Chapter 26 - DNA Repair Flashcards
Direct Repair
Direct repair of damaged bases. (Photoactivation, O6-alkylguanine transferase)
Photoreactivating enzyme (DNA Photolyase)
Repairs cyclobutane (thymine dimers)
What enzyme is responsible for fixing alkylated guanine residues?
O6 Alkylguanine transferase
Nucleotide Excision Repair
Removes segment of damaged nucleotides, replaces it with new strand.
uvr A, uvr B, uvr C, helicase II (uvr D), DNA pol I, DNA ligase
- transcription coupled repair
Base Excision Repair
Removes BASES of damaged nucleotides, replaces the damaged nucleotides with new strand.
Uracil Replacement: Uracil-DNA-N-Glycolyase, Apyrimidinic Endonuclease, DNA pol I, DNA ligase
Oxidative repair: MutM, MutY, MutT
Mismatch Repair
MutS, MutH (methylation dependent), MutL, Exonuclease, Helicase II (MutU), DNA pol III, DNA ligase
Homologous recombination
- Requires DNA homology
- Holliday junction, single nick (Meselson)
- RecA, Rec BCD (3’ degradation)
Sequence Specific Recombination
Recombination at specific sequences, directed by specific DNA-protein interactions.
Transposons
Transposable genetic elements, genes that can move from place to place
Transposons
Transposable genetic elements, genes that can move from place to place
Error-prone Repair
dinB —> DNA pol IV
umuC, umuD –> DNA pol V
Daughter-strand repair
Doesn’t repair damage, but allows replication to continue.
RecA, F, O, R
Ruv A, B, C
DNA polymerase, DNA lygase
What kinds of pyrimidine-pyrimidine dimers/photoproducts are there?
(1) Thymine dimers
(2) 6-4 photoproduct
What kinds of pyrimidine-pyrimidine dimers/photoproducts are there?
(1) Thymine dimers
(2) 6-4 photoproduct
O6-methylguanine binds to ___?
Thymine
