Translation and Operons
You Should Be Able To 1. Describe the three stages translation. including the movement of trna molecules through the ribosome. 2. Compare and contrast the roles of three different types of RNA during translation. 3. Describe the roles of signal peptides in protein synthesis. 4. Describe the regulation of gene expression, using the lac or trp operon as an example.
Fig. 17-3a-2 TRANSCRIPTION TRANSLATION DNA mrna Ribosome Polypeptide (a) Bacterial cell
Fig. 17-3b-3 Nuclear envelope TRANSCRIPTION DNA RNA PROCESSING Pre-mRNA mrna TRANSLATION Ribosome Polypeptide (b) Eukaryotic cell
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2011 Pearson Education, Inc.
Three Stages of Translation Three Stages of Translation Initiation Elongation Termination
1 2011 Pearson Education, Inc.
Also, note that this constitutes 5 Untranslated Region (UTR) of the mrna J 1 2011 Pearson Education, Inc.
1 2 3 2011 Pearson Education, Inc.
trna: Transfer RNA
Transfer RNA (trna)
Transfer RNA (trna) Single-stranded RNAs of about 74-95 nucleotides On one end, they hold an amino acid On the other end, they bind to mrna
64 Codons 2011 Pearson Education, Inc.
Transfer RNA (trna) There are about 45 different trnas in eukaryotic cells The code is conservative!
The Wobble Hypothesis
trna Structure Campbell 8e, Fig. 17.14
Aminoacyl trnasynthetase 2011 Pearson Education, Inc.
Charging Transfer RNA Aminoacyl trna Synthetase + Amino acid + ATP + Uncharged trna = Charged trna Campbell 8e, Fig. 17.15
Ribosomes and Translation Three Stages of Translation Initiation Elongation Termination
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Elongation
Ribosomes and Translation Three Stages of Translation Initiation Elongation Termination
Termination Termination 2011 Pearson Education, Inc.
Signal Peptides Campbell 8e, Fig. 17.21
Regulation of gene expression in prokaryotes.
Operon A series of genes sharing a promoter and a regulatory region. Regulatory Region A region that can produce proteins to inhibit or stimulate gene expression.
The Operon
Operon A series of genes sharing a promoter and a regulatory region. Regulatory Region A region that can produce proteins to inhibit or stimulate gene expression.
trp operon
Fig. 18-3b-2 DNA No RNA made mrna Protein Tryptophan (corepressor) Active repressor (b) Tryptophan present, repressor active, operon off
Fig. 18-3a trp operon DNA Promoter Regulatory gene mrna Protein 5 trpr trpe trpd trpc trpb Operator Start codon Stop codon 3 RNA mrna 5 polymerase E D C B Inactive repressor Promoter (a) Tryptophan absent, repressor inactive, operon on Genes of operon trpa Polypeptide subunits that make up the enzyme tryptophan synthase A
Fig. 18-3 trp operon DNA Promoter Regulatory gene mrna 5 Promoter Genes of operon trpr trpe trpd trpc trpb Operator Start codon Stop codon 3 RNA mrna 5 polymerase E D C B Protein Inactive Polypeptide subunits that make up repressor enzymes for tryptophan synthase (a) Tryptophan absent, repressor inactive, operon on trpa A DNA No RNA made mrna Protein Tryptophan (corepressor) Active repressor (b) Tryptophan present, repressor active, operon off
lac operon
Fig. 18-3 trp operon DNA Promoter Regulatory gene mrna 5 Promoter Genes of operon trpr trpe trpd trpc trpb Operator Start codon Stop codon 3 RNA mrna 5 polymerase E D C B Protein Inactive Polypeptide subunits that make up repressor enzymes for tryptophan synthase (a) Tryptophan absent, repressor inactive, operon on trpa A DNA No RNA made mrna trp operon Protein Tryptophan (corepressor) Active repressor (b) Tryptophan present, repressor active, operon off
You Should Be Able To 1. Describe the three stages translation. including the movement of trna molecules through the ribosome. 2. Compare and contrast the roles of three different types of RNA during translation. 3. Describe the roles of signal peptides in protein synthesis. 4. Describe the regulation of gene expression, using the lac or trp operon as an example.
Translation and Operons