Recombination

Question 1

In mitosis, homologous double strand break repair preferentially utilizes the _______ chromatid as repair template and exhibits a bias toward _____ recombination.

Answer 1

sister, noncrossover

Question 2

in meiosis, homologous recombination preferentially utilizes the _____ chromatid as repair template and generates _____ recombinants.

Answer 2

homologous, both crossover and noncrossover

Question 3

In the Holliday model of genetic recombination:

Answer 3

regions of heteroduplex DNA are generated by branch migration of Holliday junctions

Question 4

Recombination is initiated by a double strand break on one of the participating chromatids in what model?

Answer 4

DSBR model of genetic recombination

Question 5

The broken ends are extensively resected to create lengthy single strand regions in what model?

Answer 5

DSBR

Question 6

following transfer of 3’ ends to form D loops, synthesis of new DNA from the 3’ ends is required to repair the gaps in what model?

Answer 6

DSBR

Question 7

regions of heteroduplex DNA are generated by branch migration of Holliday junctions in what model?

Answer 7

DSBR

Question 8

resolution of double Holliday junctions is biased so that only crossover products are generated in what model?

Answer 8

DSBR

Question 9

enzyme that has both DNA helicase activity and single-strand endonuclease activity

Answer 9

RecBCD enzyme

Question 10

A linear duplex molecule and a single strand circular molecule that is identical to one of the strands of the duplex can or cannot be paired with RecA?

Answer 10

can

Question 11

a circular duplex molecule and a linear single strand molecule that is identical to one of the strands of the duplex can or cannot be paired by RecA?

Answer 11

can

Question 12

Two identical circular duplex molecules, one of which contains a short gap in one strand can or cannot be paired by RecA?

Answer 12

can

Question 13

Two identical circular duplex molecules, one of which contains a nick in one strand can or cannot be paired by RecA?

Answer 13

cannot

Question 14

A full-length duplex chromosome ( could be millions of base pairs) and a 20 base single strand oligonucleotide that matches a 20 base stretch of one strand of the chromosome can or cannot be paired by RecA?

Answer 14

can

Question 15

What kind of filaments are about 1.5 times as long as naked DNA, require single-strand DNA to initiate, are helicases consisting of about six ___ monomers per helical turn, contain binding sites for two DNA molecules?

Answer 15

RecA filaments

Question 16

Holliday junctions are recognized and bound by:

Answer 16

RuvC and RuvA

Question 17

Holliday junctions are generated by the enzymatic activity of:

Answer 17

RecA

Question 18

Holliday junctions are cleaved by the enzymatic activity of:

Answer 18

RuvC

Question 19

What is the doughnut shaped hexamer with ATPase activity which can rotate a DNA duplex and pull it through its central pore?

Answer 19

RuvB

Question 20

In meiotic recombination, the enzyme responsible for inducing double strand breaks.

Answer 20

Spo11

Question 21

In meiotic recombination, the enzyme responsible for resecting double strand breaks and generating long single-strand ends.

Answer 21

MRX

Question 22

In meiotic recombination, the enzymes responsible for pairing and strand transfer are:

Answer 22

DMC1 and Rad51

Question 23

What enzymes are involved in the meiotic SDSA pathway?

Answer 23

MRX, DMC1, Rad51, Spo11

Question 24

SDSA pathway is thought to be important for generating non-crossover recombinants in:

Answer 24

mitosis and meiosis

Question 25

What happens when DNA polymerases encounter a nick in the template strand?

Answer 25

DNA replication pauses adjacent to the nick, creating a DSB. Recombination enzymes such as Rad51 are recruited and DSBR restores the replication fork.

Question 26

True or false: In meiotic recombination, gene conversion can result either from mismatch repair of heteroduplexes, or from extension of 3’ ends after D-loop formation

Answer 26

True

Question 27

True/False: The SDSA pathway yields gene conversions but not crossovers whereas the DSBR pathway yields both gene conversions and crossovers

Answer 27

True

Question 28

True/ False: In DSBR pathway, one of the two participating chromatids is unaltered by the recombination event, whereas in the SDSA pathway, in general, both participating chromatids are altered by the recombination event.

Answer 28

False

Question 29

In gene conversion, a pair of alleles segregates at an unequal ratio, such as 3:1, 1:3, 5:3, or 3:5

Answer 29

True

Question 30

Non-mendelian segregation of alleles is a hallmark of genetic recombination

Answer 30

True