Question: What does ep..........  Edit

Answer: Epigenetics is the study of heritable genetic information that does not involve changes in the nucleotide sequence of DNA, but, is manifested as chemical marks that are added to either DNA or chromatin proteins following replication. Examples of these marks are DNA methylation and histone modifications such as acetylation and methylation (causing chromatin remodeling). These marks are part of the complex regulatory system that control gene expression and that, along with siRNA and the proteins that initiate transcription, are called transcription factors.
Several different types of epigenetic events have been identified. As described in the section above relating to chromatin structure as a means to control gene expression and the role of DNA methylation in these structural changes, DNA methylation is likely to be the most important epigenetic event controlling and importantly maintaining the pattern of gene expression during development. Other DNA modification events are also known to effect epigenetic phenomena including acetylation, methylation phosphorylation, ubiquitylation and sumoylation of histone proteins. Thus, it should be clear that the same events that affect chromatin structure can be defined as epigenetic events. An additional process that affects chromatin structure and therefore gene expression is considered an epigenetic event and this involves the small interfering RNAs (siRNAs) described below.
Whereas, epigenesis plays a vital role in the regulation, control, and maintenance of gene expression leading to the many differentiation states of cells in an organism, recent evidence has identified a linkage between epigenetic processes and disease. Most significant is the link between epigenesis and cancer which has been suggested to be a contributing factor in nearly half of all cancers. A clear demonstration has been made between changes in the methylation status of tumor suppressor genes and the development of many types of cancers. Epigenetic effects on immune system function have also been identified. In addition, there is evidence suggesting a link between epigenetic processes and mental health.
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