Which statement is true regarding the ends of an oligonucleotide primer?

The statement regarding the ends of an oligonucleotide primer that accurately captures an important aspect of primer design is that both the 3' and 5' ends may serve as a template for Taq elongation.

In the context of PCR (Polymerase Chain Reaction) and DNA synthesis, the 3' end of the primer is vital because it is where DNA polymerase, like Taq, adds new nucleotides during elongation. The DNA polymerase requires a 3' hydroxyl group to initiate the addition of nucleotides; hence, the 3' end of the primer must be available for this function.

While the 5' end of the primer is essential for determining the binding and specificity of the primer to the target DNA, it does not serve as a substrate for elongation since no nucleotides can be added to the 5' end in the same manner as at the 3' end. Therefore, while the 5' end is indeed critical for specificity, this aspect does not extend to Taq elongation capability.

This nuanced understanding of primer structure and function is fundamental when designing oligonucleotides for amplification processes and highlights the distinct roles of each end of the primer in the