Question

If a PCR reaction is carried out 30 times, how much can the DNA sequence increase?

• A. 2 million times
• B. 2 billion times
• C. 2 trillion times
• D. 2 quadrillion times

Hint:

Remember, each cycle of PCR doubles the amount of DNA, and the number of DNA copies increases exponentially with each cycle.

Answer 1

The Correct Option is B

Step 1: Understanding PCR amplification.
Each cycle of PCR doubles the amount of DNA. After 30 cycles, the amount of DNA increases by a factor of \(2^{30}\), which is approximately 1 billion times.

Step 2: Analyzing the Options.
(A) 2 million times: This is too low — after 30 cycles, the increase is far higher than this.
(B) 2 billion times: Correct — \(2^{30} \approx 1 \text{ billion}\), so the DNA sequence is amplified by approximately 2 billion times after 30 cycles.
(C) 2 trillion times: This is too high for 30 cycles.
(D) 2 quadrillion times: This is much too high for 30 cycles.

Step 3: Conclusion.
The correct answer is (B) 2 billion times, as this is the approximate increase in DNA quantity after 30 cycles of PCR.