What is the role of Rad51 in eukaryotic recombination events?
A. It introduces single-strand breaks in the chromosome.
B. It degrades the 5'-ending strand to create 3'-ending single-strand overhangs.
C. It is a helicase that assists in separating the DNA strands at the site of breakage.
D. It is a single-strand DNA binding protein that coats the 3'-ending single-strand overhang.
E. It is a RecA-class recombinase that mediates strand invasion.
Which of the following features of DNA organization do eukaryotes and bacteria have in common (select all correct choices)?
A. DNA is associated with basic proteins.
B. DNA is found within a 30 nm filament.
C. DNA breakage in one loop will not affect DNA in other loops.
D. A change of supercoiling in a cleaved loop would not affect other loops.
E. Under electron microscope, DNA will have a beads-on-a-string appearance.
Which of the following is true of introns?
A. RNA II polymerase transcribes the intronsequences along with exon sequences.
B. More DNA of the human genome is devoted to exons than to introns.
C. Introns are not found in bacteria or archaea, only eukaryotes.
D. When annealing mature mRNA to corresponding chromosomal DNA sequences, the mRNA will form loops with intron sequences looped out.
What is the role of RPA in eukaryotic recombination events?
A. It introduces single-strand breaks in the chromosome.
B. It degrades the 5'-ending strand to create 3'-ending single-strand overhangs.
C. It is a helicase that assists in separating the DNA strands at the site of breakage.
D. It is a single-strand DNA binding protein that coats the 3'-ending single-strand overhang.
E. It is a RecA-class recombinase that mediates strand invasion.
Which of the following may be a reason for bacteria not having nucleosomelike structures?
A. Bacteria need to respond quickly to the environment and therefore need ready access to the genome.
B. Cell division in bacteria occurs in as little as 15 minutes.
C. A much larger proportion of the bacterial chromosome codes for proteins.
D. Higher rates of metabolism in bacteria mean that a much larger proportion of the DNA is being transcribed or replicated at a given time.
E. All of these choices are correct.
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