Q1:1. Explain what epigenetics is
There is a relatively new branch of genetics that is called epigenetics, which provides information that how can environmental factors or life style changes can affect the expression of genes without causing changes in the nucleotide sequences of the genes.
You can think about epigenetics as *Tags* which can switch genes on and off just like when we turn a lamp on it produces light and when we turn it off light donot shines.
So, how epigenetics regulates the expression of DNA is mainly through two mechanisms:
1:Covalent modifications of DNA through mechanisms like hydroxymethylation and cytosine methylation
2: Modification of histone proteins through lysine and arginine methylation, lysine acetylation and serine and threonine phosphorylation.
We won't go in detail of the mechanisms through which these modifications work but we will focus on the results of these mechanisms. These mechanisms turn different genes on and on and also differentiate one cell from another like skin cell is specified to perform its activity and brain cells are specified to perform their activity.
Similarly, some genes are expressed only upon the time of adolescence by promoting the expression of secondary sexual characteristics, like beard formation etc these genes are also an example of epigenetics.
Similarly, environmental factors affecting gene expression also come under epigenetics. For example, In some people of fair complexion, the production of melanin increases and causes freckles and pigmentation upon sun exposure. This is because genes of melanin production are turned on in those people under UV light. This is also epigenetics.
Q2:Explain Michael Meany experiments on rat mamas and what he learned.
Michael Meany was a specialist in the field of neurology, neuro psychaitry and  neurosurgery but he is famous for his work on epigenetics and regulation of stress responsive genes.
In one of his experimentation, he analysed the behavior of rat pups who were given maternal and not given maternal care. The purpose of his work was to find the relation between mother care and pups response to stress.
In his experiment he used two groups of rat pups,in  one group the mother rat was high licking and grooming (HHG) and in other group the mother was low licking and grooming (LLG).
This means that the mother of first group was more caring than the mother of second group.
Michael Meany observed that pups of HHG mothers had greater density of Glucocorticoid receptors (GRs) than the pups of LLG mothers.  GR binds to glucocorticoids, and regulate the expression of many stress responsive genes. GR has alot of importance in neurosciences by integrating the neuro endocrine glands and  alleviating the stress response.
By this research Michael Meany proved the causational relationship between mother care and stress response. It was also an example of epigenetics where mother's behavior cause modification of pups' genetics.
3.What life style events can affect your biology?
So, how our life events affect our biology are through several ways.Dr. Rudolph Tanzi is a professor at Harvard university who showed that factors like diet, sleep, behavior and other environmental circumstances can affect our biology by triggering specific genes on and off.
For example: the studies showed that only one week of insufficient sleep can alter the activity of almost 700 genes by triggering different processes like stress, anxiety, mood swings etc.
Similarly, if we have a life style where we feel positive about everything, feel gratitude about blessings then it has shown to positively regulate the activity of genes by causing mind freshness and calmness and more stability of moods.
Similarly, diet can also affect our biology in several ways. For example:  a diet that is excessively rich in carbohydrates can attack our genes and cause disbalance in blood glucose levels. While a diet rich in sulforaphane, resveratrol  and epigallocatechin gallate (green tea) can reverse the damage to DNA and promote a good health.
Hope it help!
