Question

Which of the following statements about PCR primers is true?

1. PCR primers are short fragments of RNA.
2. Primers will not be consumed in the PCR reaction.
3. PCR primers are incorporated into the PCR product.
4. Upstream and downstream primers are complementary to each other.

Answer 1

Statement 3 is true: PCR primers, which are short DNA fragments, are incorporated into the PCR product during the amplification process.

Step-by-step explanation:

The correct statement about PCR (Polymerase Chain Reaction) primers from the options provided is that PCR primers are incorporated into the PCR product. PCR primers are short fragments of DNA, not RNA, which are complementary to each end of the target sequence. Their primary function is to provide a starting point for DNA polymerization during the PCR process because DNA polymerase enzymes cannot start the synthesis from scratch and require a primer with a free 3'-hydroxyl group.

Primers are indeed consumed in the PCR reaction as they are integrated into the newly synthesized DNA strands. Each primer is specifically designed to be complementary to the target DNA sequence that needs to be amplified, but upstream and downstream primers are not complementary to each other; instead, they are complementary to opposing strands of the DNA being amplified. Therefore, the correct answer to the student's question is that PCR primers are incorporated into the PCR product.