Chapter 9, Problem 12A

Summary Introduction

To criticize:

The statement “Interphase is the resting period”for the cell before it begins mitosis.

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. Different activities occur in each phase of cell cycle.

Answer to Problem 12A

Interphase is the first and longest stage in cell cycle. It is not a resting stage as the cell is very active in this stage. The cell grows, performs all cellular activities and undergoes DNA replication. It prepares itself for the next stage of the cell cycle that is mitosis. Hence it would be inaccurate to call interphase the “resting period of cell cycle”.

Explanation of Solution

A cell spends almost 90 percent of its time in interphase. It is the stage in which a cell grows, develops into a mature, functioning cell, duplicates its DNA and prepares for nuclear division. It makes copies of DNA to enter the mitosis stage of the cycle. During interphase a cell does not divide but prepares itself for cell division. There are three sub- stages in interphase; G₁, S and G₂. In G₁ stage, cell grows, carries out regular cell functions and prepares for synthesis of DNA. In S stage DNA is replicated and in G₂ stage cell prepares for cell division. So, many activities take place in interphase. So, the cell is not resting in this stage.