Chapter 18, Problem 1TY

Which of the following is an example of an epigenetic change that alters gene expression?

1. a. chromatin remodeling
2. b. covalent histone modification
3. c. localization of histone variants
4. d. DNA methylation
5. e. all of the above

Summary Introduction

Introduction:

Epigenetics refers to the study of changes in the expression of genes. The epigenetic changes do not change the sequence of DNA. The epigenetic changes are natural changes and they can also occur due to factors like age, lifestyle, or health conditions.

Answer to Problem 1TY

Correct answer:

The examples of epigenetic change that alter the gene expression are chromatin remodeling, covalent histone modification, localization of histone variants, and DNA methylation. Hence, the correct answer is option e.

Explanation of Solution

Reason for correct answer:

Chromatin remodeling is the modification in the structure of chromatin. Thereby, genomic DNA enters into transcription machinery proteins and alters gene expression. The covalent histone modification modifies histone proteins. The localization of histone variants brings about epigenetic changes. DNA methylation process alters the gene expression but does not disturb the DNA sequence. So, all these are the examples of epigenetic change which alter the gene expression.

Option e is given as “all of the above”.

Hence, the correct answer is option e.

Reasons for the incorrect answer:

Option a is given as, “chromatin remodeling”

Chromatin remodeling refers to the modification done to the structure of chromatin. Thereby, permitting the entry of genomic DNA into the transcription machinery proteins which will result in the alteration of gene expression. However, covalent histone modification, DNA methylation, and the localization of histone variants are also examples of epigenetic change. Hence, option a is incorrect.

Option b is given as, “covalent histone modification”.

The covalent histone modification alters the histone proteins. These modifications to the histone proteins are responsible for the gene expression. However, chromatin remodeling, DNA methylation, and the localization of histone variants are also examples of epigenetic change. Hence, option b is incorrect.

Option c is given as, “localization of histone variants”.

Histone variants cause differentiation of the chromatin. This differentiation of chromatin brings about genetic changes. However, chromatin remodeling, DNA methylation, and covalent histone modification are also examples of epigenetic change. Hence, option c is incorrect.

Option d is given as, “DNA methylation”.

DNA methylation is the addition of methyl groups to the molecule of DNA, but it does not alter the sequence of DNA. So, it is an example of epigenetic change along with chromatin remodeling, covalent histone modification, and the localization of histone variants are also examples of epigenetic change. Hence, option d is incorrect.

Hence, the options a, b, c, and d are incorrect.

Conclusion

Thus, chromatin remodeling, DNA methylation, covalent histone modification, and the localization of histone variants are all examples of epigenetic change that alters the expression of the gene.