What is epigenetics?
Epigenetics is the study of how cells control gene activity without changing the DNA sequence, influencing how genes are turned on or off.
Overview
The term epigenetic describes factors beyond the genetic code. While epigenetics does not change the sequence of DNA building blocks, it involves modifications to DNA that regulate whether genes are turned on or off. The complete set of these modifications within a cell's genome is known as the epigenome.
These changes influence the production of proteins in cells, ensuring that each cell produces only the proteins necessary for its specific function. For instance, proteins that promote bone growth are not produced in muscle cells. These patterns vary among individuals, across different tissues, and even between cells within the same tissue.
Factors Influencing the Epigenome
The epigenome is dynamic and can be influenced by several factors:
- Environmental influences: Factors such as a person’s diet and exposure to pollutants can impact the epigenome.
- Cell division: Epigenetic modifications can be maintained from cell to cell as they divide.
- Inheritance: In some cases, these modifications can be inherited through generations.
Common Types of Epigenetic Modification
DNA Methylation
This process involves the attachment of small chemical groups called methyl groups (consisting of one carbon atom and three hydrogen atoms) to DNA building blocks. When these groups are present on a gene, that gene is silenced, meaning no protein is produced from it.
Histone Modification
Histones are structural proteins in the cell nucleus around which DNA wraps to give chromosomes their shape. These proteins can be modified by the addition or removal of chemical groups, such as methyl groups or acetyl groups. These chemical groups influence how tightly DNA is wrapped around the histones, which in turn affects whether a gene is turned on or off.
Epigenetics and Health
Errors in the epigenetic process—such as modifying the wrong gene or failing to add a chemical group to a specific gene or histone—can lead to abnormal gene activity. Altered gene activity caused by these errors is a common cause of various health conditions, including:
- Cancers
- Metabolic disorders
- Degenerative disorders
Scientists continue to research the relationship between the genome and the chemical compounds that modify it to better understand their effects on gene function, protein production, and human health.