This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of nucleic acids, Subject name: Biochemistry
PCR requires 
Select and explain. 
A. Primer, B. DNA Polymerase, C. De-oxyribonucleotide phosphate, D. Di-oxyribonucleotide phosphate
A: Primer
Answer: A: Primer 
Explanation: A primer is a sho strand of RNA or DNA (generally about 18-22 bases) that serves as a staing point for DNA synthesisPolymerase chain reaction uses DNA primers because they are more temperature stable. In experiments, it is often impoant to use a primer with a similar Tm to the template strand it will be hybridizing to.Ref: DM Vasudevan, 7th edition, page no: 638