1. Content What is epigenetics?

2. The Mapping of the Human Genome Project 2000 A working draft but completed in 2003 Only 20,000–25,000 genes! Only 1.5% of DNA The regularity section of DNA is at least 50% of genome

3. It is the study of heritable changes in gene expression caused by mechanisms other than changes in the underlying DNA sequence The name epi- (Greek: over, above, outer) –genetics. Changes to gene expression through: DNA methylation Histone modifications MicroRNA These changes may remain for the remainder of the cell's life, but can be reversible & may also last for multiple generations Epigenetics Inheritance but not as we know it!

4. Diseases occur When a mutated gene is inherited & runs in a family Random mutation in the womb or after birth Epigenetics changes caused by environmental factors Other mechanisms that are being elucidated Involvement of DNA repeats Transposable elements & Jumping Genes Bacteriom (affect chromatin structure & transcription

5. Source: Wikimedia Commons-NIH

6. MicroRNA Protein assembly is blocked

7. Repetitive regions of non-coding DNA are conserved within a person's DNA, & they are passed from parents to offspring in a Mendelian way, like genes. Transposon is a small piece of DNA that inserts itself into another place in the genome ‘Jumping Genes’

8. Epigenetics Shatters "The Central Dogma” " The Central Dogma" of molecular biology – one direction DNA makes RNA makes proteins New evidence shows that information flows in both directions, from DNA to proteins & from proteins to DNA. Genes can be activated & de-activated by signals from the environment & this can be reversible Only about 2% of the human genome actually codes for proteins Epigenetics has shown that in addition to nature & nurture, what makes us who we are is also determined by biological mechanisms that can switch genes on or off.

9. A paradigm shift in scientific thinking as it has changed the way causes of diseases are viewed, as well as the importance of lifestyles & family relationships. Epigenetic factors (marks) control many of the normal functions of cells in our bodies. Not all genes are active in all tissues all times. They are activated or silenced according to the needs of particular cells or the whole organism during development & in response to the prevailing nutritional, physical or social environment throughout early life. Even those epigenetic marks that are inherited seem to be subsequently reversible.

10. Epigenetics environmental changes documented in bacteria, plants & animals (insects, rodents & other mammals) Honey bees larvae that develop into workers & queens are genetically identical. As a result of the royal honey diet, the queen will develop functional ovaries & large abdomen for egg laying, while worker bees remain sterile.

11. Workers start out as nurses looking after the queen & larvae & then they become foragers travelling out in search of pollen. The two types have very different DNA methylation Foragers can revert back to being nurses if the hive requires that & their methylation pattern revert back too.