Question

6-48 In somatic cells, if a base is mismatched in one new daughter strand during DNA replication, and is not repaired, what fraction of the DNA duplexes will have a permanent change in the DNA sequence after the second round of DNA replication

Answer 1

Answer:

1/4

Explanation:

DNA replication is semi-conservative, which means that during this process one DNA strand will be from the original DNA template, whereas the other DNA strand will be newly synthesized. In the first round of DNA replication, daughter cells receive a DNA molecule containing one original DNA strand and one newly-synthesized DNA strand (in this case, one of these daughter cells will contain a mismatch). If the mismatch is not repaired, then in the second round of replication the DNA molecule containing the mismatch would separate during replication, and the DNA strand containing the erroneous nucleotide will serve as a template for the synthesis of a new DNA molecule, thereby producing a permanent mutation.