MMR in DNA refers to Mismatch Repair, a crucial single-strand repair system.
Mismatch Repair Explained
Mismatch repair (MMR) is essential for maintaining the integrity of our DNA. It acts as a quality control mechanism, identifying and correcting errors that occur during DNA replication. These errors can include:
- Base mismatches: Incorrect pairing of DNA bases (e.g., guanine paired with adenine instead of cytosine).
- Insertion/Deletion Loops (IDLs): Loops formed due to insertions or deletions of nucleotides.
How MMR Works
MMR systems work by:
- Recognition: Identifying mismatches or loops in the newly synthesized DNA strand.
- Excision: Removing the section of DNA containing the error.
- Synthesis: Filling the gap with the correct sequence, using the complementary strand as a template.
Importance of MMR
A functional MMR system is vital because:
- It corrects errors that DNA polymerase misses during replication.
- It reduces the mutation rate, preventing accumulation of harmful changes in DNA.
- Defects in MMR are linked to increased cancer risk, as mutations can lead to uncontrolled cell growth.
