Chapter 13, Problem 5STP

Summary Introduction

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. Chromosomes are the structures that contain the genetic material that is passed from generation to generation of cells.

Answer to Problem 5STP

Correct answer:

The correct answer is option C. DNA, nucleosomes, chromatin, chromosomes

Explanation of Solution

Explanation/justification for the correct answer:

Option C. DNA, nucleosomes, chromatin, chromosomes−In order to fit into the nucleus of a cell, the DNA tightly coils around beadlike proteins called histones. The phosphate groups in DNA create a negative charge which attracts DNA to the positively charged histone proteins to form a nucleosome. The nucleosomes then group together to form chromatin fibers.Chromatin is the relaxed form of DNA in the nucleus of a cell.Chromatin fibers supercoil to make up the DNA structures known as chromosomes.Therefore, DNA is condensed into nucleosomes which are grouped into chromatin which further makes up the chromosome.

Hence this is the correct option.

Explanation for incorrect answer:

Option A. chromatin, chromosomes, DNA, nucleosomes− DNA is condensed into nucleosomes which are grouped into chromatin which further makes up the chromosome. Chromatin is not the smallest part.

Hence this is not the correct option.

Option B. chromosomes, DNA, chromatin, nucleosomes - DNA is condensed into nucleosomes which are grouped into chromatin which further makes up the chromosome. DNA is smallest and chromosome is the largest part.

Hence this is not the correct option.

Option D. nucleosomes, DNA, chromatin, chromosomes− DNA is condensed into nucleosomes which are grouped into chromatin which further makes up the chromosome. Nucleosomes is not the smallest part.

Hence this is not the correct option.