Gene Translation: RNA ? Protein

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Chapter 4 Gene Translation RNA ? Protein
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4.1 Translation System 1. Genetic codon
? Degeneracy ? Generality ? Particularity ?
Codon Anticodon
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Wobble hypothesis
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2. mRNA structure mRNA structure of
prokaryotes polycistron
Shine-Dalgarno sequence
mRNA structure of eukaryotes single
cistron 5-cap 3-poly(A)
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3. tRNA
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tertiary structure
Upside-down L (?L?)
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5. Ribosome
size of ribosome Size of subunits Ratio (RNA protein)
prokaryotes 70S 50S, 30S 2 1
mammalian 80S 60S, 40S 3 2
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4.2 Protein Synthesis in Prokaryotes
Initiation 1?Ribosome 30S subunit 2?template
mRNA 3?fMet-tRNAfMet 4?IF-1, IF-2, IF-3 5?GTP 6?
Ribosome 50S subunit 7?Mg2
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Initiation
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Elongation aa-tRNA ?A site
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Formation of Peptide Bond
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Translocation
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Elongation of peptide chain
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RE1, RF2, or RF3 Termination of translation
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Peptide chain released
Animation
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4.3 Protein Synthesis in Eukaryotes
Initiation
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Processing of Nascent Protein ? Removing
fMet or Met ? Formation of S-S bond
? Chemical modification of amino acid ?
Intein splicing
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The Mechanism of Protein Splicing
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4.4 Molecular Chaperone
1. Functions of Chaperones
2. Main Types of Chaperones ? molecular
chaperone ? chaperonin ? trigger
factor
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? Chaperonins
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? Trigger Factor in E. coli
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4.5 Transmembrane Transport of Protein
Signal Hypothesis ? Signal
peptide, ? SRP ?
DP ? Signal peptidase
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Model for the translocation of proteins into the
endoplasmic reticulum in eukaryotes
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4.6 Protein Degradation 1. Ubiquitin
(1) Components of Ubiquitin
(2) Ubiquitination
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2. Proteasomes
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3. Protein Degradation Pathways (1)
Ubiquitin-dependent degradation (2)
Ubiquitin-independent degradation
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Summary 1. Structure of tRNA and ribosome 2.
Procedures of protein translation 3.
Differences between prokaryotic and
eukaryotic translation 4. What is the function
of intein splicing? 5. Types of molecular
chaperone and their functions 6. What is signal
peptide? What is signal hypothesis? 7. Ubiquitin
and mechanism of protein degradation
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