What is the difference between epigenetics and epigenomics?
In eukaryotic cells, the DNA is packaged within the nucleus in a structure called chromatin. This structure is a highly dynamic nucleoprotein complex that plays a central role in regulating how and when DNA is copied and transcribed into RNA. Thus chromatin states vary from cell type to cell type and along chromosomes. The epigenome refers to these states at the whole genome level. Typically, a multi-cellurar organism will be characterized by one genome, but by as many epigenomes as there are cell types.
Epigenetics encompasses all processes that lead to heritable changes in gene expression (during development or across generations) without changes in the DNA sequence itself. In eukaryotes, chromatin is at the heart of most epigenetic processes. Thus, the study of epigenetics often crosses that of epigenomes (epigenomics).