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Epigenetics

Aashika Duvoor

September 22, 2020          

 

          Let’s pretend you have an identical twin. Naturally, you and your twin share exactly the same
DNA, but you are introverted and like staying at home watching Netflix while your twin is the
exact opposite. They like screaming, going to parties at 1am, and are overall a social butterfly.
Wait...but how is this possible? You both share the same DNA. How are you so different?
          The answer: Epigenetics.
          Well let's think of it this way. Both you and your twin have billions of identical DNA cells. But just
because the cells have the DNA, it doesn’t mean that they know what to do with it. They need
outside instruction from methyl groups which are carbon atoms bonded to three hydrogen
atoms. Methyl groups bind to genomes, and when they bind to a genome, it tells that gene “DO
NOT EXPRESS.”
          So for example, you and your twin could potentially be equally skilled at running. But in your
body someone from the methyl group family is bound to the gene in charge of running, telling it
to not express itself, which is why you are slower than your twin when it comes to running.
Epigenetics is also controlled by another family —- the histone family. These guys tell genes to
express themselves either a lot or a little. When a DNA stand wraps tightly around a histone,
that means that the gene is being suppressed. Comparatively, when a DNA stand wraps loosely
around a histone, that means the gene is being expressed.
          It’s sort of like the methyl group is a switch that turns the genome on and off while a histone is a
knob that changes how much a genome is expressed. Another way to think about it is that the
DNA/ the genome is the hardware or the physical device, while epigenetics is the software, or
the specific instructions that make us different.
          Every cell in the body has a distinct methyl and histone pattern, and the methleys and histones
of a certain gene are called its epigenetic tags, and at first scientists thought that all epigenetic
tags were stripped off when passing it from one generation to the next. They believed that a
mom would only pass her genomes down to her child, not her epigenomes. But a study done by
researchers at McGill University involving rat moms’ licking patterns proved otherwise. Some
moms rats lick their rat pups, some don’t, but most in between. The study observed that those
rats whose moms licked them frequently as children grew up more safe, loved and less stressed
compared to their counterparts born from moms who didn’t lick their pups as much. These rats
were constantly stressed and displayed sins of anxiousness. More importantly, the rats passed
the licking/non-licking traits that they received from their mother down generation after
generation. But maybe licking vs non-linking is just genetic? Well, that’s why the research
switched the rat pups. They placed a rat pup from a biologically non-linking mother with a licking
mom, and these rats passed a licking gene to their children. The results were the same when
rats with biological licking moms were placed with non-licking foster moms. So it has nothing to
do with genetics and everything to do with epigenetics.
          This makes scientists believe that epigenetics are passed down from generations. BUT this
doesn’t mean that the epigenetic tags are permanent. They change over time and through your
lifestyle choices. In fact recent evidence suggests that a bad diet can cause methyl groups to
bind to the wrong type of genomes. This helps us understand how epigenetics malfunctions
create diseases and can help us accurately predict and invent drugs to stop these methyl
groups from binding to the wrong genome, preventing its expression.


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