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27 Cards in this Set
- Front
- Back
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In tRNA, where is the site for attachment of specific AA?
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on the OH on the 5' end
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What portion of tRNA determines which AA can be attached?
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Anticodon region
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What does it mean that the DNA code is degenerate?
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1 codon codes for only 1 AA, but 1AA can have several different codons
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What attaches the correct AA to tRNA w/ the matching anticodon?
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Family of enzymes called aminoacyl-tRNA syntheases
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What is an amino acid bound to tRNA called?
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aminoacyl-tRNA
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What is a polysome?
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Multiple ribosomes acting on one strand of mRNA
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What is a prokaryotic mRNA which contains code for several proteins called?
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polycistronic
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How is translation intiated?
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Shine-Delgarno sequence, then the start codon (AUG!)
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What is the purpose of the shine-delgarno sequence?
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It base pairs w/ a portion of the 12s rRNA and aligns the AUG on small subunit
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What recognizes AUG by initiator tRNA?
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IF2 or eIF2
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What is initiator tRNA?
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tRNA w/ anticodon CAU, it binds AA methionine
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What is the mode of action of the antibiotic streptomycin?
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Binds 30s subunit, distorts its structure and blocks initiation
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What does binding of met-tRNA prompt?
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Release of IF1, IF2, and IF3; Hydrolysis of GTP, Attachment of the 50s subunit
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What are the 2 domains of the 50s subunit?
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P and A Site;
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What does the P-Site of the 502 subunit contain?
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Region where initiatio tRNA projects, will contain emerging polypeptide
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What does the A-site of the 50s subunit contain?
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Adjacent to P-site, next codon resides there
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How is the appropriate aminoacyl-tRNA transported to the A-site?
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Elongation Factor, GTP is hydrolyzed in the process
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What is the function of peptidyl Transferase?
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Break AA from tRNA and move fmet to A-site
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What does Chloramphenicol do?
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inhibits peptidyltransferase in prokaryotes
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What does Cyclohexmide do?
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inhibits peptidytransferase in eukaryotes
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What does puromycin do?
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occupies the a-site and leads to premature termination in pro and eukaryotes
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What does Translocase do?
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prompts hydrolysis of GTP which slides the ribosome 3 nucleotides in the 3' direction
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What do Clindamycin and erythromycin do?
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irreversibly bind and inhibit translocase
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What does diptheria toxin do?
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inactivates eEF2 inhibiting eukaryotic elongation
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How many ~P's are required to add one AA?
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4!
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What is the primary energy donor in protein synthesis?
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GTP
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When does elongation stop?
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Then one stop codon (UAA, UAG, or UGA) is at the A-site
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