Recombination and Repair pt. 2 - Repair

what can cause DNA damage?

exposure to high energy light rays, mutagens, replication errors

what is direct reversal as a type of DNA repair?

base pair is damaged and is reverted back to original

what is base excision as a type of DNA repair?

removes incorrect nitrogenous base, to eventually be fixed w right base

what is nucleotide excision as a type of DNA repair?

removes up to 10bp around damaged bp to be fixed by polymerase

what is mismatch as a type of DNA repair?

removes up to 1000bp to fix mismatch

what is recombination as a type of DNA repair?

uses other sequences to fix errors

what is nonhomologous end-joining as a type of DNA repair?

pastes two blunt ends together

what is error prone repair?

last resort repair system - random bases are added if the information is gone, and allows for errors to be present to fix damaged DNA

what is the process of base excision repair?

glycosylase recognizes an incorrect base in DNA, flips it up, and removes it. lyases remove the sugar-phosphate backbone to create an empty nucleotide space for polymerase to fill and ligase to connect

what is the process of nucleotide excision repair?

small region upstream and downstream is removed by exonuclease (made up of UvrA, UvrB, and UvrC), and polymerase rebuilds it using the bottom of the template before being connected w phosphodiester backbone by ligase

what are the three mismatch repair types?

errors in replication, oxidative damage, insertion due to DNA polymerase slipping on polynucleotide track

what is the process of fixing errors in replication as a type of mismatch repair?

kink in DNA is formed through mismatch, mutS and mutL bind, mutS and mutH join on either side, the daughter strand is removed as the system looks for methylation patterns (around 1000bp), then polymerase resynthesizes

what is the process of fixing oxidative damage as a type of mismatch repair?

if a nucleotide isnt recognized as being incorporated to DNA, MutT will attach and try to get rid of it. its either immideately recognized and fixed or replication occurs anway. MutY recognizes, removes and replaces the nucleotide

what is the process of fixing an insertion due to polymerase slippage as a type of mismatch repair?

MutS and MutL will bind to the inserted loop from DNA polymerase slipping, the MutSL system will remove the loop with endonucleases and helicases, and DNA polymerase will fill in the missing bases