Chapter 5, Problem 1CONQ

Define the term epigenetic inheritance, and describe two examples.  

Summary Introduction

To review:

Epigenetic inheritance and its two examples.

Introduction:

Non-mendelian inheritance refers to inheritance of genes which does not follow one or more laws of inheritance given by Gregor Johan Mendel. The maternal effect, epigenetic inheritance, and extra-nuclear inheritance are examples of non-mendelian inheritance.

Explanation of Solution

The analysis of alteration in the chromosome or a gene resulting in the changes in the expression of a gene is known as epigenetic inheritance. These changes do not necessarily pass to future generations. These changes result in alteration of the phenotype of the individual for the entire lifetime but when this individual make gametes, it would contain the chromosome without any alterations.

The two examples are described as follows:

1. X-chromosome inactivation: It refers to the phenomenon that occurs in some female individual mammals. In order to maintain the level of gene products, one of the X-chromosome is made inactive. The expression of the genes present on one of the chromosomes is silenced by packaging it into a structure whose promoter is inaccessible by RNA polymerase.

2. Genomic Imprinting: It is an epigenetic inheritance in which marking is made on a stretch of DNA (deoxyribonucleic acid). The mark made is contained in the individual and is sighted through the entire life of an individual that has inherited such DNA. The gene expressed could belong to the mother or father depending on whether the alteration occurred during oogenesis or spermatogenesis. A bird able to differentiate between its own parents and other birds is an example of genomic imprinting.

Conclusion

Therefore, it can be concluded that epigenetic inheritance involves the changes in the chromosomal genes or chromosome resulting in the phenotypic changes. X-chromosome inactivation and genomic imprinting are examples of epigenetic inheritance.