The Evidence – David Shenk notes that the media is partly at
fault for society’s understanding that genes alone directly determine our
characteristics (17). He cites examples of the media reinforcing this incorrect
theory. However, Shenk noted a more recent New York Times publication that
acknowledged “a revolutionary understanding of genes” (178). The article
mentions that “other molecules clinging to DNA can produce striking differences
between two organisms with the same genes” (178). What are these other
molecules the author refers to and how do they effect gene expression?
Lizzy Ettleson, lettleson@gmail.com
It is clear that our media has endorsed types of genetics lies in a way by supporting theories proposing that “genes dictate. Genes instruct. Genes determine” (17). This media phenomenon has created feelings of a strict pattern of inheritance as opposed to an open field of genetic study. We even see this in our own class, as we had a whole unit in which we studied the basics of Mendelian genetics, a fairly unrealistic occurrence in the world of biological genetic sciences.
ReplyDeleteNow, throughout the last century science has progressed immensely and gene expression is considered to be much more than dihybrid crosses. Phenomena such as the editing process where exons are kept and introns are deleted from the DNA sequence, or alternative slicing which allows a single gene to have the capability to build numerous proteins have evolved in understanding and expanded the scientific field of epigenetics. Now, the growing theory that Shenk supports in his book is that genes are not a strict instruction book for traits but rather a suggested road map that affects their expression. One kind of exception to basic conceptions of genes is epigenetic marks. Epigenetic marks are crucial in determining how a human being is put together and how certain cells are differentiated during “developmental regulation” (http://www.epigeneticsandchromatin.com/content/3/1/2 ). One sort of epigenetic regulation process that involves addition of “other molecules…to DNA” is the act of methylation, where “a methyl group (-CH3) is added to position five of the cyto-sine ring in a DNA molecule,” changing the tertiary and secondary structure of the DNA molecule (http://www.answers.com/topic/methylation-1). This can lead to the repression of a gene and consequently less or altered gene expression as active sites of proteins are now not able to bind to the normal site of the DNA. This act of epigenetic regulation is an example of the body’s attempt to alter gene expression independent of the actual gene information itself, and will only be more clarified in understanding in the next few years to come as epigenetic sciences advance.
Lily Walker (lwalker220@gmail.com)