Epigenetics

Epigenetics is the study of cellular and physiological trait variations that are not caused by changes in the DNA sequence, it aims to describe the alterations in the transcriptional potential of a cell. These alterations may or may not be heritable (1). Unlike regular genetics, which is based on changes to the DNA sequence, epigenetics is the changes in gene expression or cellular phenotype (2,3). These include functional changes to the genome that do not involve a change in the nucleotide sequence. Epigenetic changes may last through the duration of the cell's life and can also last for several generations, even though they do not involve changes in the underlying DNA sequence of the organism's genes (4).

In fact, there is an entirely separate epigenome. Epigenetic tags act as a cellular memory. A cell creates an epigenetic profile, which is a collection of tags that tells genes whether to be on or off and is the sum of the signals it has received during its lifetime. While a fetus develops, gene expression patterns are changing. Epigenetic tags record the cell's experiences on the DNA, helping to stabilize gene expression. Different experiences cause the epigenetic profiles of each cell to grow increasingly different over time. Eventually, hundreds of cell types form, each highly different and specialized. A flexible epigenome allows us to adjust to changes in the world around us, and learn from experiences (5).

Sources: 3. Bird A (May 2007). "Perceptions of epigenetics".Nature 447 (7143): 396–                8.Bibcode:2007Natur.447..396B.doi:10.1038/nature05913. PMID 17522671
 * 1)  Ledford H (2008). "Disputed definitions". Nature455 (7216): 1023–8. doi:10.1038/4551023a.PMID 18948925.
 * 2)  Carey N. (2011): Epigenetics revolution: How modern biology is rewriting our understanding of genetics,disease and inheritance. Icon Books, London, ISBN 978-1-84831-315-6; ISBN 978-1-84831-316-3.

4. "Special report: 'What genes remember' by Philip Hunter | Prospect Magazine May 2008 issue 146". Web.archive.org. 1 May 2008. Retrieved 26 July 2012.

5.The Epigenome learns from its experiences. (n.d.). Retrieved April 3, 2015, from http://learn.genetics.utah.edu/content/epigenetics/epi_learns/