Chapter 9, Problem 13A

Summary Introduction

To explain:

The relationship of DNA, a chromosome and chromatin

Introduction:

DNA double helix is the fundamental unit of heredity. It is made up of a deoxyribose sugar, a phosphate and a base. They carry genetic codes to guide our body to perform various functions. These DNA molecules are packed into tightly wound structures called chromosomes which appear as beaded strings under light microscope.

Answer to Problem 13A

Chromosomes are the structures that contain the genetic material that is passed from generation to generation of cells. Chromatin is the relaxed form of DNA in the nucleus of a cell. DNA is condensed into chromatin which further makes up the chromosome.

Explanation of Solution

DNAis deoxyribonucleic acid, also known as double helix. It is the made from double stranded nucleic acids which are very long, thread like structures. They store the genetic information of the cell. During mitosis, these DNA molecules coil around proteins called histones to form chromatin. These chromatins are smaller in volume and can be easily packaged in the nucleus of the cell. The chromatins are further condensed by special proteins to form chromosomes which can be replicated and then separated during mitosis.