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15 Cards in this Set
- Front
- Back
What direction is mRNA read and with what end does the polypeptide chain start?
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mRNA is read 5' to 3' and the protein is translated starting with amino terminus.
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Initiation Codon
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First AUG down from the 5' end, therefore, methionine.
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Stop Codons
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Sometimes called nonsense codons. Cause termination of polypeptide chain:
UAA, UAG, UGA |
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Initiation factors
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Promote assembly of robosomal subunits, mRNA, and initiator tRNA.
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Elongation factors
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Match each tRNA to the codon in the aminoacyl site of ribosome and promote ratcheting of RNA.
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Release factors
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Act to terminate translation when a stop codon is reached. Acts by transferring the C-terminus of the protein to a water molecule.
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Polyribosomes
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Also known as a polysome. Name of multiple ribosomes which engage the same mRNA simultaneously.
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Wobble base
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3rd base of an anticodon on tRNA which can recognize more than one base on the mRNA. The base which enables this wobbles is often inosine. Occurs at the 3' portion of the mRNA (therefore the 5' portion of the anticodon).
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What proteins undergo proteolytic processing?
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Proteins destined for extracellular transport.
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Signal Sequences
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N terminal sequence which plays a role in targeting proteins and their ribosomes to membranes. Usually rich in hydrophobic AAs.
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Tetracyclines
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Antibiotic which inhibits the binding of aminoacyl tRNAs to ribosome.
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Streptomycin
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Antibiotic which inhibits initiation and causes misreading of mRNA so mostly defective proteins are synthesized.
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Chloramphenicol
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Antibiotic which acts to inhibit chain elongation by acting as a competitive inhibitor of the peptidyltransferase activity of the bacterial large rbosomal subunit. Contains an amide link resembling a peptide bond.
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Erythromycin
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Antibiotic which blocks translocation step in chain elongation by binding to a specific region of the bacterial large ribosomal subunit.
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Puromycin
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Antibiotic which causes premature chain termination by acting as a structural analog of aminoacyl tRNA.
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