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How do cells repair breaks in DNA strands?
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Primates are among the longest-lived groups of mammals.
Cells maintain the integrity of their genetic code through various enzymatic repair mechanisms that address DNA strand breaks and other lesions. Because DNA damage can corrupt genetic messages and lead to cell malfunction or death, the efficiency of these repair systems is a critical factor in the aging process.123
When individual strands of DNA break, cells typically employ an enzymatic mechanism that identifies and destroys the damaged region. The cell then resynthesizes the excised portion by using the corresponding segment of the complementary strand as a template, ensuring the accuracy of the repair.31
Other repair pathways include:
- Excision Repair: Enzymes detect structural distortions in the DNA, nick the strand on either side of the lesion, and excise the damaged segment. DNA polymerase and DNA ligase then fill and seal the resulting gap.12
- Recombination Repair: If a chromosome is severely damaged, the cell may use the sequence from an undamaged sister chromosome to provide a correct template for repair.42
- Direct Reversal: Specific enzymes, such as DNA photolyase, can directly reverse certain types of damage, such as pyrimidine dimers caused by UV light.2