Which of the following is not a common posttranscriptional modification of tRNA molecules?
A. removal of nucleotides from the 5' and 3' ends
B. methylation and deamination of specific bases
C. addition of a 5' cap
D. attachment of the C-5 of uracil to the ribose at specific sequences
Which of the following does not contribute significantly to DNA damage?
A. deamination due to hydrolysis
B. alkylation of bases
C. deamination due to superoxide radicals
D. oxidation by hydroxyl radicals
E. oxidation by hydrogen peroxide (H2O2)
Which of the following best explains why not all individual aminoacyl-tRNA synthetase enzymes recognize the correct tRNA molecules through the anticodon sequence?
A. All tRNA molecules have the same anticodon sequence.
B. Synthetases only contact the tRNA molecules at the 3'-terminal hydroxyl.
C. More than one codon may code for one amino acid.
D. There are 61 different aminoacyl-tRNA synthetase enzymes.
The function of telomeres can be best described as:
A. attachment sites for the proteins of the kinetochore.
B. sequences at the ends of the linear eukaryotic chromosome that protect the ends from proteases.
C. sequences of the eukaryotic chromosome that ensure proper distribution during mitosis.
D. sequences of the bacterial chromosome that ensure proper distribution during binary fission.
E. the sites at which replication initiates.
Recycling of used eIF2 (eIF2-GDP), after it has served its rolein translation initiation, is facilitated by:
A. dephosphorylation of eIF2.
B. phosphorylation of the GDP on eIF2 to recreate the active eIF2-GTP.
C. release of the GDP by a guanine nucleotide exchange factor.
D. dephosphorylation of eIF2.
Quick Reply
