2. What Is Epigenetics?
All the genetic modifications excluding
changes in the actual DNA sequence.
Modifications include adding molecules, like
methyl groups, to the DNA. This changes the
appearance and structure of DNA which
alters how that gene can interact with the
transcribing molecules in the cell’s nucleus.
3. What is Epigenetic
Inheritance?
The fact that non-genetic variations that are
obtained during an organism’s life can be
possibly be passed on to that organism’s
offspring.
An example of this would be that brain and skin
cells have exactly the same DNA, but different
functions and forms. So, there must be
something that makes skin cells stay skin cells
and brain cells stay brain cells when they divide.
4. How Does It Work?
Epigenetic modifications turn genes on or off
which prevents or allows the gene to make a
protein.
One type of modification is DNA Methylation.
The addition of methyl groups to the
backbone of the DNA can help distinguish
the gene copy inherited from the mom or the
one from the dad.
5. Experiments With Epigenetics
When fruit flies are exposed to certain chemicals
they get rough growths on their eyes and at least 13
generations after them are born with it too (and
generations 2-13 weren’t exposed to the drug).
A pregnant rat was exposed to a chemical that can
alter reproductive hormones. It had generations of
sick offspring.
People who aren’t well-fed as a child are known to
have children and grandchildren with higher risks for
diabetes and cardiovascular disease.
6. Experiments with Epigenetics
Smoking and over-eating can make the
genes for obesity over-express themselves
and the genes for longevity under-express
themselves.
Men who smoke before puberty tend to
have sons who can’t produce sperm,
have higher body mass indexes and
shorter life expectancies.
7. Experiments with Epigenetics
The rise in peanut allergies may be because
of baby lotions containing peanut oil.
Pregnant women with high maternal
anxiety are known to have children with
asthma.
Little kids who are kept very clean are at
higher risk for eczema.
8. Sweden Study
In Norrbotten, Sweden in the 19th century
there were very few people. If they had a
bad harvest, people would starve.
1800, 1812, 1821, 1836, & 1856 the crops were
horrible and people suffered.
1801, 1822, 1828, 1844 & 1863 the crops were
bountiful and the people had feasts.
9. Sweden Study
The study showed that pregnant women who
ate poorly tended to have children with a
higher risk for cardiovascular disease when
they got older.
Children that went from having a normal
harvest to a feast the next year were known
to have children and grandchildren with far
shorter lives. When certain socioeconomic
variations were controlled it came out to be
that the future generations would die 32 years
before their peers.
10. Epigenetic Changes
But throughout all of those studies and
experiments, the change was not in the DNA
itself, but the new traits were passed on by
epigenetic means.
Epigenetic changes could possibly be
permanent. The changes represent a response
to an environmental stressor. The response can
be inherited, but once the stressor is taken
away, the marks will fade and the DNA code
will go back to its original programming.
11. Contributions to Science Work
and Society
The new evidence for epigenetic inheritance
has had great implications for the study of
evolution. It extends the span of evolutionary
thinking and is leading to ideas of heredity
that include development. And it also
suggests that acquired traits can be heritable,
so Lamarck wasn’t completely wrong.
12. The Good News
Scientists are learning to manipulate
epigenetic marks and are making drugs
that will treat sickness by turning off the
bad genes and turning on the good ones.
13. Future Implications
Scientists are hoping to develop epigenetic
drugs to help people with diabetes, cancer,
Alzheimer’s, schizophrenia, autism, etc.
They are hoping that further research will help
answer why one identical twin can suffer from
asthma or bipolar disorder and the other one
doesn’t. Or why autism is four times more likely in
a boy than a girl.
