Introduction:
Every person in the world has their own unique DNA fingerprint DNA fingerprinting can help to identify and compare individuals. Much of every individuals DNA is the exact same. This makes it difficult to distiguish different people. Microsatellites are used to make this identification easier. Microsatellites are short pieces of DNA that repeat many times in one's DNA sequence. Any biological material can be used for DNA fingerprinting such as, body tissues, body fluids, and hair. Even some dired material such as blood stains can be used. To create this DNA fingerprint from the DNA restriction enzymes must be used.
Restriction enzymes act like small DNA scissors. These enzymes recognizes specific base pairs that tell it to cut the DNA at that point. The spots in which the enzymes make the cuts are called restriction sites. This can result in many different pieces or fragments along one DNA strand. Once the DNA has been cut it can be seperated by the size of the fragments. This seperation is created by using a process called Agarose gel electrophoresis. This process consists of inserting the DNA into an agrose gel slab and passing an electircal current through it. The DNA fragment (which are negatively charged) are attracted to the postively charged end. This is the point in the process that creates the seperation. The bigger DNA fragments are unable to pass through the gel as easily as the small fragments consequently causing them to not travel as far. All of the fragments that are the same size come togethor to form bands. Once the gel is stained we can see these bands. This final result of the way that they line up is the DNA fingerprint.
Results/Observation:
Lane 4 or sample number 3 ended up matching the the crime scene DNA from lane 1. All of the other lanes had differing results with the strips being at different places along the gel. The crime scene matched perfectly to sample 3 which happened to be the sample from Katie Records.
Discussion:
The gel ended up working correctly and the restriction enzyme obviously did its job as the molecular scissors. The smaller pieces moved farther along the gel as expected compared to the larger fragments that didn't make it as far. Some possible sources of error could have been the loading dye not weighing down the sample and the DNA floating out and mixing with the other DNA. Another source of error could have occurred when undergoing the difficult task of inserting the samples into the small slots in the gel. Although some incidents did occur, we were able to work past these and receive the correct results.
Sources:
McGuigan, Brendan. "What Is DNA Fingerprinting?." wiseGeek. wiseGeek, 08/9/2010. Web. 25 Oct 2010. <http://www.wisegeek.com/what-is-dna-fingerprinting.htm>.
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