Epigenetics by sachin


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Epigenetics by sachin

  1. 1. BY SACHIN NARWADIYA Scientist B Vigyan Prasar 1
  2. 2. ◦ Epi-: Greek root meaning upon, over, or above ◦ Epigenome: A system whereby individual gene sequences (stretches of DNA) could be turned on or off or made to function at higher or lower levels ◦ Epigenetics: Modifications of the genome, heritable during cell division, that do not involve a change in the DNA sequence. 2
  3. 3.  Epigenetics simply meant “developmental genetics,” i.e, the study of the way the DNA code of genes is translated into the bodies and physiologies of organisms.  It involves understanding how genes are turned on and off in different tissues and cells,  How different genes interact with each other, and how the products of a one-dimensional sequence of information can build a three-dimensional body. 3
  4. 4.  The second meaning of “epigenetics” is more recent, and involves actual changes in the DNA itself that are not based on mutational changes in nucleotides, but in environmental modifications of nucleotides—things like methylation of nucleotide bases or changes in DNA-associated proteins like histones—that can temporarily modify genes and affect their actions. 4
  5. 5.  The list of covalent modifications to histone proteins continues to grow. (Review by T. Kouzarides).  However, only recently has genetic and biochemical evidence converged to clearly connect covalent histone modifications with longstanding epigenetic phenomena. 5
  6. 6.  Drosophila genetics provides another link between epigenetics and histone modifications, in the form of two evolutionarily conserved families of proteins that regulate homeotic genes antagonistically during development: the Polycomb Group (PcG) and the Trithorax Group (TrxG). 6
  7. 7.  Recently, it has become evident that RNA, particularly non coding RNAs, have a hand in controlling multiple epigenetic phenomena (Bernstein and Allis, 2005). 7
  8. 8.  There is not the slightest evidence that the findings of epigenetics will dispel the main ideas of neo- Darwinism, which include  The ideas of evolutionary change via natural selection and genetic drift  The randomness of mutations,  The ideas of speciation and common descent, and  The gene-centered view of evolution. 8
  9. 9.  There are several definitions of “epigenetics” (it once meant simply “development”), but Burkeman uses the term in its more modern sense as “inheritance not based on coding changes in the DNA.” 9
  10. 10.  Burkeman cites a couple of recent studies in which nongenetic, developmentally caused changes in an organism (like alterations in physiology due to starvation) can be passed on to one or two generations of its descendants.  The offspring of stressed Swedish chickens, for example, have difficulty navigating mazes. 10
  11. 11.  Silent Features:-  There is random variation of phenotypic traits.  There is some ecological variable that is sensitive to the strength of the correlation of such traits with fitness. 11
  12. 12.  There is some mechanism that alters the relative frequency of the trait in the population so that, all else equal, it varies with the strength of the correlation between the trait and fitness. 12
  13. 13.  For example, suppose random variation produces a trait that tends to make its bearers invisible to their predators.  Then, all else equal, the predators gobble up the creatures that don’t have it, and the relative frequency of the trait in the population increases from generation to generation. 13
  14. 14. • The experiment also found that 166 fathers in the study had started smoking before age 11 (right before the body goes through puberty) o Sperm could have been effected by epigenomes, changed by the early smoking. • Sons of the 166 fathers on average had a higher BMI than other children 14
  15. 15. • Scientist are further researching Epigenetics because, if they are able to be controlled, it would be helpful in the medical world o Trying to develop medicine that is able to turn off a negative epigenome and turn on a positive one. 15
  16. 16. In 2004--the first epigenetic drug was approved  Azacitidine  Treats deadly blood tumors/cancers etc.  Life expectancy is expanded by 9 months+ • Scientists are trying to develop other medicines that manipulate epigenomes for Cancer, Schizophrenia, Autism, Alzheimers, Diabetes, etc. 16
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