32. During repair of DSB, the use of 3\' ends for the invasion steps has the imp
ID: 214262 • Letter: 3
Question
32. During repair of DSB, the use of 3' ends for the invasion steps has the important consequence that these ends can:
a) be easily ligated together.
b) also correct any mutations that arise during repair.
c) catalyze DNA synthesis.
d) also act as primers for DNA synthesis.
e) All of the answers are correct.
33. Aneuploidy:
a) a condition in which a cell has the wrong number of chromosomes
b) can be caused by misalignment of chromosomes during meiosis I.
c) can be caused by incomplete recombination during meiosis I.
d) is the leading genetic cause of developmental and mental disabilities.
e) All of the answers are correct.
34. Which of the following is NOT true of repairing double-strand breaks by recombination?
a) After invasion of the homologous chromosome, the 3 end of the invading strand acts as a pri mer for DNA synthesis.
b) The broken ends are processed, with the 3-ending strand selectively degraded to create 5' overhangs.
c) The 3' single strand extensions invade the homologous chromosome, displacing the homologous strand and base pairing with the complementary strand.
d) As a result of the two strand invasions, the two homologues are linked at two places and are called a branched intermediate.
e) The enzymes required for strand invasion belong to a class of proteins called recombinases.
35. Consider the Holliday structure below.
Site #1
Site
A cut at Site #1 would result in two double-stranded products after recombination. Which of the following could represent the composition on each strand of one of the double-stranded products?
a) ABC and A bC
b) ABC and abc
c) a B c and abc
d) A B c and A bc
e) a B C and Abc
36. When the replication machinery encounters a single-strand break, the replication fork collapses resulting in a double-strand break. Which of the following would be the FOURTH step in repairing this damage?
a) The 3' single-strand overhang invades the intact portion of the chromosome, pairs with its complementary strand, and displaces the other.
b) Once the strand invasion is complete, branched migration occurs.
c) The broken ends are processed, with the 5' ending strand selectively degraded to create 3' overhangs.
d) Branch migration creates Holliday intermediates that are resolved by the enzyme resolvase.
e) Resol ution of the Holliday intermediate is followed by ligation and replication is restarted.
Explanation / Answer
32. During repair of DSB, the use of 3' ends for the invasion steps has the important consequence that these ends can act as primer synthesis for new DNA strand synthesis.
Hence, option “d” is correct.
33. Aneuploidy is the condition when cell has abnormal number of chromosomes and this is due to nondisjunction of homologous chromosomes.
Hence, option “a” is correct.
34. NOT true of repairing double-strand breaks by recombination is The broken ends are processed, with the 3-ending strand selectively degraded to create 5' overhangs.
Hence, option b is correct.
35. In holliday model, strands rotate followed by cleavage at the crossover point.
Hence, option d is correct.
36. When the replication machinery encounters a single-strand break, the replication fork collapses resulting in a double-strand break.Branch migration creates Holliday intermediates that are resolved by the enzyme resolvase.
Hence option d is correct.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.