In PCR, what are the short single-stranded DNA fragments that match a gene of interest called?

In the context of PCR (Polymerase Chain Reaction), the short single-stranded DNA fragments that are designed to match specific sequences of the gene of interest are known as primers. Primers serve as the starting point for DNA synthesis because they provide a free 3' hydroxyl (OH) group for DNA polymerase to extend the new DNA strand.

Primers are crucial because they define the region of the target DNA that will be amplified. Each PCR reaction typically includes two primers: one for each strand of the DNA template. By binding to complementary sequences on the target DNA, they ensure that the amplification process is specific to the desired gene.

While oligonucleotides can refer to short DNA or RNA molecules, in PCR, the term specifically indicates primers when discussing the fragments that bind to the target sequences. Templates refer to the original DNA strand that contains the sequence of interest from which new strands are built. Amplifiers is not a term commonly used to describe any components of PCR; it does not specifically refer to any material involved in the amplification process. This contextual understanding reinforces why primers are the correct answer.