Question

A scientist begins a PCR with 10 picograms of DNA and allows it to go through three cycles.

How much DNA, in picograms, does the scientist have at the end of three cycles?
a. 10 b. 80 c.40 d.20

Answer 1

b. 80g

Step-by-step explanation:

Three cycles of PCR would produce 3 doublings of the amount of DNA.

Cycle 1: 10x2 = 20pg

Cycle 2: 20x2 = 40pg

Cycle 3: 40x2 = 80pg

This can also be worked out for large cycle numbers by final mass = starting mass x 2ⁿ, where n is the number of cycles.