This animation describes PCR, a standard laboratory technique for making many copies of a specific DNA sequence.

Polymerase chain reaction, or PCR, amplifies specific sequences of DNA with the help of primers, short sequences that are complementary to two regions flanking the target DNA. As shown in the animation, DNA is repeatedly heated and cooled in the presence of the primers and the enzyme Taq polymerase. In as few as 30 cycles, a billion copies of the target sequence can be made.

Depending on students’ background, it may be helpful to pause the animation at various points to discuss different steps in the PCR method.