Chapter 10, Problem 14STP

Summary Introduction

To describe:

The manner in whichchromosome change during the S phase.

Introduction:

Cells reproduce by a cycle of growing and dividing called the cell cycle. There are three main stages of a cell cycle; interphase, mitosis and cytokinesis.A cell spends most of the time in interphase. It is the stage in which a cell grows, carries out cellular activities and replicates. It makes copies of DNA to enter the next stage of the cycle. During interphase a cell does not divide but prepares itself for cell division. There are three stages in interphase; G₁, S and G₂.

Answer to Problem 14STP

In S stage of interphase DNA is replicated resulting in doubling of DNA.

Explanation of Solution

The interphase is divided into three stages; G₁, S and G₂. The S phase or the synthesis phase marks the period during which synthesis of DNA takes place. In this phase the amount of DNA per cell doubles. However there is no increase in chromosome number. A diploid cell will have diploid number of chromosomes. Only replication of DNA occurs to prepare the cell for cell division. The chromosomes appear in the form of chromatin which is the relaxed form of DNA.