What is mismatch repair in DNA replication?
DNA mismatch repair (MMR) is a system for recognizing and repairing erroneous insertion, deletion, and mis-incorporation of bases that can arise during DNA replication and recombination, as well as repairing some forms of DNA damage.
What are 3 ways mistakes in DNA are repaired during replication?
Once the incorrect nucleotide has been removed, it can be replaced by the correct one.
- Proofreading by DNA polymerase corrects errors during replication.
- In mismatch repair, the incorrectly added base is detected after replication.
- Nucleotide excision repairs thymine dimers.
What fixes mismatch repair?
Mismatch repair
- A mismatch is detected in newly synthesized DNA.
- The new DNA strand is cut, and a patch of DNA containing the mispaired nucleotide and its neighbors is removed.
- The missing patch is replaced with correct nucleotides by a DNA polymerase.
- A DNA ligase seals the remaining gap in the DNA backbone.
What is mismatch repair proficient?
If one or more proteins are not expressed or are dysfunctional, the status is called dMMR; otherwise, the status is considered mismatch repair proficient (pMMR). MLH1 and MSH2 play pivotal roles in the process of MMR by dimerizing and interacting with MSH6 and PMS2.
What happens during mismatch repair?
Mismatch repair happens right after new DNA has been made, and its job is to remove and replace mis-paired bases (ones that were not fixed during proofreading). Mismatch repair can also detect and correct small insertions and deletions that happen when the polymerases “slips,” losing its footing on the template 2.
Why are methyl CH3 groups important in mismatch repair?
Why are methyl (CH3) groups important in mismatch repair? They mark the parental strand of DNA.
What happens when DNA repair goes wrong?
Incorrectly paired nucleotides that still remain following mismatch repair become permanent mutations after the next cell division. This is because once such mistakes are established, the cell no longer recognizes them as errors.
What is a base mismatch?
Base pair mismatches that arise occasionally during replication are subsequently repaired in a process that takes advantage of the fact that newly synthesized DNA in some organisms is undermethylated. From: Encyclopedia of Genetics, 2001.