Teenage Mutant Electrophoresis

   DNA testing has opened a completely new realm of scientific possibilities. The process has evolved over the years from a tedious task in which a lone scientist charted nucleotides by hand to a routine procedure often rapidly performed by robots. The technique has numerous applications, including testing for evolutionary relationships, crime scene investigation, testing familial relationships, and individual testing for genetic predispositions for certain diseases.
   In our lab, we will be testing for a hypothetical disease, as disease testing is unethical in a high school environment. The gene for the "disease" we will be testing for comes in two separate forms: a long, sterile segment and a short, disease-causing segment. The short form is a recessive disorder, so we will need two copies (homozygous recessive) to have the predisposition. With Polymerase Chain Reaction (PCR) we will be able to target and amplify this specific gene, although in reality it is an intron that does not code for protein.
   There are several techniques for DNA testing, but we will be using gel electrophoresis. First, we need to extract our DNA, which we will take from cheek cells. After rinsing with a saline solution and collecting the cells, we will put the cells in a 95-degree Celsius water bath to break through the cellular and nuclear membrane. Hiding in the cytoplasm, however, are enzymes called DNAse that kill any DNA they find. This is a protection against foreign DNA, like from a virus, but it cannot tell the difference between viral DNA and its own genetic material. Therefore, we will add Instagene Matrix Beads that dismantle DNAse and allow us to extract our DNA, unharmed.
   This will be a tiny amount of DNA that won't be visible on a gel, so we must amplify the genetic material using PCR. PCR requires primer for our specific sequence, ample DNA nucleotides, DNA polymerase, and DNA ligase. During PCR, our DNA samples will rapidly replicate by a power of 2, giving us more than enough material to be seen in gel electrophoresis.

Lane 1 represents an individual with the genetic disorder (homozygous recessive). The recessive gene is smaller, so it travels farther in the gel. Lane 1, therefore, must have two copies of the recessive gene because there is only one band.
Lane 2 is homozygous dominant and does not have the disease. There is one band that did not travel very far, so it must represent two copies of the larger, dominant gene.
Lane 3 is heterozygous and doesn't have the disease. There are two bands, so it must have had one copy of each type of the gene.

 I'm not diseased!!! At first I believed I was diseased because I only saw one solid band designating the recessive gene, but there was a faint semblance of a band below it, meaning that I am heterozygous- a carrier. David and Taylor are diseased because they just have one far-traveling band. Schuyler is homozygous dominant, having zero copies of the disease gene.
There were some potential sources of error, but we avoided them. We loaded our gel properly, not puncturing the well or contaminating lanes with incorrect sample. Overall, this lab went perfectly.