A PCR reaction begins with one double-stranded segment of DNA. Ho...

Question

A PCR reaction begins with one double-stranded segment of DNA. How many double-stranded copies of DNA are present after the completion of 10 amplification cycles? After 20 cycles? After 30 cycles?

Accepted Answer

Welcome back, everybody. Here's our next question. The polymerase chain reaction is a process of amplifying a specific DNA template with a polymerase enzyme and a variety of primers supplemented with free nucleotides. If the number of double stranded DNA pieces is doubled in each cycle, how many cycles have to be completed to get 16 DNA strands? A two B, eight C four or D three. So we can think this through if we imagine that we start our PCR with one DNA strand, then after one cycle, it will double and we'll have two after another cycle that will double and that will be four, another cycle will get eight and another cycle will be 16. And so when we go back and count, that gives us 1234 cycles to get to 16 DNA strands. And so that's choice C, you can actually calculate this by using the formula two to the nth power where N is the number of cycles. And we'd say that the total number of strands equals two to the N. But again, to get to 16 DNA strands, we'd need to have completed choice C four cycles. See you in the next video.

A PCR reaction begins with one double-stranded segment of DNA. How many double-stranded copies of DNA are present after the completion of 10 amplification cycles? After 20 cycles? After 30 cycles?

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