Question

Any incorrectly paired nucleotides remaining after replication produce a deformity in the secondary structure of the DNA. That deformity is recognized by enzymes that excise the incorrectly paired nucleotide and use the original nucleotide strand as a template to replace the incorrect nucleotide. (pg 246)

Answer 1

Mismatch repair enzymes recognize and fix incorrectly paired nucleotides during DNA replication by excising the incorrect nucleotide and replacing it with the correct one using the original nucleotide strand as a template.

Step-by-step explanation:

During DNA replication, errors can occur and result in incorrectly paired nucleotides. These errors can lead to deformities in the secondary structure of the DNA. However, there are repair mechanisms in place to fix these errors. Mismatch repair enzymes recognize the incorrectly paired nucleotide and excise it, using the original nucleotide strand as a template to replace the incorrect nucleotide with the correct one.

Nucleotide excision repair is another type of repair mechanism where enzymes remove incorrectly paired bases by making cuts on both the 3' and 5' ends of the incorrect bases. This repair is especially relevant for damage like thymine dimers caused by UV radiation, where the damaged nucleotides are removed and replaced with correct bases to maintain DNA integrity.