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15 Cards in this Set
- Front
- Back
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What are the 5 important features of the genetic code?
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1) read 5' to 3' (N to C terminus)
2) read in triplets (codons) 3) nonoverlapping 4) not punctuated 5) unambiguous |
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What are the 2 most important parts of the tRNA?
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- anticodon loop
- acceptor stem (amino acid is attached) |
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What are the 3 steps of translation?
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1) initiation
2) elongation 3) termination |
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What are the 3 steps of elongation?
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1) Binding of specific tRNA to A site (added from A to P direction)
2) Peptide bond formation (via peptidyl transferase) 3) translocation of mRNA and peptidyl tRNA moves from teh A to the P site and the tRNA in the P site is removed repeat |
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What happens in initiation?
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- mRNA binds to the 2 halves of the rRNA and recruits tRNA with fMet (goes into P site)
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What happens in termination?
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- nonsense/stop codon enters A site
- release factor catalyzes the addition of a water molecule to the peptide chain which hydrolyzes the bond that holds the chain to the last tRNA |
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What is the wobble hypothesis?
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- certain flexibility in binding of tRNA to ribosome-mRNA at the third codon position
- inosine often used in tRNA 3rd position |
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What are 7 examples of post-translational modifications?
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1) protein folding
2) protein/protein interactions 3) remove N-terminal methionine 4) removal of signal sequences in ER 5) glycosylation secreted proteins in golgi 6) ubiquination (targets for degradation in proteosome) 7) phosphorylation/ acetylation/methylation/biotinlation |
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How does tetracycline work?
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- inhibits binding of aminoacyl tRNA to ribosome
- inhibits elongation |
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How does streptomycin work?
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- inhibits initiation and causes misreadings of mRNA
- inhibits initiaiton and elongation |
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How does chloramphenicol work?
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- inhibits elongation by acting as a competitive inhibitor of peptidyltransferase activity (can't form bonds)
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How does erythromycin work?
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- blocks translocation step in chain elongation
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How does puromycin work?
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- premature chain termination by acting as an analog of aminoacyl-tRNA
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What are the 3 mutations that were discussed?
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1) missense (replaces codon for one amino acid with codon for a different one)
2) nonsense (replaces codon for amino acid with stop codon) 3) frameshift (adds/subtracts nucleotides not in steps of and changes reading frame) |
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How do secreted proteins get targeted for surface?
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- secreted proteins have hydrophobic area (signal peptide) that is recognized by signal recognition particle (ribonuclear complex)
- complex docks on peptide and requires ribosome that is translating the peptide to dock on the ER - peptide is complete it is folded in ER - goes to golgi->vessicle->cell surface |
