What is the function of the structure shown in the diagram

c.) polymerase chain reaction

- "unlike the original dna fingerprinting method, dna profiling does not use restriction enzymes to cut the dna. instead it uses the polymerase chain reaction (pcr)? to produce many copies of specific str sequences. pcr is an automated procedure that generates lots of copies of a specific sequence of dna."

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.