Chapter 11, Problem 19STP

Summary Introduction

To describe:

The function of microtubules and predict what might happen if cells did not have microtubules

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 19STP

During prophase stage of mitosis, spindle apparatus which consists of spindle fibers, centrioles and aster fibers appear in the animal cells. Al these structures are made of microtubules.

The spindle apparatus helps in moving and organizing the chromosomes before cell division.

Explanation of Solution

During prophase microtubule structures called spindle fibers form in the cytoplasm. The centrioles are a pair of microtubule structures produced in animals and in some protist cells. They migrate to the poles of the cells and produce another set of microtubules called aster fibers which have a star like appearance. The whole structure including the spindle fibers, centrioles and aster fibers is called spindle apparatus.

Spindle apparatus is very important in animal cells during cell division. It helps in aligning the chromosomes along the equator so that the new cells receive one complete copy of the DNA.