The spontaneous loss of amino groups from adenine in DNA results in hypoxanthine, an uncommon base, opposite thymine. What combination of proteins could repair such damage?
A) nuclease, DNA polymerase, DNA ligase
B) topoisomerase, primase, DNA polymerase
C) topoisomerase, helicase, single-strand binding protein
D) DNA ligase, replication fork proteins, adenylyl cyclase
E) nuclease, topoisomerase, primase

Question

Quizplus · Accepted Answer

The loss of an amino group from adenine in DNA results in a type of DNA damage called deamination, which can lead to a change in the base-pairing properties of DNA. In this case, hypoxanthine, an uncommon base, is formed and is then paired with thymine instead of cytosine, leading to a potential mutation. Repair mechanisms for such damage require the removal of the damaged base by a nuclease, followed by filling the gap with the correct nucleotide by a DNA polymerase and finally sealing the nick by DNA ligase. Therefore, the combination of nuclease, DNA polymerase, and DNA ligase would best repair this type of damage. Options B, C, D, and E do not include the required combination of proteins for this specific type of DNA damage.

The Spontaneous Loss of Amino Groups from Adenine in DNA