Chapter 25, Problem 17E

(a)

Summary Introduction

To describe: The makeup of the DNA in the two daughter cells following cell division, if no repair takes place.

Concept introduction: A base analogue is a chemical which has a similar structure of a either purine or a pyrimidine. Mutations occur when the bases are incorporated incorrectly. Base excision repair is one of the efficient repair systems present to repair the damaged DNA. The base-excision repair system efficiently recognizes deaminated bases such as the deamination of adenine into hypoxanthine, the deamination of guanine into xanthine, and so on.

(b)

Summary Introduction

To describe: The makeup of the DNA in the four daughter cells, following the second round of the cell division.

Concept introduction: A base analogue is a chemical which has a similar structure of either a purine or a pyrimidine. Mutations occur when the bases are incorporated incorrectly. The base-excision repair system efficiently recognizes deaminated bases such as the deamination of adenine into hypoxanthine, the deamination of guanine into xanthine, and so on. However, when the repair system fails to correct the error, it gets incorporated to the daughter strands.