Upon the Genome is the Epigenome

Researchers are beginning to understand why cells have specialized rolls when they maintain the same genome.  This has been one of the many mysteries of biology that is beginning to be debunked.

According to MedicineNet.com a genome is all of the genetic information, the entire genetic complement and all of the hereditary material possessed by an organism.

It is understandable why there would be some confusion on how cells posses different duties when all of the bodies cells, for example with the human genome, contain the exact same genome.   Two types of genomes actually make up the entire genome; the chromosomal genome, inside the nucleus, and mitochondrial genome, outside the nucleus.

Researchers are finding that a second layer of information is embedded in the special proteins that package the DNA of the genome.  The second layer is referred to as the epigenome and controls access to the genes.  The epigenome, epi- meaning “on”, “upon”, or “at”, not only allows each cell type to activate its own special genes but blocks off most of the rest and also controls when the accessible genes may be activated.

The epigenome controls many things and changes with age.  Any change is the epigenome can have devastating effects on the cell which may contribute to disease or cancer.

To put it into perspective, twins look and behave differently because of changes in their epigenome as they grow older.  A single person has only one genome but many different epigenomes.

According to an article in the New York Times, the epigenome may hold the key to the dream of regenerative medicine.

Regenerative medicine involves using the bodies own mechanisms to heal it, deriving safe and efficient replacement tissues from a patients own cells.

The epigenome is composed of many chemical modifications, or marks, along the material the makes up the chromosomes, or chromatin.  The chromatin, which is located in the nucleus, is a mass of genetic material composed of DNA and tightly woven proteins.  Chromatin regulator proteins recognize and preform the tasks indicated by the marks.

In some marked domains, regulator proteins cause the DNA to be so tightly wound that the genes are permanently inaccessible.  This gives reason as to why the cell can only preform certain functions.


~ by awhite2 on November 1, 2009.

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