNA (mRNA) moleculesXIST RNA This inactivates one of the two X chromosomes in female vertebrates

Types of RNA

Messenger RNA (mRNA)Messenger RNA comes in a wide range of sizes reflecting the size of thepolypeptide it encodes Most cells produce small amounts of thousandsof different mRNA molecules each to be translated into a peptideneeded by the cellMany mRNAs are common to most cells encoding housekeepingproteins needed by all cells (eg the enzymes of glycolysis) OthermRNAs are specific for only certain types of cells These encode proteinsneeded for the function of that particular cell (eg the mRNA forhemoglobin in the precursors of red blood cells)

Ribosomal RNA (rRNA)bullThere are 4 kinds In eukaryotes these are 18S rRNA One of these moleculesalong with some 30 different protein molecules is used to make the small subunitof the ribosomebull 28S 58S and 5S rRNA One each of these molecules along with some 45different proteins are used to make the large subunit of the ribosomebull The S number given each type of rRNA reflects the rate at which the moleculessediment in the ultracentrifuge The larger the number the larger the molecule(but not proportionally)

bull The 28S 18S and 58S molecules are produced by the processing of a singleprimary transcript from a cluster of identical copies of a single gene The 5Smolecules are produced from a different cluster of identical genes

Transfer RNA (tRNA)bullThere are some 32 different kinds of tRNA in a typical eukaryotic cell Each is theproduct of a separate genebull They are small (~4S) containing 73‐93 nucleotidesbull Many of the bases in the chain pair with each other forming sections of doublehelixbull The unpaired regions form 3 loopsbull Each kind of tRNA carries (at its 3prime end) one of the 20 amino acids (thus mostamino acids have more than one tRNA responsible for them)bull At one loop 3 unpaired bases form an anticodonbull Base pairing between the anticodon and the complementary codon on a mRNAmolecule brings the correct amino acid into the growing polypeptide chain

Small Nuclear RNA (snRNA)

bullApproximately a dozen different genes for snRNAs eachpresent in multiple copies have been identifiedbullThe snRNAs have various roles in the processing of the otherclasses of RNAbull For example several snRNAs are part of the spliceosomesthat participate in converting pre‐mRNA into mRNA byexcising the introns and splicing the exons

Small Nucleolar RNA (snoRNA)bullAs the name suggests these small (60ndash300 nts) RNAs are found in the nucleolus wherethey are responsible for several functions Some participate in making ribosomes by helpingto cut up the large RNA precursor of the 28S 18S and 58S moleculesbull Others chemically modify many of the nucleotides in rRNA tRNA and snRNA moleculeseg by adding methyl groups to ribosebull Some have been implicated in the alternative splicing of pre‐mRNA to different forms ofmature mRNAbull One snoRNA serves as the template for the synthesis of telomeresbull In vertebrates the snoRNAs are made from introns removed during RNA processing

Non‐coding RNAbullOnly messenger RNA encodes polypeptides Allthe other classes of RNA including types notmentioned here are thus called non‐codingRNAbullMuch remains to be learned about thefunction(s) of some of thembullBut taken together non‐coding RNAs probablyaccount for two‐thirds of the transcription goingon in the nucleus

The RNA polymerasesbullThe RNA polymerases are huge multi‐subunit protein complexesbull Three kinds are found in eukaryotesbullRNA polymerase I (Pol I) It transcribes the rRNA genes for theprecursor of the 28S 18S and 58S molecules (and is the busiestof the RNA polymerases)bull RNA polymerase II (Pol II also known as RNAP II) It transcribesprotein‐encoding genes into mRNA (and also the snRNA genes)bull RNA polymerase III (Pol III) It transcribes the 5S rRNA genes andall the tRNA genes

The steps of RNA processing

bullSynthesis of the cap This is a modified guanine (G) which is attached to the 5prime end ofthe pre‐mRNA as it emerges from RNA polymerase II (RNAP II)bull The cap protects the RNA from being degraded by enzymes that degrade RNA from the 5primeend serves as an assembly point for the proteins needed to recruit the small subunit of theribosome to begin translationbull Step‐by‐step removal of introns present in the pre‐mRNA and splicing of remainingexons This step takes place as the pre‐mRNA continues to emerge from RNAP II

bull Synthesis of the poly(A) tail This is a stretch of adenine (A) nucleotides When aspecial poly(A) attachment site in the pre‐mRNA emerges from RNAP II the transcriptis cut there and the poly(A) tail is attached to the exposed 3prime endbull This completes the mRNA molecule which is now ready for export to the cytosol (Theremainder of the transcript is degraded and the RNA polymerase leaves the DNA) bullThe removal of introns and splicing of exons is done by

The steps of RNA processing

spliceosomesbullThese are a complexes of 5 snRNA molecules and some145 different proteinsbull The introns in most pre‐mRNAs begin with a GU and endwith an AGbullPresumably these short sequences assist in guiding thespliceosome

Components of Translation

1048766Amino acids1048766The tRNA1048766Aminoacyl-tRNA synthetases1048766The mRNA1048766Competent ribosomes1048766Protein factors1048766ATP and GTP

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

Messenger RNA (mRNA)Messenger RNA comes in a wide range of sizes reflecting the size of thepolypeptide it encodes Most cells produce small amounts of thousandsof different mRNA molecules each to be translated into a peptideneeded by the cellMany mRNAs are common to most cells encoding housekeepingproteins needed by all cells (eg the enzymes of glycolysis) OthermRNAs are specific for only certain types of cells These encode proteinsneeded for the function of that particular cell (eg the mRNA forhemoglobin in the precursors of red blood cells)

Ribosomal RNA (rRNA)bullThere are 4 kinds In eukaryotes these are 18S rRNA One of these moleculesalong with some 30 different protein molecules is used to make the small subunitof the ribosomebull 28S 58S and 5S rRNA One each of these molecules along with some 45different proteins are used to make the large subunit of the ribosomebull The S number given each type of rRNA reflects the rate at which the moleculessediment in the ultracentrifuge The larger the number the larger the molecule(but not proportionally)

bull The 28S 18S and 58S molecules are produced by the processing of a singleprimary transcript from a cluster of identical copies of a single gene The 5Smolecules are produced from a different cluster of identical genes

Transfer RNA (tRNA)bullThere are some 32 different kinds of tRNA in a typical eukaryotic cell Each is theproduct of a separate genebull They are small (~4S) containing 73‐93 nucleotidesbull Many of the bases in the chain pair with each other forming sections of doublehelixbull The unpaired regions form 3 loopsbull Each kind of tRNA carries (at its 3prime end) one of the 20 amino acids (thus mostamino acids have more than one tRNA responsible for them)bull At one loop 3 unpaired bases form an anticodonbull Base pairing between the anticodon and the complementary codon on a mRNAmolecule brings the correct amino acid into the growing polypeptide chain

Small Nuclear RNA (snRNA)

bullApproximately a dozen different genes for snRNAs eachpresent in multiple copies have been identifiedbullThe snRNAs have various roles in the processing of the otherclasses of RNAbull For example several snRNAs are part of the spliceosomesthat participate in converting pre‐mRNA into mRNA byexcising the introns and splicing the exons

Small Nucleolar RNA (snoRNA)bullAs the name suggests these small (60ndash300 nts) RNAs are found in the nucleolus wherethey are responsible for several functions Some participate in making ribosomes by helpingto cut up the large RNA precursor of the 28S 18S and 58S moleculesbull Others chemically modify many of the nucleotides in rRNA tRNA and snRNA moleculeseg by adding methyl groups to ribosebull Some have been implicated in the alternative splicing of pre‐mRNA to different forms ofmature mRNAbull One snoRNA serves as the template for the synthesis of telomeresbull In vertebrates the snoRNAs are made from introns removed during RNA processing

Non‐coding RNAbullOnly messenger RNA encodes polypeptides Allthe other classes of RNA including types notmentioned here are thus called non‐codingRNAbullMuch remains to be learned about thefunction(s) of some of thembullBut taken together non‐coding RNAs probablyaccount for two‐thirds of the transcription goingon in the nucleus

The RNA polymerasesbullThe RNA polymerases are huge multi‐subunit protein complexesbull Three kinds are found in eukaryotesbullRNA polymerase I (Pol I) It transcribes the rRNA genes for theprecursor of the 28S 18S and 58S molecules (and is the busiestof the RNA polymerases)bull RNA polymerase II (Pol II also known as RNAP II) It transcribesprotein‐encoding genes into mRNA (and also the snRNA genes)bull RNA polymerase III (Pol III) It transcribes the 5S rRNA genes andall the tRNA genes

The steps of RNA processing

bullSynthesis of the cap This is a modified guanine (G) which is attached to the 5prime end ofthe pre‐mRNA as it emerges from RNA polymerase II (RNAP II)bull The cap protects the RNA from being degraded by enzymes that degrade RNA from the 5primeend serves as an assembly point for the proteins needed to recruit the small subunit of theribosome to begin translationbull Step‐by‐step removal of introns present in the pre‐mRNA and splicing of remainingexons This step takes place as the pre‐mRNA continues to emerge from RNAP II

bull Synthesis of the poly(A) tail This is a stretch of adenine (A) nucleotides When aspecial poly(A) attachment site in the pre‐mRNA emerges from RNAP II the transcriptis cut there and the poly(A) tail is attached to the exposed 3prime endbull This completes the mRNA molecule which is now ready for export to the cytosol (Theremainder of the transcript is degraded and the RNA polymerase leaves the DNA) bullThe removal of introns and splicing of exons is done by

The steps of RNA processing

spliceosomesbullThese are a complexes of 5 snRNA molecules and some145 different proteinsbull The introns in most pre‐mRNAs begin with a GU and endwith an AGbullPresumably these short sequences assist in guiding thespliceosome

Components of Translation

1048766Amino acids1048766The tRNA1048766Aminoacyl-tRNA synthetases1048766The mRNA1048766Competent ribosomes1048766Protein factors1048766ATP and GTP

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

Ribosomal RNA (rRNA)bullThere are 4 kinds In eukaryotes these are 18S rRNA One of these moleculesalong with some 30 different protein molecules is used to make the small subunitof the ribosomebull 28S 58S and 5S rRNA One each of these molecules along with some 45different proteins are used to make the large subunit of the ribosomebull The S number given each type of rRNA reflects the rate at which the moleculessediment in the ultracentrifuge The larger the number the larger the molecule(but not proportionally)

bull The 28S 18S and 58S molecules are produced by the processing of a singleprimary transcript from a cluster of identical copies of a single gene The 5Smolecules are produced from a different cluster of identical genes

Transfer RNA (tRNA)bullThere are some 32 different kinds of tRNA in a typical eukaryotic cell Each is theproduct of a separate genebull They are small (~4S) containing 73‐93 nucleotidesbull Many of the bases in the chain pair with each other forming sections of doublehelixbull The unpaired regions form 3 loopsbull Each kind of tRNA carries (at its 3prime end) one of the 20 amino acids (thus mostamino acids have more than one tRNA responsible for them)bull At one loop 3 unpaired bases form an anticodonbull Base pairing between the anticodon and the complementary codon on a mRNAmolecule brings the correct amino acid into the growing polypeptide chain

Small Nuclear RNA (snRNA)

bullApproximately a dozen different genes for snRNAs eachpresent in multiple copies have been identifiedbullThe snRNAs have various roles in the processing of the otherclasses of RNAbull For example several snRNAs are part of the spliceosomesthat participate in converting pre‐mRNA into mRNA byexcising the introns and splicing the exons

Small Nucleolar RNA (snoRNA)bullAs the name suggests these small (60ndash300 nts) RNAs are found in the nucleolus wherethey are responsible for several functions Some participate in making ribosomes by helpingto cut up the large RNA precursor of the 28S 18S and 58S moleculesbull Others chemically modify many of the nucleotides in rRNA tRNA and snRNA moleculeseg by adding methyl groups to ribosebull Some have been implicated in the alternative splicing of pre‐mRNA to different forms ofmature mRNAbull One snoRNA serves as the template for the synthesis of telomeresbull In vertebrates the snoRNAs are made from introns removed during RNA processing

Non‐coding RNAbullOnly messenger RNA encodes polypeptides Allthe other classes of RNA including types notmentioned here are thus called non‐codingRNAbullMuch remains to be learned about thefunction(s) of some of thembullBut taken together non‐coding RNAs probablyaccount for two‐thirds of the transcription goingon in the nucleus

The RNA polymerasesbullThe RNA polymerases are huge multi‐subunit protein complexesbull Three kinds are found in eukaryotesbullRNA polymerase I (Pol I) It transcribes the rRNA genes for theprecursor of the 28S 18S and 58S molecules (and is the busiestof the RNA polymerases)bull RNA polymerase II (Pol II also known as RNAP II) It transcribesprotein‐encoding genes into mRNA (and also the snRNA genes)bull RNA polymerase III (Pol III) It transcribes the 5S rRNA genes andall the tRNA genes

The steps of RNA processing

bullSynthesis of the cap This is a modified guanine (G) which is attached to the 5prime end ofthe pre‐mRNA as it emerges from RNA polymerase II (RNAP II)bull The cap protects the RNA from being degraded by enzymes that degrade RNA from the 5primeend serves as an assembly point for the proteins needed to recruit the small subunit of theribosome to begin translationbull Step‐by‐step removal of introns present in the pre‐mRNA and splicing of remainingexons This step takes place as the pre‐mRNA continues to emerge from RNAP II

bull Synthesis of the poly(A) tail This is a stretch of adenine (A) nucleotides When aspecial poly(A) attachment site in the pre‐mRNA emerges from RNAP II the transcriptis cut there and the poly(A) tail is attached to the exposed 3prime endbull This completes the mRNA molecule which is now ready for export to the cytosol (Theremainder of the transcript is degraded and the RNA polymerase leaves the DNA) bullThe removal of introns and splicing of exons is done by

The steps of RNA processing

spliceosomesbullThese are a complexes of 5 snRNA molecules and some145 different proteinsbull The introns in most pre‐mRNAs begin with a GU and endwith an AGbullPresumably these short sequences assist in guiding thespliceosome

Components of Translation

1048766Amino acids1048766The tRNA1048766Aminoacyl-tRNA synthetases1048766The mRNA1048766Competent ribosomes1048766Protein factors1048766ATP and GTP

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

bull The 28S 18S and 58S molecules are produced by the processing of a singleprimary transcript from a cluster of identical copies of a single gene The 5Smolecules are produced from a different cluster of identical genes

Transfer RNA (tRNA)bullThere are some 32 different kinds of tRNA in a typical eukaryotic cell Each is theproduct of a separate genebull They are small (~4S) containing 73‐93 nucleotidesbull Many of the bases in the chain pair with each other forming sections of doublehelixbull The unpaired regions form 3 loopsbull Each kind of tRNA carries (at its 3prime end) one of the 20 amino acids (thus mostamino acids have more than one tRNA responsible for them)bull At one loop 3 unpaired bases form an anticodonbull Base pairing between the anticodon and the complementary codon on a mRNAmolecule brings the correct amino acid into the growing polypeptide chain

Small Nuclear RNA (snRNA)

bullApproximately a dozen different genes for snRNAs eachpresent in multiple copies have been identifiedbullThe snRNAs have various roles in the processing of the otherclasses of RNAbull For example several snRNAs are part of the spliceosomesthat participate in converting pre‐mRNA into mRNA byexcising the introns and splicing the exons

Small Nucleolar RNA (snoRNA)bullAs the name suggests these small (60ndash300 nts) RNAs are found in the nucleolus wherethey are responsible for several functions Some participate in making ribosomes by helpingto cut up the large RNA precursor of the 28S 18S and 58S moleculesbull Others chemically modify many of the nucleotides in rRNA tRNA and snRNA moleculeseg by adding methyl groups to ribosebull Some have been implicated in the alternative splicing of pre‐mRNA to different forms ofmature mRNAbull One snoRNA serves as the template for the synthesis of telomeresbull In vertebrates the snoRNAs are made from introns removed during RNA processing

Non‐coding RNAbullOnly messenger RNA encodes polypeptides Allthe other classes of RNA including types notmentioned here are thus called non‐codingRNAbullMuch remains to be learned about thefunction(s) of some of thembullBut taken together non‐coding RNAs probablyaccount for two‐thirds of the transcription goingon in the nucleus

The RNA polymerasesbullThe RNA polymerases are huge multi‐subunit protein complexesbull Three kinds are found in eukaryotesbullRNA polymerase I (Pol I) It transcribes the rRNA genes for theprecursor of the 28S 18S and 58S molecules (and is the busiestof the RNA polymerases)bull RNA polymerase II (Pol II also known as RNAP II) It transcribesprotein‐encoding genes into mRNA (and also the snRNA genes)bull RNA polymerase III (Pol III) It transcribes the 5S rRNA genes andall the tRNA genes

The steps of RNA processing

bullSynthesis of the cap This is a modified guanine (G) which is attached to the 5prime end ofthe pre‐mRNA as it emerges from RNA polymerase II (RNAP II)bull The cap protects the RNA from being degraded by enzymes that degrade RNA from the 5primeend serves as an assembly point for the proteins needed to recruit the small subunit of theribosome to begin translationbull Step‐by‐step removal of introns present in the pre‐mRNA and splicing of remainingexons This step takes place as the pre‐mRNA continues to emerge from RNAP II

bull Synthesis of the poly(A) tail This is a stretch of adenine (A) nucleotides When aspecial poly(A) attachment site in the pre‐mRNA emerges from RNAP II the transcriptis cut there and the poly(A) tail is attached to the exposed 3prime endbull This completes the mRNA molecule which is now ready for export to the cytosol (Theremainder of the transcript is degraded and the RNA polymerase leaves the DNA) bullThe removal of introns and splicing of exons is done by

The steps of RNA processing

spliceosomesbullThese are a complexes of 5 snRNA molecules and some145 different proteinsbull The introns in most pre‐mRNAs begin with a GU and endwith an AGbullPresumably these short sequences assist in guiding thespliceosome

Components of Translation

1048766Amino acids1048766The tRNA1048766Aminoacyl-tRNA synthetases1048766The mRNA1048766Competent ribosomes1048766Protein factors1048766ATP and GTP

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

Transfer RNA (tRNA)bullThere are some 32 different kinds of tRNA in a typical eukaryotic cell Each is theproduct of a separate genebull They are small (~4S) containing 73‐93 nucleotidesbull Many of the bases in the chain pair with each other forming sections of doublehelixbull The unpaired regions form 3 loopsbull Each kind of tRNA carries (at its 3prime end) one of the 20 amino acids (thus mostamino acids have more than one tRNA responsible for them)bull At one loop 3 unpaired bases form an anticodonbull Base pairing between the anticodon and the complementary codon on a mRNAmolecule brings the correct amino acid into the growing polypeptide chain

Small Nuclear RNA (snRNA)

bullApproximately a dozen different genes for snRNAs eachpresent in multiple copies have been identifiedbullThe snRNAs have various roles in the processing of the otherclasses of RNAbull For example several snRNAs are part of the spliceosomesthat participate in converting pre‐mRNA into mRNA byexcising the introns and splicing the exons

Small Nucleolar RNA (snoRNA)bullAs the name suggests these small (60ndash300 nts) RNAs are found in the nucleolus wherethey are responsible for several functions Some participate in making ribosomes by helpingto cut up the large RNA precursor of the 28S 18S and 58S moleculesbull Others chemically modify many of the nucleotides in rRNA tRNA and snRNA moleculeseg by adding methyl groups to ribosebull Some have been implicated in the alternative splicing of pre‐mRNA to different forms ofmature mRNAbull One snoRNA serves as the template for the synthesis of telomeresbull In vertebrates the snoRNAs are made from introns removed during RNA processing

Non‐coding RNAbullOnly messenger RNA encodes polypeptides Allthe other classes of RNA including types notmentioned here are thus called non‐codingRNAbullMuch remains to be learned about thefunction(s) of some of thembullBut taken together non‐coding RNAs probablyaccount for two‐thirds of the transcription goingon in the nucleus

The RNA polymerasesbullThe RNA polymerases are huge multi‐subunit protein complexesbull Three kinds are found in eukaryotesbullRNA polymerase I (Pol I) It transcribes the rRNA genes for theprecursor of the 28S 18S and 58S molecules (and is the busiestof the RNA polymerases)bull RNA polymerase II (Pol II also known as RNAP II) It transcribesprotein‐encoding genes into mRNA (and also the snRNA genes)bull RNA polymerase III (Pol III) It transcribes the 5S rRNA genes andall the tRNA genes

The steps of RNA processing

bullSynthesis of the cap This is a modified guanine (G) which is attached to the 5prime end ofthe pre‐mRNA as it emerges from RNA polymerase II (RNAP II)bull The cap protects the RNA from being degraded by enzymes that degrade RNA from the 5primeend serves as an assembly point for the proteins needed to recruit the small subunit of theribosome to begin translationbull Step‐by‐step removal of introns present in the pre‐mRNA and splicing of remainingexons This step takes place as the pre‐mRNA continues to emerge from RNAP II

bull Synthesis of the poly(A) tail This is a stretch of adenine (A) nucleotides When aspecial poly(A) attachment site in the pre‐mRNA emerges from RNAP II the transcriptis cut there and the poly(A) tail is attached to the exposed 3prime endbull This completes the mRNA molecule which is now ready for export to the cytosol (Theremainder of the transcript is degraded and the RNA polymerase leaves the DNA) bullThe removal of introns and splicing of exons is done by

The steps of RNA processing

spliceosomesbullThese are a complexes of 5 snRNA molecules and some145 different proteinsbull The introns in most pre‐mRNAs begin with a GU and endwith an AGbullPresumably these short sequences assist in guiding thespliceosome

Components of Translation

1048766Amino acids1048766The tRNA1048766Aminoacyl-tRNA synthetases1048766The mRNA1048766Competent ribosomes1048766Protein factors1048766ATP and GTP

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

Small Nuclear RNA (snRNA)

bullApproximately a dozen different genes for snRNAs eachpresent in multiple copies have been identifiedbullThe snRNAs have various roles in the processing of the otherclasses of RNAbull For example several snRNAs are part of the spliceosomesthat participate in converting pre‐mRNA into mRNA byexcising the introns and splicing the exons

Small Nucleolar RNA (snoRNA)bullAs the name suggests these small (60ndash300 nts) RNAs are found in the nucleolus wherethey are responsible for several functions Some participate in making ribosomes by helpingto cut up the large RNA precursor of the 28S 18S and 58S moleculesbull Others chemically modify many of the nucleotides in rRNA tRNA and snRNA moleculeseg by adding methyl groups to ribosebull Some have been implicated in the alternative splicing of pre‐mRNA to different forms ofmature mRNAbull One snoRNA serves as the template for the synthesis of telomeresbull In vertebrates the snoRNAs are made from introns removed during RNA processing

Non‐coding RNAbullOnly messenger RNA encodes polypeptides Allthe other classes of RNA including types notmentioned here are thus called non‐codingRNAbullMuch remains to be learned about thefunction(s) of some of thembullBut taken together non‐coding RNAs probablyaccount for two‐thirds of the transcription goingon in the nucleus

The RNA polymerasesbullThe RNA polymerases are huge multi‐subunit protein complexesbull Three kinds are found in eukaryotesbullRNA polymerase I (Pol I) It transcribes the rRNA genes for theprecursor of the 28S 18S and 58S molecules (and is the busiestof the RNA polymerases)bull RNA polymerase II (Pol II also known as RNAP II) It transcribesprotein‐encoding genes into mRNA (and also the snRNA genes)bull RNA polymerase III (Pol III) It transcribes the 5S rRNA genes andall the tRNA genes

The steps of RNA processing

bullSynthesis of the cap This is a modified guanine (G) which is attached to the 5prime end ofthe pre‐mRNA as it emerges from RNA polymerase II (RNAP II)bull The cap protects the RNA from being degraded by enzymes that degrade RNA from the 5primeend serves as an assembly point for the proteins needed to recruit the small subunit of theribosome to begin translationbull Step‐by‐step removal of introns present in the pre‐mRNA and splicing of remainingexons This step takes place as the pre‐mRNA continues to emerge from RNAP II

bull Synthesis of the poly(A) tail This is a stretch of adenine (A) nucleotides When aspecial poly(A) attachment site in the pre‐mRNA emerges from RNAP II the transcriptis cut there and the poly(A) tail is attached to the exposed 3prime endbull This completes the mRNA molecule which is now ready for export to the cytosol (Theremainder of the transcript is degraded and the RNA polymerase leaves the DNA) bullThe removal of introns and splicing of exons is done by

The steps of RNA processing

spliceosomesbullThese are a complexes of 5 snRNA molecules and some145 different proteinsbull The introns in most pre‐mRNAs begin with a GU and endwith an AGbullPresumably these short sequences assist in guiding thespliceosome

Components of Translation

1048766Amino acids1048766The tRNA1048766Aminoacyl-tRNA synthetases1048766The mRNA1048766Competent ribosomes1048766Protein factors1048766ATP and GTP

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

Small Nucleolar RNA (snoRNA)bullAs the name suggests these small (60ndash300 nts) RNAs are found in the nucleolus wherethey are responsible for several functions Some participate in making ribosomes by helpingto cut up the large RNA precursor of the 28S 18S and 58S moleculesbull Others chemically modify many of the nucleotides in rRNA tRNA and snRNA moleculeseg by adding methyl groups to ribosebull Some have been implicated in the alternative splicing of pre‐mRNA to different forms ofmature mRNAbull One snoRNA serves as the template for the synthesis of telomeresbull In vertebrates the snoRNAs are made from introns removed during RNA processing

Non‐coding RNAbullOnly messenger RNA encodes polypeptides Allthe other classes of RNA including types notmentioned here are thus called non‐codingRNAbullMuch remains to be learned about thefunction(s) of some of thembullBut taken together non‐coding RNAs probablyaccount for two‐thirds of the transcription goingon in the nucleus

The RNA polymerasesbullThe RNA polymerases are huge multi‐subunit protein complexesbull Three kinds are found in eukaryotesbullRNA polymerase I (Pol I) It transcribes the rRNA genes for theprecursor of the 28S 18S and 58S molecules (and is the busiestof the RNA polymerases)bull RNA polymerase II (Pol II also known as RNAP II) It transcribesprotein‐encoding genes into mRNA (and also the snRNA genes)bull RNA polymerase III (Pol III) It transcribes the 5S rRNA genes andall the tRNA genes

The steps of RNA processing

bullSynthesis of the cap This is a modified guanine (G) which is attached to the 5prime end ofthe pre‐mRNA as it emerges from RNA polymerase II (RNAP II)bull The cap protects the RNA from being degraded by enzymes that degrade RNA from the 5primeend serves as an assembly point for the proteins needed to recruit the small subunit of theribosome to begin translationbull Step‐by‐step removal of introns present in the pre‐mRNA and splicing of remainingexons This step takes place as the pre‐mRNA continues to emerge from RNAP II

bull Synthesis of the poly(A) tail This is a stretch of adenine (A) nucleotides When aspecial poly(A) attachment site in the pre‐mRNA emerges from RNAP II the transcriptis cut there and the poly(A) tail is attached to the exposed 3prime endbull This completes the mRNA molecule which is now ready for export to the cytosol (Theremainder of the transcript is degraded and the RNA polymerase leaves the DNA) bullThe removal of introns and splicing of exons is done by

The steps of RNA processing

spliceosomesbullThese are a complexes of 5 snRNA molecules and some145 different proteinsbull The introns in most pre‐mRNAs begin with a GU and endwith an AGbullPresumably these short sequences assist in guiding thespliceosome

Components of Translation

1048766Amino acids1048766The tRNA1048766Aminoacyl-tRNA synthetases1048766The mRNA1048766Competent ribosomes1048766Protein factors1048766ATP and GTP

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

Non‐coding RNAbullOnly messenger RNA encodes polypeptides Allthe other classes of RNA including types notmentioned here are thus called non‐codingRNAbullMuch remains to be learned about thefunction(s) of some of thembullBut taken together non‐coding RNAs probablyaccount for two‐thirds of the transcription goingon in the nucleus

The RNA polymerasesbullThe RNA polymerases are huge multi‐subunit protein complexesbull Three kinds are found in eukaryotesbullRNA polymerase I (Pol I) It transcribes the rRNA genes for theprecursor of the 28S 18S and 58S molecules (and is the busiestof the RNA polymerases)bull RNA polymerase II (Pol II also known as RNAP II) It transcribesprotein‐encoding genes into mRNA (and also the snRNA genes)bull RNA polymerase III (Pol III) It transcribes the 5S rRNA genes andall the tRNA genes

The steps of RNA processing

bullSynthesis of the cap This is a modified guanine (G) which is attached to the 5prime end ofthe pre‐mRNA as it emerges from RNA polymerase II (RNAP II)bull The cap protects the RNA from being degraded by enzymes that degrade RNA from the 5primeend serves as an assembly point for the proteins needed to recruit the small subunit of theribosome to begin translationbull Step‐by‐step removal of introns present in the pre‐mRNA and splicing of remainingexons This step takes place as the pre‐mRNA continues to emerge from RNAP II

bull Synthesis of the poly(A) tail This is a stretch of adenine (A) nucleotides When aspecial poly(A) attachment site in the pre‐mRNA emerges from RNAP II the transcriptis cut there and the poly(A) tail is attached to the exposed 3prime endbull This completes the mRNA molecule which is now ready for export to the cytosol (Theremainder of the transcript is degraded and the RNA polymerase leaves the DNA) bullThe removal of introns and splicing of exons is done by

The steps of RNA processing

spliceosomesbullThese are a complexes of 5 snRNA molecules and some145 different proteinsbull The introns in most pre‐mRNAs begin with a GU and endwith an AGbullPresumably these short sequences assist in guiding thespliceosome

Components of Translation

1048766Amino acids1048766The tRNA1048766Aminoacyl-tRNA synthetases1048766The mRNA1048766Competent ribosomes1048766Protein factors1048766ATP and GTP

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

The RNA polymerasesbullThe RNA polymerases are huge multi‐subunit protein complexesbull Three kinds are found in eukaryotesbullRNA polymerase I (Pol I) It transcribes the rRNA genes for theprecursor of the 28S 18S and 58S molecules (and is the busiestof the RNA polymerases)bull RNA polymerase II (Pol II also known as RNAP II) It transcribesprotein‐encoding genes into mRNA (and also the snRNA genes)bull RNA polymerase III (Pol III) It transcribes the 5S rRNA genes andall the tRNA genes

The steps of RNA processing

bullSynthesis of the cap This is a modified guanine (G) which is attached to the 5prime end ofthe pre‐mRNA as it emerges from RNA polymerase II (RNAP II)bull The cap protects the RNA from being degraded by enzymes that degrade RNA from the 5primeend serves as an assembly point for the proteins needed to recruit the small subunit of theribosome to begin translationbull Step‐by‐step removal of introns present in the pre‐mRNA and splicing of remainingexons This step takes place as the pre‐mRNA continues to emerge from RNAP II

bull Synthesis of the poly(A) tail This is a stretch of adenine (A) nucleotides When aspecial poly(A) attachment site in the pre‐mRNA emerges from RNAP II the transcriptis cut there and the poly(A) tail is attached to the exposed 3prime endbull This completes the mRNA molecule which is now ready for export to the cytosol (Theremainder of the transcript is degraded and the RNA polymerase leaves the DNA) bullThe removal of introns and splicing of exons is done by

The steps of RNA processing

spliceosomesbullThese are a complexes of 5 snRNA molecules and some145 different proteinsbull The introns in most pre‐mRNAs begin with a GU and endwith an AGbullPresumably these short sequences assist in guiding thespliceosome

Components of Translation

1048766Amino acids1048766The tRNA1048766Aminoacyl-tRNA synthetases1048766The mRNA1048766Competent ribosomes1048766Protein factors1048766ATP and GTP

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

The steps of RNA processing

bullSynthesis of the cap This is a modified guanine (G) which is attached to the 5prime end ofthe pre‐mRNA as it emerges from RNA polymerase II (RNAP II)bull The cap protects the RNA from being degraded by enzymes that degrade RNA from the 5primeend serves as an assembly point for the proteins needed to recruit the small subunit of theribosome to begin translationbull Step‐by‐step removal of introns present in the pre‐mRNA and splicing of remainingexons This step takes place as the pre‐mRNA continues to emerge from RNAP II

bull Synthesis of the poly(A) tail This is a stretch of adenine (A) nucleotides When aspecial poly(A) attachment site in the pre‐mRNA emerges from RNAP II the transcriptis cut there and the poly(A) tail is attached to the exposed 3prime endbull This completes the mRNA molecule which is now ready for export to the cytosol (Theremainder of the transcript is degraded and the RNA polymerase leaves the DNA) bullThe removal of introns and splicing of exons is done by

The steps of RNA processing

spliceosomesbullThese are a complexes of 5 snRNA molecules and some145 different proteinsbull The introns in most pre‐mRNAs begin with a GU and endwith an AGbullPresumably these short sequences assist in guiding thespliceosome

Components of Translation

1048766Amino acids1048766The tRNA1048766Aminoacyl-tRNA synthetases1048766The mRNA1048766Competent ribosomes1048766Protein factors1048766ATP and GTP

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

bull Synthesis of the poly(A) tail This is a stretch of adenine (A) nucleotides When aspecial poly(A) attachment site in the pre‐mRNA emerges from RNAP II the transcriptis cut there and the poly(A) tail is attached to the exposed 3prime endbull This completes the mRNA molecule which is now ready for export to the cytosol (Theremainder of the transcript is degraded and the RNA polymerase leaves the DNA) bullThe removal of introns and splicing of exons is done by

The steps of RNA processing

spliceosomesbullThese are a complexes of 5 snRNA molecules and some145 different proteinsbull The introns in most pre‐mRNAs begin with a GU and endwith an AGbullPresumably these short sequences assist in guiding thespliceosome

Components of Translation

1048766Amino acids1048766The tRNA1048766Aminoacyl-tRNA synthetases1048766The mRNA1048766Competent ribosomes1048766Protein factors1048766ATP and GTP

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

spliceosomesbullThese are a complexes of 5 snRNA molecules and some145 different proteinsbull The introns in most pre‐mRNAs begin with a GU and endwith an AGbullPresumably these short sequences assist in guiding thespliceosome

Components of Translation

1048766Amino acids1048766The tRNA1048766Aminoacyl-tRNA synthetases1048766The mRNA1048766Competent ribosomes1048766Protein factors1048766ATP and GTP

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

Components of Translation

1048766Amino acids1048766The tRNA1048766Aminoacyl-tRNA synthetases1048766The mRNA1048766Competent ribosomes1048766Protein factors1048766ATP and GTP

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

Protein BiosynthesisTranslationGenetic code on mRNA to amino acids on proteinsPolycistronic Vs MonocistronicStepsInitiationElongationTerminationPosttranslational modifications

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

Protein Biosynthesis Initiation-2Initiation complex

Assembly of components oftranslationbullThe mRNAbull2 Ribosomal subunitsbullAminoacyl-tRNAbullGTPbullInitiation factors (IF or eIF)

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

Protein Biosynthesis Initiation-3Initiation complex

AUG for metthionineInitiator tRNA IF-2 and P-siteN-Formylated methioninebullTransformylasebullN10-formyl tetrahydrofolatebullAfter binding to tRNARemoval of N-formyl methionine

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

Protein Biosynthesis Elongation

Addition of amino acids to the carboxyl endElongation factors EF-Tu EF-Ts (eEF)Peptidyltransferase 23S rRNA (ribozyme) and GTPTranslocationbullRibosome moves in 5rsquo-3rsquo on mRNAbullEF-G and GTPbullMovement of uncharged tRNA to E-sitebullMovement of peptidyl-tRNA to P-site

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination

Protein Biosynthesis Termination

Termination codons at the A-siteRF-1 UAA and UAGRF-2 UAA and UGARF 3 Binds GTP

TerminationRelease of newly synthesized polypeptideDissociation of ribosome from mRNARecycling bullRibosomal subunitsbullmRNA and tRNAbullprotein factors

eRF Single release factor Binds GTP

• Chapter 5 protein Biosynthesis
• Gene Expression Transcription
• Gene Transcription DNA rarr RNA
• Slide 4
• Slide 5
• Slide 6
• Types of RNA
• Slide 8
• Slide 9
• Slide 10
• Slide 11
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Slide 16
• Slide 17
• The steps of RNA processing
• Slide 19
• Slide 20
• Components of Translation
• Protein Biosynthesis
• Protein Biosynthesis Initiation-2 Initiation complex
• Protein Biosynthesis Initiation-3 Initiation complex
• Protein Biosynthesis Elongation
• Protein Biosynthesis Termination