Answer:
Errors during Replication. DNA replication is a highly accurate process, but mistakes can occasionally occur as when a DNA polymerase inserts a wrong base. Uncorrected mistakes may sometimes lead to serious consequences, such as cancer.
In mismatch repair, mistakes that happen during DNA replication are recognized, cut out and replaced. ... This mismatched base pair causes a point mutation, which you can think of as a typo in the DNA sequence of the new strand.
Explanation:
Incorrectly paired nucleotides cause deformities in the secondary structure of the final DNA molecule. During mismatch repair, enzymes recognize and fix these deformities by removing the incorrectly paired nucleotide and replacing it with the correct nucleotide.
Eukaryotes have solved the end-replication problem by locating highly repeated DNA sequence at the end, or telomeres, of each linear chromosome. In humans and other vertebrate organisms, the sequence of nucleotides in telomeres is TTAGGG, is repeated between 100 and 1000 times.