Epigenetics

Epigenetics

The term epigenetics describes the molecular mechanisms that lead to both stable and dynamic modifications of gene expression; in practice how the variations of the context (environment) can modify the regulation of the DNA. Epigenetic processes involve the activation or silencing of gene expression and influence the phenotype without altering the genotype.
The word “epigenetics” has etymological roots in ancient Greek. It comes from the combination of two Greek terms: “epi” and “genetics”.
“Epi” (ἐπί): In Greek, “epi” means “on”, “beyond”, “above”, or “around”. In a scientific context, it can suggest the concept of superimposition or modification on something pre-existing.
“Genetics” (γενετικός): This word comes from “genesis” (γένεσις) which means “birth”, “origin” or “creation”. “Genetics” refers to the science of studying the heredity and transmission of biological traits from one generation to the next.
Epigenetics is therefore a field of biology that studies heritable changes in gene expression and phenotype (the observable characteristics of an organism) that are not caused by changes in the DNA sequence itself. In other words, epigenetics deals with how genes are turned on or off without altering the nucleotide sequence in the DNA.
Major epigenetic modifications involve processes such as DNA methylation and modifications of histone proteins. Here is a brief explanation of these two changes:
– DNA methylation: This is one of the most studied epigenetic modifications. It involves the addition of methyl groups (CH3) to DNA nucleotides, affecting the availability of genes for transcription. Methylation can silence gene expression, preventing proteins involved in transcription from binding to DNA and activating the gene.
– Modifications of histone proteins: Histones are proteins around which DNA wraps to form the structure called chromatin. Chemical modifications of histone tails can affect how DNA is packaged and accessed. Some modifications can make genes more activateable, while others can repress gene activity.
Epigenetics has an important role in development, cell differentiation and response to environmental stimuli. For example, the cells in our body have the same genetic material (DNA), but epigenetics determines which genes are active in each cell type, allowing for the formation of different types of tissue and organs.
Furthermore, epigenetic modifications can be influenced by environment and lifestyle. This means that experiences, environmental exposures, diet, stress and other factors can influence epigenetic changes, which in turn can affect health and susceptibility to disease.
Epigenetics has significant implications in various fields, including medicine, evolution, agriculture and toxicology, as understanding how epigenetic modifications affect gene expression could open new avenues for treating diseases or improving crop production.