Excision repair Flashcards
Name the 2 types of excision repair
Base and nucleotide
name the 3 enzymes in Excision repair
Repair endonuclease, polymerase and ligase
DNA Repair endonuclease is what
complex that recognises and binds to and excised the damaged base or bases
DNA polymerase does what
fills the gap, using the undamaged complementary strand of DNA as a template
DNA Ligase does what
seals the break left by DNA polymerase
Base excision repair does what
pathways remove abnormal chemically modified bases
Nucleotide excision repair does what
pathways remove larger defects, such as thymine dimers
Base excision repair is initiated by what enzyme
DNA Glycosylases
Explain what happens first in base repair
-Glycosylase binds to the modified base and cleaves the glycosidic bond between the abnormal base and pair.
What is an AP site
A site on the DNA that is missing a base
What happens at the AP site involving the AP endonuclease (Base)
The sugar phosphate backbone is removed by the AP endonuclease and phosphodiesterase
What remains after AP endonuclease and phosphodiesterase has been used (Base)
Missing nucelotide
DNA polymerase then does what and leaves what (Base)
replaces the missing nucleotide but a single strand break still remains
What seals the single strand break (Base)
DNA ligase seals the nick
Nucleotide Excision repair - ‘excinuclease’ activity requires the products of what genes
uvrA
uvrB
uvrC
