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31 Cards in this Set
- Front
- Back
what binds initially to the peptidyl site in the 80s ribosome?
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Met-tRNA
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what binds to the A site in the 80s ribosome?
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aminoacyl-tRNAs
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E site (exit site) is for ...
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“used” tRNAs that have already transferred their amino acids to peptide chain
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in the first step of elongation, incoming aminoacyl-tRNA first combines with ... and ...
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elongation factor EF1α
GTP |
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aminoacyl-tRNA-EF1α-GTP complex binds to ... where GTP is ... and EF1α-GDP dissociates from the tRNA
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A site
hydrolyzed |
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where does proofreading occur in translation?
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A site
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amino acid on tRNA in A site forms peptide bond with amino acid on tRNA in P site and is catalyzed by ...
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peptidyltransferase
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peptidyltransferase can be found where?
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large ribosomal subunit
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elongation of the newly forming protein involves the formation of ... bonds
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peptide
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in translocation, ... complexes with ... and binds the ribosome causing a conformational change that moves mRNA and paired tRNA to the ...
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EF2
GTP E site |
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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
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... binds to the ribosome when a stop codon is encountered on the mRNA, causing ... to hydrolyze bond between peptide chain and tRNA
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release factor
peptidyltransferase |
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in translation, where does the release factor bind to?
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A site on the large ribosome subunit
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what is the energy requirement to form each aminoacyl-tRNA?
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2 phosphate bonds from ATP
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what is the energy requirement to form the pre-initiation complex?
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hydrolysis of GTP
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what is the energy requirement to add each amino acid to the growing peptide chain?
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2 GTP’s
(one with EF1, one with EF2) |
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what is a polysome?
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complex of many ribosomes simultaneously translating a single mRNA
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what is the size of prokaryotic ribosomes?
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70S ribosome (30S+50S)
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how does Met-tRNA in prokaryotes differ from that of eukaryotes?
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it is formylated
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what are the initiation factors needed in prokaryote translation?
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IF-1, IF-2, IF-3
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bacterial mRNA (is/is not) capped
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is not
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what is the significance of the Shine-Dalgarno sequence in prokaryotic mRNA?
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Identification of start AUG codon occurs when the Shine-Dalgarno sequence in the mRNA binds to its complementary sequence on the small ribosomal subunit.
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what is MELAS?
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mutations in mitochondrial tRNA that involve defective mitochondrial tRNA(Leu)
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what are the symptoms in MELAS?
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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 |
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... of all inherited diseases result from premature termination codon (PTC) mutations
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1/3
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Duchenne muscular dystrophy is caused by ...
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premature translation termination of the dystrophin protein in muscle cells
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Cystic Fibrosis is caused by ...
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nonsense mutations in the cystic fibrosis transmembrane regulator (CFTR) gene
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cancer may be caused by ...
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PTC mutations in tumor-suppressor genes
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what is a nonsense mutation?
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a premature stop codon is transcribed in the mRNA
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what are the two major therapeutic approaches to overcome nonsense PTC mutations?
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gene therapy
Pharmacological approaches |
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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
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aminoglycosides
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