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CHAPTER 23

Terms in this set (18)

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.
B
T/F The only function of Uracil-DNA N-glycosylase is to remove dUMP residues in DNA that have been arisen by deamination of cytosine.
FALSE
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
C
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.
E
T/F Photoreactivation using DNA photolyase is responsible for direct repair of thymine dimers in all organisms.
FALSE
________ and bulky adducts on DNA can be repaired using the nucleotide excision repair process.
Thymine dimers
The direct DNA repair enzymes DNA photolyase and O6-alkyguanine alkytransferase are unusual in that they are ________ after one catalytic cycle.
inactivated
Base excision repair starts with cleavage of the ________ between the damaged base and the deoxyribose.
Answer:glycosidic BOND
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
E
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.
C
T/F Transcription-coupled repair usually repairs the template strand.
TRUE
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
D
Strand-displacement in homologous recombination in E. coliis facilitated by:
A) the RecBCD complex.
B) ss-binding protein.
C) RecA.
D) RuvC.
E) the chistructure.
C
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
E
T/F Bacteria cannot use homologous recombination for DNA repair as they only have a single copy of their genome.
FALSE
T/F Site-specific recombination generally requires longer homologous sequences than does homologous recombination.
FALSE
T/F Homologous recombination occurs by nicking followed by strand invasion, ligation then branch migration.
TRUE
The λ genome is inserted into the E. coligenome in the lysogenic pathway by the use of ________ recombination.
site-specific
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