Most people think that DNA can't be changed as it passes down from generation to generation, but recent discoveries says it can. On page 159, Shenk states that "histones protect DNA and keep it compact. They also serve as a mediator for gene expression, telling genes when to turn on and off." These histone packagings are called epigenomes, which can be altered from the environment. Geneticists Morgan and Whitelaw did an experiment and discovered that "their batch of genetically identical mice were turning up with a range of different fur colors" (Shenk 159). They discovered that these mice changed their epigenomes by what food they ate. Other experiments show similar results of how genetically identical organisms have differences.
Does this mean that a person's lifestyle will affect future generations? How much of an impact will the structure and function of the epigenome have? Do you think people will be able to deliberately change their genes to benefit their children in the future? How? Do you think this discovery will make people work harder in order to achieve success for themselves and their kids?
Anisha Ghosh (anishaghosh16@gmail.com)
In chapter 10, Shenk introduces the concept “lifestyle can alter heredity” (161). The study with the identical mice shows that a person’s lifestyle will affect future generations because if something as simple as food causes a change in the epigenes of the mice that affect future generations than there could be a great many factors that cause changes to the human epigenomes and affect future generations. One example that Shenk used was that exposure to pesticide in one generation led to epigenetic changes that caused low sperm counts over the next 4 generations. The structure and function of the epigenome has a large impact on gene expression and regulation. For example histone acetylation, a type of histone modification where acetyl groups are attached to lysines in histone tails, causes histone tails to no longer bind to neighboring nucleosomes, meaning that chromatin has a looser structure and transcription proteins have easier access to genes in an acetylated region. Campbell points out that “histone acetylation enzymes may promote the initiation of transcription not only by remodeling chromatin structure, but also by binding to and thus ‘recruiting’ components of the transcription machinery” (358).
ReplyDeleteThe discovery of changes in the epigenome carrying over several generations could lead to people trying to change their epigenes to benefit their children in the future and working harder to achieve success for themselves and their children. There are an enormous number of factors that could cause changes in the epigenome but if people knew that “lifestyle can alter heredity” I think they would try to lead healthier lifestyles. The knowledge of epigenetics makes people more responsible for the outcome of their children’s life so I think that they would work harder so that their children could have genes that might make them more successful. In an article in Time magazine, writer John Cloud points outs evidence of “lifestyle choices like smoking and eating too much can change the epigenetic marks atop your DNA in ways that cause the genes for obesity to express themselves too strongly and the genes for longevity to express themselves too weakly” (http://www.time.com/time/magazine/article/0,91 71,1952313,00.html#ixzz1rd9lwcpX). If people were aware of this, then this would give them additional incentive to stop, if not for them than for their children.
Jessica Hua (jhua33@yahoo.com)
A person’s lifestyle will definitely affect future generations. I remember from the video we watched in class it detailed many cases of past generations affecting the health of future generations. I don’t remember the details too well, but I remember that survivors of the Holocaust and all the stress on their body actually changed their genes such that their children were more likely to have mental disorders like depression. Also, the same goes for the survivors of 9/11. Stress has an impact on the body that translates into genes and subsequent generations. The epigenome is the changed gene expression or phenotype caused by chemicals that activate particular genes.
ReplyDeleteThere are many factors that can change the genome of a human and affect their children’s genome. People could try to change the genome so that their children will have specific, desired qualities, but I think that is a very futuristic, unrealistic option anywhere soon. I think this discovery will make people take care of their bodies more if not for themselves but for their children. They will be more careful in their potentially destructive habits and keep themselves stress-free and safe so that their genome is not changed and reflected badly onto their children.
Like the Peloria toadflax flower example in the book, Shenk makes it clear that the “epigenome had subsequently been passed down through many generations” (159). The genomes don’t just magically get “wiped clean like a blackboard with each new generation” (159). Everything is much more complicated than that. The concept of epigenetics, proved example after example, is monumental to the life of future generations, for good or for bad. For disease or for biological advantages.
Gabriella Veytsel (geminizire@hotmail.com)