Ghost in your Genes (Documentary)
Identical twins function the same early in life, but function changes over time - why is this? Genes
interacting with environment.
What does tell the whole story about our genes? What else influences our genetic make-up?
Scientists believe that this answer lies in the area between our genes (like dark matter in the universe)
1990s - Human Genome was sequenced and would allow for a greater understanding of how the body
was put together; scientists thought genome would allow for discovery of all disorders and diseases -
thought it would contain around 100,000 genes; slowly it went down to a much smaller number -
humans have the same number of genes as fish and mice (not as complex as even plants!)
Same key genes that make other organisms (e.x. chimpanzees) make out organization! What accounts
for difference in the genome? Genes may not be the whole story...
E.X. Angelman condition - caused by a genetic defect (deletion in chromosome 15) - results in very
happy children, but intellectual issues and walking issues; same deletion also results in a completely
different condition (syndrome resulting in floppy children, then leading to great weight gain)
o Had to do with inheritance - from father, child would get the latter; from mother, child would
get Angelman condition!!
o Must have been an imprint or tag, to tell the now developing fetus to silence or make certain
o First evidence that something other than genes passes to children - tags on chromosomes can
shut off gene expression
Example: mice - twins; both have a genes Agouti - in yellow mouse, it is switched on all the time; mouse
keeps on getting fatter/brain does not tell it that it is full! Methyl molecule is attached to the brown
mouse, which shuts down area in brain that tells you when you are full (like hugging DNA - hugging
tightly = hidden from cell, shutting off gene expression)
Differences in cells from different areas of the body, deals with switching on and off cell components;
switches on cells are very stable
However, some epigenetic tags can be manipulated: in fat yellow mothers fed vitamin rich food (folic
acid, B12) is linked to brown mice that are thin - did not change any chemical letters in the parent or
children, but did affect the children and their potential for disease
Epigenetic helps to describe the expression of our genes (perhaps describes the differences in identical
twins - any difference describes influence of environment (nature v.s. nurture))
o One twin receives disease (e.x. cancer), while other does not!?
o Researchers took DNA from twins, amplified, and ran on gel; cut out areas that had tags
o Epigenome analysis tells us that as you get older, epigenetic changes accumulate in twins (and
everyone else),which greatly affects our genetics
Why does epigenome change, while genome does not?
o Looked at studies with mothers: nurturing and non-nurturing
o Off-spring of non-nurturing mothers in stressful situations had increase in stress hormones and
blood pressure, compared to those of nurturing mothers
o Must be a marker in genes that remembers this fact in genes with mice regarding stress
o Extracted and analyzed genes between high and low nurtured genes
o Less-active genes in neglected genes (could not handle genes n