Chapter 7, Problem 1PL

Which of the following is not part of interphase?

1. cytokinesis
2. first gap phase
3. second gap phase
4. synthesis phase

Summary Introduction

Introduction:

A cell spends most of its time in the interphase of the cell cycle. At the time of interphase, a cell copies its DNA to prepare for mitosis or meiosis. The cell organelles get double in number, and the process of protein synthesis occurs during interphase.The DNA is in uncoiled chromatin form in this stage. The interphase includes the first gap phase, the second gap phase, and the synthesis phase.

Answer to Problem 1PL

Correct answer:

The correct answer is option (a) cytokinesis.

Explanation of Solution

Explanation/justification for the correct answer:

Option (a) cytokinesis. The cytoplasm of a eukaryotic cell divides to form two daughter cells at the time of cytokinesis. The cytokinesis occurs during or after the nuclear division in meiosis and mitosis. The spindle apparatus separates and transports the replicated chromatids in the cytoplasm of dividing daughter cells. Cytokinesis is not a part of interphase. So, the correct answer is option (a).

Explanation for incorrect answer:

Option (b) first gap phase. The First gap phase is also known as Gap 1 phase. The cell synthesizes the protein and grows to double from its original size in this phase. At the first gap phase, the volume of cytoplasm rise, and organelles get replicated. The first gap phase is the first stage of interphase. So, this is an incorrect answer.

Option (c) second gap phase. The second gap phase is also called the Gap 2 phase. It is the third stage of interphase. The mitochondria start to divides, and the cell continues to grow until the process of mitosis begins in the second gap phase. The chloroplast of plants divides during the second gap phase. So, this is an incorrect answer.

Option (d) synthesis phase. The synthesis phase is part of interphase, where the synthesis of DNA occurs. The synthesis phase started when the cell cleared checkpoints of the first gap phase. The synthesis phase aims to replicate DNA, so that daughter cells get complete sets of chromosomes. So option (d) is incorrect.