A) assuming that no DNA is repaired, describe the makeup of the DNA in the two d

Question

A) assuming that no DNA is repaired, describe the makeup of the DNA in the two daughter cells 3. Removal of an amino group -NH2) from an adenosine residue (A) produces an inosine residue d) Inosine forms hydrogen bonds with cytidine (C). Imagine that an A residue in DNA loses its amino group, but the cell does not repair the damaged DNA, and then the cell enters S phase of the cell cycle. In this diagram, N represents any nucleotide in the double-stranded DNA. (Hint: start with a diagram, and remember that DNA replication occurs before mitosis.)

Explanation / Answer

Answer A)

Assuming that no DNA is repaired and the same fragment undergoes replication, we would consider that the repair machinery of the DNA is not working in order to repair it. Adenosine here, is getting deaminated and is resulting in the formation of inosine, which would base pair with cytosine. This is referred to as a pre mutagenic event . This would continue towards a transition mutation, since the The DNA would not be repaired . In the resulting daughter cells, the Inosine will be paired to Cytosine as that is the most stable pairing; though inosine can pair to other bases as well.

Answer B)

The make up of the DNA in the subsequent four daughter cells would be similar, consisting of a transition mutation, which would continue to grow and the same mutated DNA would be incorporated in the subsequent generations. The effect on the phenotype cannot be predicted as of now , as there are certain mutations, that do not even show a major change in the phenotype of the person.

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