Deck 23: DNA Repair, Recombination, and Rearrangement

Question 1

Which of the following mechanisms is NOT involved in the generation of antibody diversity?

A) Recombination with excision of DNA between a V gene sequence and a J sequence
B) Splicing out of RNA sequences between a J region and a C region
C) Somatic hypermutation
D) Non-homologous end joining and DNA repair
E) Transposition

Answer 1

E

Question 2

Nucleotide excision repair:

A) involves a multisubunit enzyme.
B) preferentially repairs genes that are being actively transcribed.
C) involves making nicks on either side of a DNA lesion.
D) uses helicase, polymerase and ligase to repair the DNA.
E) all of the above.

Answer 2

E

Question 3

The SOS response to DNA damage in bacteria is error-prone because:

A) it uses DNA polymerase that lacks 5' exonuclease activity.
B) it is an inducible system.
C) the polymerases used lack 3' exonuclease activity.
D) more than one polymerase can be used to repair the damage.
E) it is stimulated by ultraviolet light that causes mutations.

Answer 3

C

Question 4

Which of the following is a feature of bacterial transposition?

A) Homologous recombination
B) DNA synthesis
C) Target site duplication
D) Deletions or inversions
E) All of the above

Question 5

Homologous recombination occurs by nicking followed by strand invasion, ligation then branch migration.

Question 6

Site-specific recombination generally requires longer homologous sequences than does homologous recombination.

Question 7

The λ genome is inserted into the E. coli genome in the lysogenic pathway by the use of ________ recombination.

Question 8

Photoreactivation using DNA photolyase is responsible for direct repair of thymine dimers in all organisms.

Question 9

Bacteria cannot use homologous recombination for DNA repair as they only have a single copy of their genome.

Question 10

________ and bulky adducts on DNA can be repaired using the nucleotide excision repair process.

Question 11

Which of the following enzyme activities is NOT used in base excision repair?

A) Glycosylase
B) Apyriminidic endonuclease
C) Deoxyribose-5'-phosphatase
D) DNA polymerase
E) Helicase

Question 12

Transcription-coupled repair usually repairs the template strand.

Question 13

Gene amplification occurring as a result of specific metabolic stress will always be reversed once the stress has been removed.

Question 14

Which of the following types of DNA damage cannot be repaired by base excision repair?

A) Depurination
B) Cytosine deamination
C) Thymine dimer
D) Single-strand break
E) Base oxidation

Question 15

The dam methylase has a role in which of the following DNA repair systems?

A) Base-excision repair
B) Nucleotide excision repair
C) Non-homologous end-joining
D) Mismatch repair
E) Homologous recombination

Question 16

Strand-displacement in homologous recombination in E. coli is facilitated by:

A) the RecBCD complex.
B) ss-binding protein.
C) RecA.
D) RuvC.
E) the chi structure.

Question 17

O6-methylguanine has a high probability of base pairing with thymine to result in a post replication mutation from a GC base pair to:

A) TA.
B) AT.
C) CG.
D) GT.
E) TC.

Question 18

The only function of Uracil-DNA N-glycosylase is to remove dUMP residues in DNA that have been arisen by deamination of cytosine.

Question 19

Base excision repair starts with cleavage of the ________ between the damaged base and the deoxyribose.

Question 20

The direct DNA repair enzymes DNA photolyase and O6-alkyguanine alkytransferase are unusual in that they are ________ after one catalytic cycle.

Question 21

One mechanism that could result in gene duplication involves ________ sister-chromatid exchange.

Question 22

Retroviruses are characterized by the presence of ________ that flank the viral structural genes.

Question 23

The movement of transposable genetic elements within a genome is essentially ________.