Chapter 8, Problem 1CONQ

Which changes in chromosome structure cause a change in the total amount of genetic material, and which do not?

Summary Introduction

To review:

The changes in a chromosomal structure that cause a change in the total amount of genetic material.

Introduction:

A chromosome is a highly-coiled and condensed DNA (deoxyribonucleic acid) structure, having protein molecules in it, which is present in the nucleus of the cell of an animal. A single piece of coiled DNA consists of many genes, other nucleotide sequences, and regulatory elements.

Explanation of Solution

The proteins involved in the packing of chromosomes are called histones. During the formation of egg or sperm cells, structural changes in the chromosome occur due to the DNA rearrangement. The changes which occur structurally are duplication, isochromosome formation, dicentric chromosome formation, translocation, and deletion.

For example, deletion refers to the process when chromosomes break and lose their genetic material. Deletions can occur in any amount and anywhere on a chromosome. One of thetype of change in chromosomal structure, in which the amount of genetic material is not affectedis called inversion. In this, a change in the direction of genetic material occurs along a chromosome.

In translocation, a piece of DNA attaches to a different part of the same chromosome or to a different chromosome. The total amount of genetic material does not change in simple and reciprocal translocation. Duplication results in the repeat of certain amount of genetic material and deficiencies result in the shortage of genetic material.

Conclusion

Therefore, it can be concluded that duplication, isochromosome formation, dicentric chromosome formation, translocation, and deletion change the amount of genetic material while the changes which do not affect the amount of genetic material are duplication and inversion.