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35 Cards in this Set
- Front
- Back
- 3rd side (hint)
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what is the shape of the structure of tRNA when drawn out? What is its real 3D shape?
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clover leaf; L
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what is the name of the tRNA portion which binds the AA? The portion which recognizes mRNA sequences?
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acceptor stem; anticodon loop
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which end of the AA is bound to which end of the tRNA molecule? Which type of bond is this?
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carboxyl on AA to 3' OH on tRNA; covalent
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is tRNA binding to mRNA parallel or antiparallel?
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antiparallel (5' tRNA binds to 3' mRNA)
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what are the sizes of the large and small eukaryotic ribosomal subunits?
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40S, 60S
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which step in translation is known as the primary specificity step? Why?
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activation; once AA is loaded onto proper tRNA, identity of AA is never checked again
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what is the name for the enzyme which catalyzes activation of translation?
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aminoacyl tRNA synthetase
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is the aminoacyl tRNA synthetase specific to the AA or to the anticodon?
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AA, there is usually one aminoacyl tRNA synthetase per AA
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None
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what drives the reaction of aminoacyl tRNA synthetase?
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hydrolysis of PPi
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None
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initiation factors promote the association of which tRNA with the 40S ribosomal subunit? Which initiation factor is especially helpful in this reaction?
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Methionine; IF2
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following association of Met tRNA with 40S subunit, what is next step in initiation? The interaction of which two initiation factors takes place here?
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several other intiation factors recognize guanosine cap on mRNA and recruit 40S to 5' end of mRNA; IF2 and IF4e
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what is the final step of initiation following binding of Met tRNA to 40S and binding of 40S to guanine cap of mRNA?
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40S scans down mRNA and initiates transcription at first AUG codon on sequence.
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vanishing white matter disease is caused by a mutation in which protein?
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IF2b
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what are the names of the 3 sites on the large subunit ribosomes?
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A site, P site, E site
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at which site on large ribosomal subunit do loaded tRNA's enter?
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A site
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at which site on large ribosomal subunit does first tRNA enter?
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P site
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in elongation, a peptide bond is formed between amino acid in the _____ site and the peptide in the ____ site.
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A;P
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mRNA is read in which direction?
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5' to 3'
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what is the name of the class of proteins which read the stop codon?
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release factors
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release factors mimic the shape of which molecules?
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tRNAs
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what happens when a stop codon appears in the A site?
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release factors enter and trigger peptidyl transferase to transfer growing peptide to water instead of to aminoacyl tRNA
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what are 3 major differences between prokaryotic and eukaryotic translation?
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prokaryotic translation is coupled with transcription (in euks, no coupling), ribosome sizes in prokaryotes 50S+30S (in euks, 40S+60S), initiation via S-D sequence and fMet in proks (initiaition via scanning from 5' cap and no fMet in euks)
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the degeneracy of the genetic code is accounted for mostly by which phenomenon?
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wobble
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in which position on the codon is wobbling most frequent? With which enzyme is wobble associated?
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5'-most position; aminoacyl tRNA synthetase
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different tRNAs for the same AA are called what?
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isoacceptors
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what are the codes for the three stop codons?
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UAA, UAG, UGA
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what is missense mutation? A silent mutation?
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when one nucleotide is erroneously inserted, changing one AA in peptide; when nucleotide changes but does not effect protein change.
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what is a nonsense mutation?
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when a nucleotide change prematurely truncates a protein by changing a normal codon to a stop codon
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do frameshift mutations normally lead to premature truncations?
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yes
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which type of gene products does mtDNA code?
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rRNA, tRNA, subunits of respiratory chain
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defects in which type of tissue is most common in mtDNA mutations?
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muscle
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mutation of mt tRNA genes is respondible for which two syndromes?
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MERRF, MELAS
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GTP is needed for which two steps of elongation?
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addition of tRNA to A site and translocation of peptide to P site
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which elongation factor is essential in ensuring the right tRNA is inserted in the A site?
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EF-Tu
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peptidyl transferase activity of ribosome is attributed to rRNA or proteins?
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rRNA
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