Biological information is two-fold at each level. Don’t get what I mean? Any population is the result of dynamic interplay of its gene pool with the selection pressure acting on it. Similarily, each individual phenotype results from the interaction of genotype with the environment. The three-dimensional information of the proteome (the entire protein complement) is influenced by the proteins’ micro-environment constituted by pH, temperature and so on. At the finest level of the linear information of the epigenome, the complementary information comes from the epigenome. Epigenetics refers to the study of any potentially stable and heritable change in expression resulting without any change in the DNA sequence.
Every cell in an individual has the same genetic makeup. Yet, there are a wide variety of cells in our tissues. This diversification results from the fact that only a subset of the total genome is expressed at any given point across space and time. What tells a cell that which subset of the genome would be expressed and when and how much? The epigenome. The ENCODE project, released in September 2012, proved that what we considered as the junk DNA was not junk after all.
Here is a TED talk by Courtney Griffin. She studies enzymes that are involved in switching on or switching off some genes. These relax the otherwise tightly-coiled DNA. Her study focuses on genes involved in development of blood vessels and their epigenetic regulation.
Read her full paper here:
Griffin. C., Brennan, J., Magnuson, T., The chromatin remodelling enzyme BRG1 plays an essential role in primitive eryhtropoiesis and vascular development, Development, 2008