genotyping

Genotyping is a common technique learned in the genetic lab used to figure out the genotype of animals form their DNA. A proper genotyping is done in three distinct steps. The first is DNA extraction, the second is PCR, and the third is gel electrophoresis. The first step is DNA extraction. This is typically done using silicon columns. In this method, the lysis buffer and proteinase k is added to the tissue and incubated. The tube is then spun so that the supernatant can be removed without contamination. When this is done, the supernatant is then put into a spin column. It is then spun. This allows for the DNA to bind to the silicon and the rest of the supernatant to be separated from the DNA. The column is then washed using a wash buffer to remove any impurities and the column is then put into a new collection tube and eluted. The eluted solution contains DNA. The DNA is then put into another tube, and buffer, forward primer, reverse primer, MgCl2, and taq Polymerase are added. This is then heated and cooled at the optimal temperature for the gene, allowing for the duplication of the desired DNA. The resulting solution is then put into a well of the gel, and the gel is then ran using electricity. The resulting gel is able to show whether the gene is present or not. However, every gene is different in how it shows in the gel. One of the things that can be done if there is a relatively large amount of soft tissue is to skip on DNA extraction and just boil the tissue at 95 degrees in NaOH, adding tris HCl after. This is a more crude way of extracting DNA however, it is effective in some tissues, such as mouse ear, and often saves time.