Epigenetics

• Epigenetics


  Means "above genetics" which are caused by modifications of gene expression rather than change in the DNA sequence, resulting in different phenotypes
• Epigenetic Factors


  External factors which change genes, but not the base DNA sequence
• Epigenetic Tags


  Labelling DNA with methyl or acetyl groups which can either silence genes or make them active.
• Methylation


  The addition of methyl groups onto DNA to tighten the packaging of DNA around histones usually to repress gene expression.
• Acetylation


  The addition of acetyl groups onto DNA to loosen the packaging of DNA around histones usually to promote gene expression.
• Epigenetic tags remain for the life of a cell and are passed down to all daughter cell that cell produces.
• Epigenetic tags are not passed down to the next generation as the DNA of a fertilised egg is cleared of epigenetic tags
• Epigenetics is the study of how cells with identical genotypes can show different phenotypes.