Difference Between Genetics and Epigenetics

Main Difference – Genetics vs Epigenetics

Genetics and epigenetics are two types of studies of genes. The main difference between genetics and epigenetics is that genetics is the study of genes that control the functions of the body whereas epigenetics is the study of inheritable changes of the organisms caused by the modification of gene expression. Genes are the basic units of heredity that pass genetic information over generations. The structure of genes and its alterations are studied in genetics. In epigenetics, the modifications of the gene expression that alter the phenotype are studied.

Key Areas Covered

1. What is Genetics
– Definition, Fields, Role
2. What is Epigenetics
– Definition, Fields, Role
3. What are the Similarities Between Genetics and Epigenetics
– Outline of Common Features
4. What is the Difference Between Genetics and Epigenetics
– Comparison of Key Differences

Key Terms: Alleles, Chromatin Structure, DNA Methylation, Epigenetics, Genetics, Heredity, Inheritance, Mutations

What is Genetics

Genetics refers to the study of heredity and the variation of inherited characteristics. Heredity is the biological process by which a parent passes its genetic information to its offspring. Every individual inherits genes from its mother and father. Hence, gene serves as the basic unit of heredity. The alternative forms of a gene are called alleles. Many organisms have two alleles that can be either homozygous or heterozygous. Some alleles are dominant over the others and determine the phenotypes of a particular organism. Many genes are made up of DNA. DNA is packaged into the nucleus by forming chromosomes. The organization of genes is shown in figure 1.

Main Difference - Genetics vs Epigenetics

Figure 1: Chromosome and Gene

Humans have 46 chromosomes: 22 autosomes and two sex chromosomes. More than 20,000 genes are located on those 46 chromosomes. The inheritance of genes was first described by Gregor Mendel in 1890s. Some genes exhibit Mendelian inheritance while others exhibit non-Mendelian inheritance. These patterns of inheritance are studied in genetics.

Some alleles cause genetic disorders. They are also studied in genetics. The alterations of the nucleotide sequence in genes and chromosomes are called mutations. The effects of mutations on a particular organism are also studied in genetics. Mutations cause the formation of new alleles. The variations of alleles cause genetic variations within a particular population. These variations are studied under population genetics.

What is Epigenetics

Epigenetics refers to the study of inheritable changes of the organisms caused by the modification of gene expression, rather than the alteration of the genetic material of the organisms. The modification of gene expression is a natural process that occurs within the cell to adjust the types and the number of proteins expressed in the cell. The two main types of such modifications are DNA methylation and histone modification. In DNA methylation, a methyl group is added to tag DNA, either activating or repressing the expression of that DNA. In histone modification, the epigenetic factors bind to the tails of histones, altering the extent of wrapped DNA around the nucleosomes. Histones are a type of proteins around which DNA can bind during the formation of chromatin. The extent of wrapping of DNA around the histones alters the gene expression. The mechanisms of epigenetics are shown in figure 2.

Difference Between Genetics and Epigenetics

Figure 2: Epigenetic Mechanisms

Two types of chromatin are formed depending on the degree of wrapping or chromosome condensation. The loosely-wrapped chromatins are euchromatin and they contain actively-expressing genes. The tightly-wrapped chromatin is heterochromatin and they contain both transcriptionally and genetically inactive genes.

Both DNA methylation and histone modification can be altered under the influence of environmental factors such as aging, diet, chemicals, drugs or various diseases. These influences and the degree of the modification of the gene expression are studied in epigenetics.

Similarities Between Genetics and Epigenetics

Genetics and epigenetics are two types of studies of genes.
The changes of the entities studied in both genetics and epigenetics are inheritable.
The entities studied in both genetics and epigenetics are involved in the control of the formation and functions of a particular organism.

Definition

Genetics: Genetics refers to the study of heredity and the variation of inherited characteristics.

Epigenetics: Epigenetics refers to the study of inheritable changes in the organisms caused by the modification of gene expression.

Significance

Genetics: The structure, interactions, function, and alterations of the genes of a particular organism are studied in genetics.

Epigenetics: The modifications of the gene expression of a particular organism are studied in epigenetics.

Fields of Study

Genetics: Genetics covers genomics, transcriptomics, proteomics, heredity, evolutionary genetics, and genetic diseases.

Epigenetics: Epigenetics covers gene regulation, interactions of gene and environment, and the interactions of protein and environment.

Examples

Genetics: In genetics, the combination of alleles in a particular organism is studied.

Epigenetics: In epigenetics, different patterns of methylation and acetylation of DNA and the chromatin state are studied.

Conclusion

Genetics and epigenetics are two fields that study genetic material of a particular organism. In genetics, the structure and the function of genes are studied. However, in epigenetics, the external factors involved in the modifications of gene expression such as DNA methylation and chromatin structure are studied. This is the difference between genetics and epigenetics.

Reference:

1.Mandal, Ananya. “What is Genetics?” News-Medical.net, 18 Mar. 2013, Available here.
2.Davis, Tom. “What is Epigenetics?” Epigenome NOE, Available here.

Image Courtesy:

1. “Chromosome-DNA-gene” By Thomas Splettstoesser (www.scistyle.com) – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Epigenetic mechanisms” By National Institutes of Health – (Public Domain) via Commons Wikimedia