Answer:
To determine the number of PCR rounds required to amplify 0.2ng of a DNA fragment to 1mg, we need to calculate the fold amplification achieved in each PCR cycle and then determine the number of cycles needed to reach the desired 1 million-fold amplification.
In each PCR cycle, the amount of DNA doubles. Therefore, the fold amplification achieved in each cycle is 2.
We can use the following formula to calculate the fold amplification after 'n' PCR cycles:
Fold amplification = 2^n
We need to find the value of 'n' that satisfies the following equation:
0.2ng * (2^n) = 1mg
Converting the units to the same base, we have:
0.2ng * (10^6) * (2^n) = 1g
Simplifying:
0.2 * 10^6 * 2^n = 1 * 10^9
2^n = 1 * 10^9 / (0.2 * 10^6)
2^n = 5 * 10^3
Taking the logarithm of both sides:
n * log(2) = log(5 * 10^3)
n = log(5 * 10^3) / log(2)
Using a calculator:
n ≈ 12.29
Since 'n' represents the number of PCR cycles, we round up to the nearest whole number. Therefore, approximately 13 rounds of PCR are required to amplify 0.2ng of the DNA fragment to 1mg.
Among the given options, the closest number of rounds to 13 is:
11 or 12 rounds of PCR.
Therefore, the answer is either 11 or 12 rounds of PCR.
Step-by-step explanation: