Library · Cellular process
How DNA Repairs Its Own Damage
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DNA is the molecule where each cell's information is written, and it is neither static nor protected: every day it takes billions of hits. If repair were not running all the time, the genome, which is the complete text, would lose its integrity.
DNA has two strands facing each other, and every letter on one corresponds to a letter on the other. When damage affects a single strand, the cell has several ways to fix it, among them mismatch repair, which catches wrongly paired letters, and base and nucleotide excision repair.
They all work on the same principle: they copy from the opposite strand, the way you would piece a torn page back together by looking at the page next to it. That is why a break in both strands at once is far harder to fix: at that point there is nothing left to copy from.
And when the genes that carry out that repair are mutated, cancer can appear. MLH1 and MSH2 are two of the genes involved in Lynch syndrome, and BRCA1 and BRCA2 are two of those involved in breast cancer.
In brief
DNA takes billions of hits every day; without constant repair the genome would lose its integrity.
Several pathways handle single-strand damage, among them mismatch repair and base and nucleotide excision repair.
Repair copies from the complementary strand; a double-strand break is harder because that template is missing.
Corrected by copying from the facing page.
Mutations in the repair genes can lead to cancer: MLH1 and MSH2 in Lynch syndrome, BRCA1 and BRCA2 in breast cancer.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingBiochemistry, DNA Repair, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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