The study of the factors that cause development.
Modifications in the expression of genes that do not involve a change in the base sequence of that gene. This occurs, for example, through the methylation of DNA.
The science of how the activity of DNA (deoxyribonucleic acid, which is the fundamental genetic material of cells) can be altered semi-permanently by chemical processes rather than by natural mutation. Genes contain instructions for making proteins. The natural process of implementing these instructions — gene expression — can be altered by chemical groups attaching themselves to the chemical bases that make up a strand of DNA. This, in turn, affects the generation of proteins from the genes so tagged. Some chemical groups can even stop a gene from being expressed.
Changes in the way genes are expressed that occur without changes in the sequence of nucleic acids. In mammals the most common form of epigenetic change results from methylation (the addition of methyl [-CH3] moieties) to the promoter regions of genes. Although epigenetic changes do not alter the sequence of nucleotides, they are inheritable.