Mismatch repair

Definition

Mismatch repair is a cellular process that corrects errors that occur during DNA replication, specifically the misincorporation of nucleotides. This mechanism ensures the fidelity of genetic information by identifying and repairing these mismatched pairs, thus preventing potential mutations that could arise if left unchecked. It plays a critical role in maintaining genomic stability and preventing diseases linked to DNA errors.

5 Must Know Facts For Your Next Test

1. Mismatch repair primarily involves recognizing and excising the incorrectly paired nucleotide from the newly synthesized strand.
2. Key proteins involved in mismatch repair include MutS, which detects mismatches, and MutL, which facilitates the repair process.
3. This repair mechanism is particularly important in organisms with high fidelity DNA replication systems, such as eukaryotes.
4. Defects in mismatch repair pathways can lead to increased rates of mutation and are associated with certain cancers, such as Lynch syndrome.
5. The process relies on the ability to distinguish between the newly synthesized strand and the original template strand, typically using methylation patterns.

Review Questions

• How does mismatch repair contribute to genomic stability?
  • Mismatch repair contributes to genomic stability by identifying and correcting errors made during DNA replication. If these errors are not corrected, they can lead to permanent mutations that may compromise the integrity of the genome. By repairing mismatched base pairs, this mechanism helps ensure that genetic information is accurately passed on during cell division, thereby preventing potential diseases and maintaining overall cellular health.
• Discuss the role of key proteins in the mismatch repair mechanism and their specific functions.
  • Key proteins in the mismatch repair mechanism include MutS and MutL. MutS functions as a sensor that recognizes mismatched base pairs in the DNA. Once a mismatch is detected, MutL is recruited to facilitate the repair process by coordinating the excision of the incorrect nucleotide and the subsequent synthesis of the correct one. This collaboration ensures that mismatches are efficiently corrected to maintain genomic integrity.
• Evaluate the implications of defective mismatch repair systems on human health and disease risk.
  • Defective mismatch repair systems can significantly impact human health by increasing the likelihood of mutations, which can lead to various diseases, most notably certain types of cancer like Lynch syndrome. Individuals with mutations in mismatch repair genes have a higher predisposition to develop colorectal cancer and other malignancies due to the accumulation of genetic errors. Understanding these implications highlights the critical role of DNA repair mechanisms in cancer prevention and informs potential therapeutic approaches for at-risk populations.

Related terms

DNA Polymerase: An enzyme responsible for synthesizing new strands of DNA during replication, ensuring accurate base pairing.

Nucleotide Excision Repair: A DNA repair mechanism that removes and replaces damaged DNA segments, which may result from environmental factors like UV radiation.

Mutagenesis: The process by which genetic information is changed, resulting in mutations, which can occur due to errors during DNA replication or external factors.