October 23, 2009
All human beings have genomes, or DNA that include all of their unique genetic information. Every strand of DNA is different per individual, which accounts for human diversity in the world. Variable Number Tandem Repeat (VNTR) is a short sequence of DNA that is repeated at a specific chromosomal locus. The number of tandem repeated units vary between individuals; therefore, every human being’s unique sequence of base pairs can be used for personal or parental identification (The Biology Project 1996).
In this experiment, we extracted DNA from our cheek cells to detect our individual VNTR. Our objective was to find out our approximate repeat numbers on Chromosome 1 and to see if we are homozygous or heterozygous. Homozygous is when one receives a different number of chromosomes from his or her mother and father, and homozygous is when one receives the same number of chromosomes from his or her mother and father. I expected that I would be heterozygous, since according to the lab manual, there is an 80% chance of having different numbers of repeats on both chromosomes, which is much higher than a 20% chance of being homozygous. MATERIALS AND METHODS
In this experiment, we extracted DNA from cheek cells, loaded PCR products in a 1% agarose gel and took gel images. When loading our mixtures into the wells on the gel, we worked with positive and negative controls. The negative controls consisted of water and the positive controls consisted of purchased human DNA. The last two tubes consisted of buccal DNA. Please see lab manual for specific details.
My DNA band sizes were estimated from the standard DNA ladder lane, from which all the band sizes were known and the distances traveled for both the standard DNA ladder lane and my DNA bands were measured (Table 2). The standard curve helped estimate the corresponding base pairs DNA of my DNA bands from the...
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