the language of nucleic acids will be translated into the language of amino acids from nucleotide...
TRANSCRIPT
• The language of nucleic acids will betranslated into the language of amino acids
From Nucleotide Sequence toAmino Acid Sequence
• What is the language of nucleic acids?
DNA molecule
Translation
Polypeptide
Gene 1
Gene 2
Gene 3
DNA strand
Transcription
RNA
Codon
Amino acid
• When DNA is transcribed theresult is an RNA molecule
• RNA is then translated into a sequenceof amino acids in a polypeptide
• Triplets of bases
– are called codons and they specify all the amino acids
• The genetic code is the set of rules translating nucleotide sequence to amino acid sequence
The Genetic Code – our translating dictionary
Transcription: From DNA to RNA
• In transcription
– genetic information is copied from DNA to RNA
– RNA molecule is transcribed from a DNA template
RNApolymerase
RNA nucleotides
Newly madeRNA Direction of
transcriptionTemplatestrand of DNA
(a) A close-up view of transcription
• The “start transcribing” signal is anucleotide sequence called a promoter
Three Phases of Transcription
• The first phase of transcription is Initiation
• The second phase of transcription is Elongation
• The third phase of transcription is Termination
• Translation
Translation: The Players
– conversion from the nucleic acidlanguage to the protein language
• mRNA
Messenger RNA (mRNA)
– message sent from the DNA in the nucleusout into the cytoplasm, to the ribosomes
• tRNA
Transfer RNA (tRNA)
– carriesamino acids
– matches codons with anticodons
Amino acid attachment site
Hydrogen bond
RNA polynucleotide chain
AnticodonAnticodon
• Ribosomes
Ribosomes
– organelles that make proteins
– made of two protein subunits
tRNAbinding sites
P site A site
P A
Largesubunit
mRNAbindingsite
Smallsubunit
(a)
• Translation is divided into three phases
Translation: The Process
– Initiation
– Elongation
– Termination
• A fully assembled ribosome holds tRNA and mRNA for use in translation
Next amino acidto be added topolypeptide
Growingpolypeptide
mRNA
tRNA
• The DNA of two people of the same sex is over 99% identical
• Animals, plants, and bacteria can be genetically modified to produce human proteins
CHAPTER 11 – DNA TECHNOLOGY
• DNA technology has created many advances
BIOLOGY AND SOCIETY: HUNTING FOR GENES
– Genetically Modified (GM) food
– DNA fingerprinting
– Human Genome Project
• Put a gene into a bacterium and its proteinscan be produced in large quantities
From Medicine to Food
• DNA technology replaces plant-breeding programs
Genetically Modified (GM) Foods
– half of American crops of soybeans and corn are GM
• Bacteria are the workhorses
Recombinant DNA Techniques
• Biologists use bacterial plasmids– small, circular DNA molecules
1
2
3
Gene for pest resistanceinserted into plants
Protein dissolves blood clotsin heart attack therapy
Cell containing geneof interest
Host cell
Gene ofinterest
DNA
Recombinant DNA(host DNA plusgene of interest)
Cell multiplies andproduces protein
Genes may be insertedinto another organism Protein may be harvested
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