Polymerase Chain Reaction
I swabbed my cheeks to procure a sample of my DNA. This sample was then sent to be tested by Family Tree DNA. The first step in DNA analysis is Polymerase Chain Reaction (PCR) which amplifies a specific target sequence or sequences chosen by the scientists to be analyzed. The DNA is first denatured using heat to break hydrogen bonds so that the two strands of the double helix molecule separate. Then, as the temperatures are lowered the annealing process begins. The primers that were created by the scientists to be complementary to the beginning and end segments of the target sequence would bond to both strands of the sample DNA. Added nitrogenous bases would then bind to their complementary bases on the sample DNA strands. The entire process would be repeated until there are (Hundreds? Thousands?) of copies of the target sequence or sequences.
DNA Analysis
Exceeding Your Expectations
DNA Sequencing
To sequence DNA, DNA polymerase copies short strands of the DNA sample. As the DNA is copied, special nucleotides are randomly added to the DNA strand. Once one of these special nucleotides is added to a DNA strand, the DNA polymerase stops copying. This process happens millions of times until there are millions of different sized DNA strands. Mathematically this results in the existence of strands of every possible length of nucleotides in the strand of DNA. By looking at the ends of each different strand and the lengths of each different strand, the order of the nucleotides in the DNA sample strand can be determined.
Gel Electrophoresis
Gel electrophoresis is the process of running an electric current to a porous gel with DNA placed on the side of the negatively charged electrode. Since DNA is negatively charged, when the electric current is applied, the DNA will move towards the positive charged electrode. The larger the strand of DNA, the less it will move towards the positive electrode. The image depicts the gel electrophoresis of the strand of DNA that was sequenced in the picture above. The colors correspond to different nitrogenous bases that correspond with the DNA that was sequenced in the image above. The green bar closest to the negative electrode represents the last nucleotide on this strand of DNA since it is the last nucleotide on the longest strand of DNA analyzed by the gel electrophoresis.