Transcript Ch 15. Genetic Code and Translation

Genetic Code and Translation
Outline
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Concepts and Terms related to genetic code
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Wobble
Degeneracy
isoaccepting
Translation
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prokaryote
eukaryotes
Amino Acid
Transfer RNA
ribosome
Genetic Code Table
1968
Wobble
Degeneracy
& mRNA
Isoaccepting & tRNAs
Different tRNAs
accept same amino
acid!
We will focus our discussion of translation as a “Nonoverlapping Code”
mRNA sequences
Animation of Prokaryotes Translation
http://highered.mcgrawhill.com/sites/0072437316/student_view0/chapter14/animations.html
Steps of Translation
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1. Binding of amino
acids to tRNA
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2. Initiation
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3. Elongation
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4. Termination
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5. Peptide Release
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6. Protein modification
Step 1 Binding of amino acid to tRNA
It takes two steps to “charge” the tRNA
(proofreading activity)
Amino acid+ATP
Aminoacyl-tRNA-synthetase
tRNA is charged
Up close view of “charged” tRNA
Step 2: Initiation of Translation
IF3
Bacterial Initiation
30S
Note 3 ribosomal sites
E P A
E
70S
A
Kozak
Eukaryotic Initiation
key differences
3. ELONGATION: look at the “EPA” sites
Peptidyl transferase
(ribozyme of large subunit)
Up close view of translation
Elongation continues on ribosomes
Steps 4 and 5:
Termination and Release
UAA
UAG
UGA
6.
Lipoprotein
Glycoprotein
Many antibiotics target prokaryotic
translation.
Antibiotics and Translation
Tetracyclines
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Bind and block bacterial ribosomes “A” sit
Chloramphenicol Binds to large subunit; blocks peptide
formation
Streptoymycin
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Blocks initiation step
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Blocks translocation step
Erythromycin
Review: The Structure and
Function of Proteins
Protein: Levels of structural organization
For your review:
Summary of important steps involved in translation
1.
2.
3.
4.
5.
6. Protein Modifications
Eukaryotic translation is very
similar except:
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More IF’s
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Kozak sequence
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5’CAP
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3’poly-A tail