The exchange of a purine-pyrimidine base pair for the other purine-pyrimidine pair is:
A. a silent mutation.
B. a transition mutation.
C. a frameshift mutation.
D. a nonsense mutation.
E. a transversion mutation.
Which of the following events is least likely a result of protein phosphorylation?
A. reduction in the activity of an enzyme
B. transport of the protein to the nucleus
C. the specific binding of a regulatory protein
D. targeting of the protein for degradation
Histone chaperones:
A. are required for direct assembly of the 30 nm filament.
B. are acidic proteins that bind individual histones and assemble them into dimer and tetramer forms.
C. can also modify the histones covalently by phosphorylation.
D. are acidic proteins that bind to H2A-H2B dimers and H3-H4 tetramers before assembly into nucleosomes.
E. can also modify the histones covalently by acetylation.
Which of the following is not a function of the Drosophila Sxl protein?
A. prevention of the splicing machinery from recognizing the splice junctions of the E1 or L3 exons of the Sxl mRNA
B. mediation of alternative splicing that produces transcripts for functional Tra protein
C. binding specifically to the regulated 3' splice site of the tra transcript
D. mediation of the splice variant of the dsx transcript leading to repression of female-specific genes
Which of the following is an enzyme used in cloning that breaks covalent bonds?
A. DNA ligase
B. restriction endonuclease
C. reverse transcriptase
D. DNA polymerase I
E. polynucleotide kinase
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