Epigenetics

• Epigenetics

  Phenomena where due to lifestyle and environmental exposure gene expression is altered
• signalling to RNA polymerase

  upstream of promoter there are enhancers positioned to enhance transcription. they position activators correctly, this helps to further promote RNA polymerase correctly
• lactose expression

  -normally without lactose, repressor proteins prevent RNA polymerase from binding and transcribing genes for lactase

  -with lactose preset, lactose binds to the active site of repressor removing it from the promoter region allowing for RNA polymerase to bind to promotor region allowing for transcriptions of genes needed to make lactose
• nucleosomes

  -core, octamer of histone proteins a and positive charged

  -wrapped twice by negatively charged DNA

  -linker DNA, between nucleosomes, is more easily accessible to RNA polymerase, more easily transcribed and expressed into a protein or characteristic
• DNA methylation

  methylating the promoter prevents RNA polymerase from binding meaning cannot transcribe the target gene. gene is turned off
• Histone modification

  histone tails have lysine residue, these can have Epigenetics tags added to them due to lifestyle exposure
• methylation of histone tails

  cause the DNA to wrap more tightly around the histone proteins/ nucleosome. this will mean RNA pol can’t bind as easily causing loss transcription and less expression
• acetylation of histone tails

  cause the DNA to wrap loosely around the nucleosomes RNA polymerase upstream can wrap more easily bind causing more transcription to occur and more expression of proteins
• Epigenetics case study one

  initial environmental exposure- starvation and lack of calories for pregnant woman

  in pregnant women and their developing baby’s, genes to regulate cardiovascular health, weight gain and schizophrenia had Epigenetics tags added to them and those tags were silenced

  40 years later in offspring there was an increase in cardiovascular disease earths, obesity and mental health issues
• Epigenetics case study 2

  monozygotic twin studies are incredibly useful to scientists when looking at Epigenetics

  differentially methylated regions change due to environmental exposure

  it enables scientists to study whether their is an epigenetic link to disease and wether specific methylation patters lead to disease development
• Epigenetics case study 3

  nitrogen oxides, poly-aromatic hydrocarbons are toxic compounds in pollution. the immunoregulatory genes become methylated this leads to increased inflammation and an altered immune profile, causes high blood pressure and respitory conditions
• removal/imprinting of Epigenetics tags

  germline tissue - existing tissues containing established Epigenetics tags

  gametes- removal of Epigenetics tags mostly

  developing embryo - increase in epigenetic tags to cause differentiation- Epigenetics

  • the progress of development of a complex multicellular organism from an undifferentiated pluripotent cell is called epigenesis
• medium sized tigon

  medium male tiger + not big female lion
• very big liger

  medium female tiger + big male lion