Lecture 20 - Mutations II - DNA Repair Flashcards
What are intercalating agents?
L20 S10
Molecules, such as proflavin and acridine orange, that insert themselves between adjacent bases and distort DNA structure.
Base analogs are mutagenic because of which characteristic?
L20 S11
A. They produce changes in DNA polymerase that cause it to malfunction.
B. They distort the structure of DNA.
C. They are similar in structure to the normal bases and can replace them causing errors in replication.
D. They chemically modify the normal bases.
C. They are similar in structure to the normal bases and can replace them causing errors in replication.
What type of mutation is created by UV radiation?
L20 S13
Thymine dimers
What is mismatch repair?
L20 S28
Error rate from DNA replication is ~1/1 billion.
Mismatch repair identifies mismatched bases from replication and corrects for most of them
What is base excision repair?
L20 S21
Removes modified base followed by removal of backbone and replacement with original nucleotide.
What is nucleotide-excision repair?
L20 S22
Damaged DNA is recognized and a region of DNA around the damage is excised and then resynthesized to repair the damage.
By what mechanism are thymine dimers repaired?
L20 S23
Nucleotide excision repair
What are the repair mechanisms for double stranded breaks?
L20 S24
Non-homologous end joining:
- removes nucleotides from ends of DS breaks and sticks them back together
- can ligate different chromosomes back together
Homologous recombination:
-uses homologous chromosome as a template to repair DNA break
What is translesion DNA polymerase?
L20 S25
Allows DNA synthesis to skip over distortions but is typically less accurate in base pairing.
What is the Ames test?
L20 S14
Bacteria that are unable to synthesize histidine are exposed to potential mutagens which can reverse the mutation that disabled histidine synthesis.
The bacteria are then grown on plates without histidine to determine mutation rate.
