7.2

• Epigenetics


  "Epi" – over, above, outer
• Epigenetics


  Stably heritable phenotype changes in a chromosome without alterations in the DNA sequence
• Epigenetic mechanisms


  • Histone modification
  • DNA methylation
• Epigenomic


  Refers to the study of the complete set of epigenetic alterations
• "Epigenetic code"


  Epigenetic features that maintain different phenotypes in different cells
• Tightly wound DNA


  • Heterochromatin
• Loosely packed, open


  • Euchromatin
• Gene "switched on"


  Active (open) chromatin
• Unmethylated cytosines


  Acetylated histones
• Gene "switched off"


  Silent (condensed) chromatin
• Methylated cytosines


  Deacetylated histones
• Dutch winter hunger - German's blocked food to the Dutch


  Winter 1944
• Calorie consumption


  • Dropped from 2,000 to 500 per day for 4.5 million people
• Children born or raised in this time were small, short in stature and had many diseases including enema, anaemia, diabetes and depression
• The Dutch Famine Birth Cohort study showed that women living during this time had children 20-30 years later with the same problems despite being conceived and born during a normal dietary state