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35 Cards in this Set

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what is the shape of the structure of tRNA when drawn out? What is its real 3D shape?
clover leaf; L
what is the name of the tRNA portion which binds the AA? The portion which recognizes mRNA sequences?
acceptor stem; anticodon loop
which end of the AA is bound to which end of the tRNA molecule? Which type of bond is this?
carboxyl on AA to 3' OH on tRNA; covalent
is tRNA binding to mRNA parallel or antiparallel?
antiparallel (5' tRNA binds to 3' mRNA)
what are the sizes of the large and small eukaryotic ribosomal subunits?
40S, 60S
which step in translation is known as the primary specificity step? Why?
activation; once AA is loaded onto proper tRNA, identity of AA is never checked again
what is the name for the enzyme which catalyzes activation of translation?
aminoacyl tRNA synthetase
is the aminoacyl tRNA synthetase specific to the AA or to the anticodon?
AA, there is usually one aminoacyl tRNA synthetase per AA
what drives the reaction of aminoacyl tRNA synthetase?
hydrolysis of PPi
initiation factors promote the association of which tRNA with the 40S ribosomal subunit? Which initiation factor is especially helpful in this reaction?
Methionine; IF2
following association of Met tRNA with 40S subunit, what is next step in initiation? The interaction of which two initiation factors takes place here?
several other intiation factors recognize guanosine cap on mRNA and recruit 40S to 5' end of mRNA; IF2 and IF4e
what is the final step of initiation following binding of Met tRNA to 40S and binding of 40S to guanine cap of mRNA?
40S scans down mRNA and initiates transcription at first AUG codon on sequence.
vanishing white matter disease is caused by a mutation in which protein?
what are the names of the 3 sites on the large subunit ribosomes?
A site, P site, E site
at which site on large ribosomal subunit do loaded tRNA's enter?
A site
at which site on large ribosomal subunit does first tRNA enter?
P site
in elongation, a peptide bond is formed between amino acid in the _____ site and the peptide in the ____ site.
mRNA is read in which direction?
5' to 3'
what is the name of the class of proteins which read the stop codon?
release factors
release factors mimic the shape of which molecules?
what happens when a stop codon appears in the A site?
release factors enter and trigger peptidyl transferase to transfer growing peptide to water instead of to aminoacyl tRNA
what are 3 major differences between prokaryotic and eukaryotic translation?
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)
the degeneracy of the genetic code is accounted for mostly by which phenomenon?
in which position on the codon is wobbling most frequent? With which enzyme is wobble associated?
5'-most position; aminoacyl tRNA synthetase
different tRNAs for the same AA are called what?
what are the codes for the three stop codons?
what is missense mutation? A silent mutation?
when one nucleotide is erroneously inserted, changing one AA in peptide; when nucleotide changes but does not effect protein change.
what is a nonsense mutation?
when a nucleotide change prematurely truncates a protein by changing a normal codon to a stop codon
do frameshift mutations normally lead to premature truncations?
which type of gene products does mtDNA code?
rRNA, tRNA, subunits of respiratory chain
defects in which type of tissue is most common in mtDNA mutations?
mutation of mt tRNA genes is respondible for which two syndromes?
GTP is needed for which two steps of elongation?
addition of tRNA to A site and translocation of peptide to P site
which elongation factor is essential in ensuring the right tRNA is inserted in the A site?
peptidyl transferase activity of ribosome is attributed to rRNA or proteins?