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31 Cards in this Set

  • Front
  • Back
what binds initially to the peptidyl site in the 80s ribosome?
what binds to the A site in the 80s ribosome?
E site (exit site) is for ...
“used” tRNAs that have already transferred their amino acids to peptide chain
in the first step of elongation, incoming aminoacyl-tRNA first combines with ... and ...
elongation factor EF1α
aminoacyl-tRNA-EF1α-GTP complex binds to ... where GTP is ... and EF1α-GDP dissociates from the tRNA
A site
where does proofreading occur in translation?
A site
amino acid on tRNA in A site forms peptide bond with amino acid on tRNA in P site and is catalyzed by ...
peptidyltransferase can be found where?
large ribosomal subunit
elongation of the newly forming protein involves the formation of ... bonds
in translocation, ... complexes with ... and binds the ribosome causing a conformational change that moves mRNA and paired tRNA to the ...
E site
for translation, place the following reactions in the correct order:
a.peptidyl transferase
b.EF1α + GTP --> EF1α + GDP + Pi
c. EF2 + GTP translocation --> EF2 + GDP + Pi
b, a, c
... binds to the ribosome when a stop codon is encountered on the mRNA, causing ... to hydrolyze bond between peptide chain and tRNA
release factor
in translation, where does the release factor bind to?
A site on the large ribosome subunit
what is the energy requirement to form each aminoacyl-tRNA?
2 phosphate bonds from ATP
what is the energy requirement to form the pre-initiation complex?
hydrolysis of GTP
what is the energy requirement to add each amino acid to the growing peptide chain?
2 GTP’s
(one with EF1, one with EF2)
what is a polysome?
complex of many ribosomes simultaneously translating a single mRNA
what is the size of prokaryotic ribosomes?
70S ribosome (30S+50S)
how does Met-tRNA in prokaryotes differ from that of eukaryotes?
it is formylated
what are the initiation factors needed in prokaryote translation?
IF-1, IF-2, IF-3
bacterial mRNA (is/is not) capped
is not
what is the significance of the Shine-Dalgarno sequence in prokaryotic mRNA?
Identification of start AUG codon occurs when the Shine-Dalgarno sequence in the mRNA binds to its complementary sequence on the small ribosomal subunit.
what is MELAS?
mutations in mitochondrial tRNA that involve defective mitochondrial tRNA(Leu)
what are the symptoms in MELAS?
seizures, stroke-like episodes, extrapyramidal movements, autonomic dysfunction, headache, fever and confusion some symptoms mimic Herpes Simplex Encephalitis (HSE) and
plasma or CSF lactic acid levels are typically high
... of all inherited diseases result from premature termination codon (PTC) mutations
Duchenne muscular dystrophy is caused by ...
premature translation termination of the dystrophin protein in muscle cells
Cystic Fibrosis is caused by ...
nonsense mutations in the cystic fibrosis transmembrane regulator (CFTR) gene
cancer may be caused by ...
PTC mutations in tumor-suppressor genes
what is a nonsense mutation?
a premature stop codon is transcribed in the mRNA
what are the two major therapeutic approaches to overcome nonsense PTC mutations?
gene therapy
Pharmacological approaches
classically used as antibiotics and alters the conformation of rRNA, inducing codon misreading that causes either incorporation of an erroneous amino acid at a sense codon or failure of recognition of the stop codon leading to translational read-through