Term
| What are the two functions of the AUG codon? |
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Definition
| Encodes internal Met and initiation signal |
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Term
| What are unique/necessary structural features of tRNA? |
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Definition
| tRNA has a secondary (cloverleaf) structure |
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Term
| What is the wobble hypothesis? |
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Definition
wobble hypothesis implies tRNA anticodon can base pair with more than 1 codon
3rd anticodon position often modified with formation of non-WC base pairs |
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Term
| One tRNA can recognize several degenerate base pairs...what hypothesis is closely associated with this fact? |
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Definition
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Term
| Define the terms missense mutation, nonsense mutation, and silence mutation |
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Definition
missense - functional mutation where change of amino acid code occurs - change of 1st or 2nd base
nonsense - functional change of stop codon
silence - functional change where amino acid code unchanged - usually 3rd aa |
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Term
| How could a frameshift be caused? |
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Definition
| An insertion or deletion mutation where a different protein is involved |
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Term
| how do organisms (prokaryotes v eukaryotes) ensure that the correct reading frame is used? |
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Definition
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Term
| Which enzyme aminoacylates tRNA and how is amino acid specificity and tRNA specificity ensured? |
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Definition
aminoacyl-tRNA synthetases - tyrosyle-tRNA synthetase (lowers the transitional state)
ensured by additional proofreading step of hydrolysis |
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Term
| What are ribosomes (structurally and functionally)? |
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Definition
| Ribosomes are sites of protein synthesis made of large and small subunits |
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Term
| What are the ribosome components in prokaryotes and eukaryotes? |
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Definition
Prokaryotes - protein synthesis at ribosomes
eukaryotes - free ribosomes and membrane bound ribosomes (where protein synthesis occurs) |
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Term
| In which direction does protein synthesis occur? |
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Definition
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Term
| Name the steps in protein synthesis |
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Definition
Initiation
Elongation
Termination
Posttranslational modification |
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Term
| What are the major differences in the initation of ribosomal protein biosyntehsis between prokaryotes and eukaryotes with respect to the N-terminal residue and the selection of translation start site? |
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Definition
| the initiator tRNA in prokaryotes are fMet - specific formylation of tRNA and N terminal peptide residue where eukaryotes are initated by Met-tRNA (nor fomylated) |
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Term
| What is the function of the Shine Dalgarno sequence and how is it being recognized by the ribosome? |
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Definition
| helps selection of translation start site and is recognized by the lbsrRNA - WC base pair w/ SD seq |
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