Topic 8b - DNA Repair Mechanisms and Mutations

Question 1

A mutation resulting from exposure to a mutagen from outside the cell.

Answer 1

Induced Mutation

Question 2

Chemicals that can be incorporated into the DNA instead of a base, usually resulting in substitution.

Answer 2

Base Analogs

Question 3

Modifies an existing base by adding a methyl or ethyl group that changes the pairing, usually resulting in substitution.

Answer 3

Alkylating Agent

Question 4

Mimics spontaneous deamination and similarly causes a substitution.

Answer 4

Deaminating Agent

Question 5

Modifies an existing base and results in a substitution.

Answer 5

Oxidative Reaction

Question 6

A mutagen that binds to bases and distorts the double helix.

Answer 6

Intercalating Agent

Question 7

Creates an extra bond between adjacent thymine nucleotides on the same strand, resulting in a thymine dimer.

Answer 7

UV Light Mutation

Question 8

Causes base oxidation and strand breakage on one or both of the strands.

Answer 8

Ionizing Radiation

Question 9

When a base is modified due to exposure, resulting in mis-pairs.

Answer 9

Base Oxidation

Question 10

Acts to immediately correct substitution mutations.

Answer 10

Mismatch Repair

Question 11

Finds chemical modifications of the old strand that have not been applied to the new strand and removes the error region allowing transcriptional polymerase to fill the gap.

Answer 11

Mismatch Repair in Prokaryotes

Question 12

Finds nicks in the new strand and removes the error region allowing transcriptional polymerase to fill the gap.

Answer 12

Mismatch Repair in Eukaryotes

Question 13

Targets chemically modified nitrogenous bases to replace the nucleotide using many enzymes.

Answer 13

Base Excision Repair

Question 14

Glycosylase, AP endonuclease, DNA Polymerase I/Beta, Ligase

Answer 14

Base Excision Repair Enzymes

Question 15

A repair enzyme that removes damaged bases.

Answer 15

Glycosylase

Question 16

Removes the sugar-phosphate group.

Answer 16

AP Endonuclease

Question 17

Targets bulky damage (DNA distortions) and removes the DNA segment.

Answer 17

Nucleotide Excision Repair

Question 18

Photolyase enzymes use blue light energy to break thymine dimers, not found in placental mammals.

Answer 18

Photoreactivation/Direct Repair

Question 19

Targets double stranded breaks and uses sister chromatids or homologous chromosomes to align the broken strand with a template using enzymes involved in meiotic recombination.

Answer 19

Homologous Recombination Repair

Question 20

Targets double stranded breaks and uses molecules that manage recombination but can only be done immediately after synthesis using microhomologies.

Answer 20

Nonhomologous End-Joining

Question 21

Short sequences on the ends of DNA that share a few bases.

Answer 21

Microhomologies

Question 22

Translesional DNA polymerase is used in areas of bulky damage to replicate strands and results in a high misincorporation rate, usually only expressed due to extreme genomic damage in prokaryotes.

Answer 22

Translesion Synthesis

Question 23

gRNA positions the Cas9 enzyme to make a double stranded break at the desired location to utilize DNA repair mechanisms to silence or edit a gene.

Answer 23

CRISPR/Cas9