Genetic Differences Of Mitochondrial DNA

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Introduction When observing a human population there are many phenotypical differences such as; behavior, development, and morphology. Not only are there phenotypical differences amongst a human population, but there are also genotypic differences that can be observed using DNA sequencing data. One way to observe genetic variation amongst humans would be to sequence the Mitochondrial DNA(mtDNA). Mitochondrial DNA is the most commonly used DNA to form phylogenetic trees. Human Mitochondrial DNA is about 16,500 bps in size and consists of 13 protein coding genes, 22 tRNAs (transfer RNA), and 2 rRNAs (ribosomal RNA) (Ingman, 2001). Mitochondrial DNA has many beneficial uses for DNA sequencing such as; its ability to be extracted from small …show more content…
From the extracted DNA, students amplified the HV1 control region of the mtDNA using Polymerase Chain Reaction (PCR). PCR is the process of heating and cooling DNA strands to produce millions of DNA copies from a single strand. PCR products were checked using gel electrophoresis, the process of separating DNA fragments, and then sent for DNA sequencing. The sequenced DNA was compared to a reference sequence which allowed students to determine their maternal haplotypes based on polymorphisms, or variations in genes, DNA, and chromosomes. The methods briefly introduced above were used to prove that an individual’s polymorphisms will match the haplogroup associated with his/her mother’s …show more content…
First, students swabbed the inside of their cheek for at least 30 seconds with a cotton swab to obtain their sample for DNA extraction. 180 µl of Buffer ATL and 20 µl of proteinase K were added to the swabbed sample using sterile micropipetting techniques. The swabbed samples were incubated at 56 ⁰C in a hot block. Next, students isolated their HV1 control region DNA through a series of washes which contained 200µl of Buffer ATL, 200µl of ethanol, 500 µl of Buffer AW1 and AW2, and 50 µl of Buffer AE (Penn State Biology 220W Lab Manual, pgs. 48-49) After completing a series of washes, students quantified the amount of DNA in their sample using the NanoVue Spectrophotometer. Using their results from the NanoVue, students were able to determine the amount of their sample DNA and PCR master mix they needed to add to PCR tubes. Then, the samples were loaded into the PCR machine to amplify DNA samples. Once the PCR cycle was complete, samples were stored in a freezer at -20⁰C. With the products from PCR, students used Gel Electrophoresis to separate electrically charged molecules. Gel Electrophoresis requires 3 steps; preparing a gel solution, gel electrophoresis, and photographing the gel. To prepare the gel, students mixed .3g of agarose and 30mLs of 1X TAE buffer in a 125 ml flask (Penn State Biology 220W Lab Manual,

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