Eli5: how does a PCR test work?

Question

Eli5: how does a PCR test work?

In: Chemistry

Answer 1

You start with a forward and reverse primer that match up with the two sides of the section of DNA that you are interested in. You mix that with some other chemicals and the DNA. That mixture is put on a thermal cycler; an instrument that raises and lowers the temperature of your reaction. At a high temperature, the DNA splits from double stranded to single stranded. As the reaction cools, the primers attach and start making a complimentary strand of DNA with the nucleotides (building blocks of DNA) that are part of the reaction mix to form a new double stranded section out of each single strand. You have now doubled the amount of the section if DNA that you are interested in. This cycle repeats (usually 35-40 times). Every cycle you are doubling the amount of double stranded DNA that you had from the previous cycle. You end up turning one DNA strand into millions of DNA strands.

There is a lot more complexity, but that is the basic idea.