According to the AHDI, the dates in the sign-off block are usually:

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."

it is a limiting nutrient limited by a single nutrient in the ecosystem, & the single goes very slow.

dna is a set of a gene held together by a chemical bond