Protein Synthesis:

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Lecture 16 Protein Synthesis Translation of
the Genetic Message Chapter 12
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Translating the Genetic Message

• General steps in protein synthesis.
• The genetic code.
• Chain initiation.
• Chain elongation.
• Chanin termination.

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Aminoacyl-tRNA
mRNA aminoacyl-tRNA bind to ribosome
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Initiation Need 30s ribosome Fmet-tRNAfmet mRNA
GTP Initiation factors.
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30s Ribosome
50s ribosome
GTP? GDP P
3 sites
70s initiation complex
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How does the mRNA know where to bind and where
will initiation begin.
Shine-Dalgarno sequences.
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Elongation
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A aminoacyl site P peptidyl site E exit site
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GTP elongation
factors
Aminoacyl-tRNA
The aminoacyl-tRNA binds to the A site.
GDP P
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Peptidyl transfer
Peptidyl tRNA
Uncharged tRNA
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Translocation
uncharged tRNA GDP P

Elongation factor GTP
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Process continues by adding a new amino acyl
tRNA to the A site.
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Chain termination. UAA, UAG and UGA are stop
signals.
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Chain termination.
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Release factors GTP
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Peptide is released.
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Polysomes
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