Genetic Code and Translation

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Genetic Code and Translation
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Outline

• Concepts and Terms related to genetic code
• Wobble
• Degeneracy
• isoaccepting
• Translation
• prokaryote
• eukaryotes

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Amino Acid
Transfer RNA
ribosome
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Genetic Code Table 1968
Wobble
Degeneracy mRNA
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Isoaccepting tRNAs
Different tRNAs accept same amino acid!
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We will focus our discussion of translation as a
Nonoverlapping Code
mRNA sequences
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Animation of Prokaryotes Translation
http//highered.mcgraw-hill.com/sites/0072437316/s
tudent_view0/chapter14/animations.html
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Steps of Translation

• 1. Binding of amino acids to tRNA
• 2. Initiation
• 3. Elongation
• 4. Termination
• 5. Peptide Release
• 6. Protein modification

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Step 1 Binding of amino acid to tRNA
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It takes two steps to charge the tRNA
Aminoacyl-tRNA-synthetase
(proofreading activity)
Amino acidATP
tRNA is charged
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Up close view of charged tRNA
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Bacterial Initiation
Step 2 Initiation of Translation
IF3
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30S
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Note 3 ribosomal sites
P
A
E
70S
E
A
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Kozak
Eukaryotic Initiation key differences
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3. ELONGATION look at the EPA sites
Peptidyl transferase
(ribozyme of large subunit)
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Up close view of translation
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Elongation continues on ribosomes
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UAA UAG UGA
Steps 4 and 5
Termination and Release
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6.
Lipoprotein
Glycoprotein
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Many antibiotics target prokaryotic translation.
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Antibiotics and Translation

• Bind and block bacterial ribosomes A site
• Binds to large subunit blocks peptide formation
• Blocks initiation step
• Blocks translocation step

• Tetracyclines
• Chloramphenicol
• Streptoymycin
• Erythromycin

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For your review Summary of important steps
involved in translation
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1.
2.
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3.
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4.
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5.
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6. Protein Modifications
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Eukaryotic translation is very similar except

• More IFs
• Kozak sequence
• 5CAP
• 3poly-A tail

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