PROTIEN PROTIEN SYNTHESISSYNTHESIS

Dr. Nadia Hasan

Dr. Ahmed Kassem

بسم الله الرحمن الرحيمبسم الله الرحمن الرحيم

PROTIENSPROTIENS

Definition:Definition:Are chains of Are chains of amino acidsamino acids bound bound

together by together by peptide bondspeptide bonds..

General structure of Amino acidGeneral structure of Amino acid

O=C OH

R

C NHHH

General structure of Amino acid General structure of Amino acid and Peptide bondand Peptide bond

COOH

NH2 C

R

COOH

NH2 C

R

General structure of Amino acid General structure of Amino acid and Peptide bondand Peptide bond

COOH

NH2 C

R

COOH

NH2 C

R

H2O

General structure of Amino acid General structure of Amino acid and Peptide bondand Peptide bond

CONH

NH2 C

R

COOH

C

R

The Main Principle Of Protein The Main Principle Of Protein SynthesisSynthesis(Central Dogma of genetics)(Central Dogma of genetics)

DNA RNA Protein

ReplicationTranscription

Translation

DNA StructureDNA Structure

Watson-Crick model Watson-Crick model of DNA.of DNA.

It is double-stranded It is double-stranded polymer of polymer of nucleotides.nucleotides.

DNA StructureDNA Structure

Each Each nucleotidenucleotide consists of:consists of:

Phosphate groupPhosphate groupdeoxyribose sugardeoxyribose sugarNitrogenous Nitrogenous bases. bases.

DNA ReplicationDNA Replication

The main The main requirements arerequirements are: :

•DNA HelicaseDNA Helicase•DNA PolymeraseDNA Polymerase•Free nucleotides Free nucleotides

such as: dTTP, such as: dTTP, dATP, dCTP, dGTPdATP, dCTP, dGTP..

•Unwinding proteinsUnwinding proteins

Structure of RNAStructure of RNA RNA is a single-stranded polymers of RNA is a single-stranded polymers of

nucleotides, the pentose sugar is always nucleotides, the pentose sugar is always riboseribose , and the bases are , and the bases are AAdenine, denine, GGuanine, uanine, CCytosine, and ytosine, and UUracilracil..Types of RNATypes of RNA::a) Precursor RNA ( pre-RNA)a) Precursor RNA ( pre-RNA)..b) Messenger RNA ( m-RNA)b) Messenger RNA ( m-RNA)..c) Transfer RNA ( t-RNA)c) Transfer RNA ( t-RNA)..d) Ribosomal RNA ( r- RNA)d) Ribosomal RNA ( r- RNA)..

Protein synthesisProtein synthesis Starts at Starts at

nucleus by nucleus by formation of formation of mmRNA RNA through through a process a process calledcalled transcriptiontranscription

RNA processingRNA processing

mmRNA RNA is is processed in the processed in the nucleusnucleus

Intron are removed Intron are removed Exons are joinedExons are joined

t-RNAt-RNA = Single strand= Single strand = Bend on = Bend on

itself to form itself to form three loop three loop regions.regions.

= one loop = one loop contains the contains the anticodon. anticodon.

= it carries aa = it carries aa at one end.at one end.

T-RNAT-RNA

Amino acid activationAmino acid activation

Protein synthesis•Requires 3 steps:•Initiation•Elongation•Termination

Translation Translation

Then go to the Then go to the ribosomes in ribosomes in cytoplasm where it’s cytoplasm where it’s genetic code is genetic code is translated into amino translated into amino acids by a process acids by a process called called translationtranslation..

The Genetic Code

UUUUUCUUAUUG

CUUCUCCUACUG

AUUAUCAUAAUG

GUUGUCGUAGUG

UCUUCCUCAUCG

CCUCCCCCACCG

ACUACCACAACG

GCUGCCGCAGCG

UAUUACUAAUAG

CAUCACCAACAG

AAUAACAAAAAG

GAUGACGAAGAG

UGUUGCUGAUGG

CGUCGCCGACGG

AGUAGCAGAAGG

GGUGGCGGAGGG

Phe

Leu

Leu

Val

Ile

Met

Ser

Pro

Thr

Ala

Tyr

Stop

His

Gln

Asn

Lys

Asp

Glu

Cys

Arg

Ser

Arg

Gly

StopTrp