Final answer:
The short oligonucleotides used during PCR to amplify a specific region of DNA are known as primers, which are necessary for the DNA polymerase to start the replication process.
Step-by-step explanation:
The short oligonucleotides that flank the region of DNA to be amplified by PCR are called primers. A primer is a small DNA fragment, typically 10-20 bases long, that is chemically synthesized to be complementary to the base sequence of both template DNA strands at their 3'-ends. During PCR amplification, these primers anneal to the target DNA sequence, and DNA polymerase extends them to create new strands of DNA. The Taq polymerase, which originates from the thermally stable bacterium Thermus aquaticus, is often used for PCR because it can withstand the high temperatures needed during the reaction.