Question

You need to amplify a specific DNA sequence from a dried drop of blood at a crime scene. A forensic hematologist informs you that there are approximately 1000 white blood cells and 5000 red blood cells in this dried sample. She also confirms that the sample is human blood. The DNA sequence you choose to amplify occurs once per haploid genome. If you perform 30 cycles of amplification in a thermal cycler using Taq polymerase, how many copies of the DNA sequence will you have at the end of the amplification?

Answer 1

There is a simple formula for calculating the number of amplicons after a defined number of cycles of a thermocycler run.

That is 2ⁿ. where, n = number of cycles the ample was run

The DNA has been isolated from the blood sample and rum in thermoscycler for 30 cycles

So number of copies od the DNA sequence will be =2³⁰

which comes out to be : 1073741824, which is approximately 1.07 *10^{9 .} That is more than one billion copies of the DNA sequence will be obtained.