Multiple Choice
A molecular biologist has isolated a short segment of DNA that she wants to replicate in vitro. First she heats the DNA, which separates the two strands, and then she adds __________.
18. Biotechnology
The Steps of PCR
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If you start with one double-stranded DNA molecule and you perform SIX cycles of PCR, how many double
stranded copies of the DNA will you have?
A
6.
B
8.
C
16.
D
32.
E
64.
Verified step by step guidance1
Understand the basic principle of PCR: PCR (Polymerase Chain Reaction) is a technique used to amplify DNA, meaning it makes many copies of a specific DNA segment. Each cycle of PCR doubles the number of DNA molecules.
Start with the initial number of DNA molecules: You begin with one double-stranded DNA molecule.
Calculate the number of DNA molecules after each cycle: Since each cycle doubles the number of DNA molecules, you can use the formula \(2^n\), where \(n\) is the number of cycles.
Apply the formula for six cycles: Substitute \(n = 6\) into the formula \(2^n\) to determine the number of double-stranded DNA molecules after six cycles.
Interpret the result: The calculation will show that after six cycles, the number of double-stranded DNA molecules is \(2^6\). This is how you determine the final number of DNA copies.
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