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Epigenetics Questions Jessica Lewis C Block 1. How does methylation and acetylation affect transcription? What part of the genome is modified? Methylation and acetylation affect transcription by the different enzymes, in this case a methyl group or an acetyl group, attaches to a histone, which add or take away tags from the chromatin. These tags are then read by other proteins, telling the chromatin to either condense or loosen so that other proteins can either repress or further activate transcription. 2. What is the literal definition of “epigenetic”? Formulate a more comprehensive, working definition based on this article. Epigenetic literally means above, or in addition to genetics. In more comprehensive terms, epigenetics is the study of gene expression, referring specifically to factors that are not controlled by the DNA sequence; generally this means outside factors or other conditions that can affect gene expression without changing the content of the DNA. 3. How does cocaine affect epigenetic control of gene expression? Cocaine affects epigenetic control of gene expression by unwinding histones, this changes means that genes are more susceptible to being expressed, because the genes are not as tightly coiled and inaccessible as before. If an animal receives cocaine chronically it can make many different genes in the brain’s reward center. Cocaine turns on many more genes than are normally on, resulting in desensitized genes in some cases, while in other cases, the genes become overactive for extended periods of time. Cocaine’s loosening of histones, sets all of these results into motion. 4. What was the evidence in mice that epigenetic modification could last throughout a lifetime and even in multiple generations? Evidence of epigenetic modification lasting throughout a lifetime first has evidence in the study of depressed mice. After being exposed to social situations that would further induce depression, the mice, particularly with mice of a gentle nature, should strong signs of depression. It seems that through methylation many genes in the mice’s brain were affected so that the mice could not feel good. While antidepressants did help, it is still true that many of the genes were altered chronically or permanently. Epigenetic modification is also shown to last through multiple generations in the case of the mice’s maternal actions towards their offspring, and the resulting maternal actions of those offspring. A receptor in genes receives hormones that then affect the methyl groups in the genes of the offspring based on their anxious, fearful feelings (or lack thereof). This is exemplified with mother who is easy-going and attentive causes methyl groups to be removed in the children, so that they are also easy-going, attentive mothers as a response to how the mother nurtured her pups. The mother who was more hostile and inattentive, had children that were also hostile and inattentive because methyl groups were evident on genes, due to how the mother raised her pups. 5. After reading the article and exploring the website, what is your impression of epigenomics? Support your opinion with at least two more examples you discovered on the website. Where do you think we may feel the most impact from research in this field? After exploring the website, I am believe that epigenetics have a very large role in gene expression. I think it’s very important that we try to control the factors that are within our reach, so that we can prevent the unfavorable effects of epigenetics. I gathered this by doing the interactive rat experiment, that lets you act as the mother rate, and see how nurturing the mouse pup, really affects how tightly wound the chromatin is. I also believe this even after reading about epigenetics and inheritance. Even though part of it states the difficulty of proving inheritance due to the other possibilities such as ruling out the possibility of genetic changes. However after reading the part of the section that gives the example of how what a grandfather eats when he is in his slow growth period, in some studied cases, has shown that this will affect his sperm because this effects the how his epigenome is replicated, which then affects future generations. Studies like this, and studies in rats and other organisms, provide reasonable background for the possibility of epigenetics. While it is very difficult to be certain of epigenetics, I still think it is important to continue studies so that we can learn more about epigenetics and then use that information to our advantage. I think we would feel the most impact in the area of psychological disorders, such as depression and schizophrenia. By studying epigenetics, it is possible to see where the genes experience damage, and how this results in affected gene expression in the brain. By identifying these factors of gene expression, medication can be adjusted or further looked into. Of course, this is a long, difficult process, but by looking further into epigenetics, perhaps the field of psychological disorders can be further explored.