Fundamentals of Molecular Biology - V.I. Rezyapkin 2009

DNA Repair
Repair of DNA Replication Errors

Although DNA polymerase possesses proofreading activity, Replication is not entirely error-free. During METABOLISM/36.html">DNA replication, base-pairing errors occur, resulting in the incorporation of NUCLEOTIDES into the daughter DNA strand that are not complementary to those of the parent strand. Because these errors arise on the daughter strand, the Mismatch Repair system must replace the non-complementary bases exclusively on this strand. To distinguish between the parent and daughter DNA strands, the repair system relies on structural differences between them. In the parent DNA strand, certain adenine nitrogenous bases are methylated, whereas in the newly synthesized daughter strand they are not yet methylated immediately following replication. Only after a certain period of time following replication do methylases attach methyl groups to adenines within GATC sequences. While these strands remain unmethylated, the repair system identifies the daughter strand and corrects the errors (Fig. 3.8).

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Fig. 3.8. Repair of DNA replication errors



Last update: 12/08/2026

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