So, exactly how do we get all those numbers from a cheek swab? Advances in DNA testing technology enable scientists to take a tiny a particle of DNA and turn it into a probability of paternity.
The lab puts the extracted DNA into a special solution containing primers, small man-made DNA fragments that can find and copy the DNA markers, along with enzymes used to build copies of the DNA.
PCR begins by separating the double-stranded DNA – simply by turning up the heat. As it cools, the primers find and stick to the parts of the DNA, making a copy. By the end of the first cycle a single bit of DNA is copied into two identical strands.
These steps, heating and cooling the DNA solution and copying the DNA strands, are repeated 28 times and make billions of copies of DNA fragments.The DNA pieces are colored with a fluorescent dye, so a computer can easily find and measure the copies.
