Describe the steps in the polymerase chain reaction (PCR).

There are three steps in PCR. The first step is denaturation. A solution of DNA is heated to 90 to 100C for a few minutes to break the hydrogen bonds between the two polynucleotide strands, producing two single-stranded molecules that will serve as templates. The second step is hybridization. The DNA solution is rapidly cooled to about 50C, and primers for DNA replication bind to complementary regions on the single-stranded DNA fragments, marking the boundaries of the region to be copied. The third step is DNA synthesis. After the primers are bound to the template strands, the enzyme Taq polymerase (a DNA polymerase from a bacterial species found in hot springs) synthesizes a complementary DNA strand beginning at the primers.