DNA Repair Mechanisms

Vocabulary flashcards covering key terms related to cellular DNA repair pathways, their enzymes, and types of damage addressed.

DNA Damage

Alterations in DNA arising from internal metabolic processes or environmental factors such as radiation that can lead to harmful mutations.

DNA Repair

Collective term for the three built-in cellular mechanisms that correct DNA damage and maintain genome integrity.

Direct Reversal

A repair mechanism that directly reverses UV-induced pyrimidine dimers; carried out by photolyase in many bacteria and fungi but not in humans.

Photolyase

The enzyme that absorbs light energy to split fused pyrimidine bases during direct reversal repair.

Excision Repair

General strategy in which the undamaged strand guides removal of lesions and DNA polymerase fills in the correct sequence.

Base Excision Repair (BER)

Type of excision repair that removes a single damaged base and allows DNA polymerase to insert the correct nucleotide.

Nucleotide Excision Repair (NER)

Excision repair pathway that removes bulky, multi-base lesions through damage recognition, excision of a DNA segment, and resynthesis; present in almost all organisms.

Post-Replication Repair

Repair processes that act after DNA synthesis to fill gaps left behind during replication.

Recombinational Repair

A form of post-replication repair that uses the undamaged sister chromatid as a template to fill replication gaps.

Error-Prone Repair

Post-replication pathway in which the damaged strand itself serves as a template, often introducing mutations.

Okazaki Fragment Gap

Unreplicated region left on the lagging strand during synthesis that can trigger post-replication repair pathways.

Pyrimidine Dimer

Covalent fusion of adjacent pyrimidine bases (usually thymine) caused by UV light, leading to DNA distortion that requires repair.