Epigenome

Visit the learn.genetics website and visit each of the following sections on the epigenome.  Record your information in your genetics reflection blog.

IDENTICAL TWINS: PINPOINTING ENVIRONMENTAL IMPACT ON THE EPIGENOME

   1. Often, the physical characteristics of genetically identical twins become increasingly different as they age, even at the molecular level. Explain why this is so. (use the terms "environment" and "epigenome")

Physical characteristics of twins become very different over time because they are exposed to different environmental factors. If one twin ate healthier than the other, then that would leave a different epigenetic tag then the twin that ate more junk food. The epigenome changes between the twins, so by the time they are old, they have very different epigenetic patterns. 

   2. Name 3-4 environmental factors that influence the epigenome.

Factors that influence the genome are: exercise, diet, toxins, and stress. All of these factors are introduced in our daily lives. 

   3. What is an imprinted gene?

An imprinted gene is an epigenetic tag that is passed on to the offspring. 

YOUR ENVIRONMENT, YOUR EPIGENOME

1. Discuss factors in your daily life (ie. Diet, exercise, stress etc.) that could be affecting your epigenome

Diet could be changing my epigenome, because  I don't eat a lot of vegetables. I do get a lot of exercise, which changes the way I look and my body type, which is signaled by my genes. Stress could also be changing my epigenome. When I get stressed it takes a toll on how I feel. Finally, toxins could be influencing my epigenome, such as polution from cars, second hand smoke, and industrial waste. When these travel through the air they can cause allergies and trigger asthma.

LICK YOUR RATS

   1. Explain how a high-nurturing mother rat shapes her pup's epigenome, and what that pup's response to stress will be.

A high-nurturing mother rat shapes the pup's epigenome by licking it constantly. When the mother licks and grooms the baby rat more, the GR gene becomes more active, making the pup have an easier time with recovering from stress. The gene will most likely stay the same throughout the rat's life.

   2. In rats, does licking by the mother activate, or deactivate her pup's GR gene?

It activates the GR gene. That means that the pup will have an easier time to relax after it gets stressed.

   3. Explain how cortisol and the GR protein work together in the brain to relax a rat pup. You may draw a diagram.

When the cortisol travels to the hippocampus (area of the brain) it binds with the GR proteins to help the rat get less stressed and recover from the stress more quickly.

   

4. The rat nurturing example shows us how parental behavior can shape the behavior of their offspring on a biochemical level. Relate this to humans and think about the personal and social implications. Record your thoughts.

Mothers who care for their children in a more nurturing way shapes how the children grow up. If you grow up in a very stressed household, you are more likely to become stressed. Children learn from their parent's behaviors and replicate them. It can also be a little like a cycle of violence. Abused children are more likely to be bullies in school and get involved with drinking and drugs when they get older.

NUTRITION & THE EPIGENOME

   1. Explain how the food we eat affects gene expression.

The nutrients we extract from food can enter our metabolic system and are changed into molecules we can use. They are turned into methyl groups along a pathway. When chemicals and additives from the food enter the body, they can change the epigenome. 

   2. Can the diets of parents affect their offspring's epigenome?

Yes. During early development, what the mother eats can affect the offspring for the rest of its life. Studies show that a mother with a methyl deficient diet will have methyl deficient children. In rats, the unhealthy rats were given a methyl rich diet and the offspring turned out healthy. The father's diet can also influence the child.

EPIGENETICS & THE HUMAN BRAIN

There are many epigenetic factors that influence behavior. 60% of genes differ between psychiatric patients and normal people. Child abuse is an environmental factor that that leaves a genetic mark on the brain, and in comparison of suicide victims, only abused people had tags on the GR gene.  Some drugs that treat mental illness change the gene expression. Drugs of abuse, such as cocaine can affect hundreds of genes at one time, and the effects can be written into the genetic code. 

People that committed suicide have higher methylation than normal. Children who were abused made up most of the suicide victims. The only differences between the suicide victims and normal people were found in the hippocampus of the brain.