End of Week 1
Often times, I feel as if we forget that science is often closely flanked by social issues. So far in the course, the ethics of science and in particular, genetics has come up again and again. Professor Ralph Bertrand constantly reminds us to think of the bigger picture and that science should not be studied in a vacuum. He often asks “Why is this important? Why are we teaching this material in the first place?” The answer to these why questions are quite selfish. After all, we live in an anthropocentric society. Studying genetics allow us to better understand how living organisms thrive and propagate, how to mitigate or solve genetic disorders, and how to better the human condition.
On the second day, we had a discussion on genetic mutations and genetic modification. As you all know, the discourse on genetically modified organisms(GMOs) in popular media is not particularly informative nor helpful. A classmate had brought up the question of where you would draw the line in calling something a GMO, afterall nothing is inherently “natural” about the food we eat. Is artificial selection or selective breeding consider part of creating a GMO? Because for a lot of the foods that we eat – corn, almonds, tomatoes and etc, were inedible before selective breeding. Almonds contained a level of cyanide that would have killed us. The precursor to modern corn is a tiny grain called Teosinte, but after years of selective breeding, had finally become domesticated around 6,000 years ago. Is the line drawn at DNA splicing, DNA insertion, or DNA deletion? Is the backlash on GMOs due to the “unnatural” way humans have intervene with “nature”?
In addition to discussing genetics and its role in society, we’ve review the basic tools necessary to study genetics. Things like Western Blots, Northern Blots, Southern Blots, DNA microarrays, and DNA hybridization are all techniques to studying molecular genetics.
A little side note: Whoever said scientists don’t have senses of humor is very wrong. The name of Northern, Southern, and Western blots started because a man name Edwin Southern developed the Southern Blot. The Northern and Western Blots came afterwards as a joke created by other scientists about the cardinal directions and Edwin Southern’s name.
These techniques help study changes in DNA sequences. Single nucleotide polymorphisms (SNPs), short tandem repeats (STRs), and copy number variants (CNVs) can all be detected by these techniques. These different types of differences are helped to differentiate individuals from one another as well differentiate populations. They’re also used to detect defects such as genetic diseases that may be associated with the changes in nucleotide sequences.
Examples brought up in class were about how STRs are used for identification of suspects as well as paternity testing.
There are about 13 core loci looked at by the FBI to check for identity. The way STRs are used for the identification of suspects is to compare unique combinations of STR found in the recovered DNA and the suspect’s DNA. An STR – standing for “short tandem repeat” is a 2 – 6 nucleotide sequence that repeats at least twice in tandem. For example, if the short sequence is “atg” then STR of “atgatgatgatg” has 4 repeats. The number of repeats are unique and are pass down from parent to child. We all have a copy from our dad and from our mom. In this identification, the suspect may have a 4 and 6 copy at STR # 1 and the recovered DNA may have a 4 and 6 copy at STR # 1. This information can not correctly match the suspect to the DNA because many people may have that combination of 4 and 6 at STR # 1. Thus many STRs must be used. The chances of a mistaken identification decreases as the number of STRs increase.
Another usage of STRs is in day time television shows. The Maury Show has been running for over 20 years. One of the big motifs of the show is paternity testing. So if you have ever turned on the TV in the early afternoons, you might have heard the line“YOU are NOT the FATHER” or “YOU ARE the father!” Well paternity testing works very much the same way as the suspect identification mentioned in the above paragraph. However, with paternity testing you need DNA from both parents. The child’s STRs combination is some sort of amalgation of the parent’s STRs combinations.
It’ be a fascinating week thus far. Please continue to follow the progress of our class!
