Question

When viewing a graph of a PCR reaction that shows the number of copies vs. the number of cycles, how many cycles does it take to get:

a) 10 copies

b) 100 copies

c) 1,000,000 copies

Answer 1

Ans- PCR is a rapid and versatile in vitro method for amplifying defined target sequence present within the source of DNA. This technique was formulated by kary mulis in 1985.

Essential components of PCRs is : thermostable DNA polymerase, primers, dNTP, divalent cations, buffer and template DNA.

Hence, after each cycle, the number of templates doubles, so that if one start with a single dsDNA molecule, after 20 cycles, the number of molecules synthesized by the PCR is 1000,000

When amplifying a small segment of a long double stranded DNA template, the desired blunt ended target fragments first appear in the third cycle of PCR.