To allow forensic scientists to use tiny amounts of DNA they find, such as droplets of hair or skin, the DNA is copied numerous amounts of times using the PCR. the process uses DNA primers which are short DNA sequences complementary to the DNA adjacent to the Short tandem repeat sequence. the primers are marked with fluorescent tags, and the sample is placed in a reaction tube with DNA polymerase, the primers and nucleotides. once in the machine, the tube undergoes a cycle of different temperatures. the first temperature seperates the double stranded DNA, the second optimises prime binding to the target DNA sequence , the polymerase attaches and replication occurs. the third temperature is the optimum temperature for the heat stable DNA polymerase.
as the cycle continues, huge numbers of the DNA fragments are reproduced.
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