Question

How many copies of the DNA samples are produced in the PCR technique after 6-cycles.
(a) 4
(b) 32
(c) 64
(d) 16

Answer 1

Hint: It is a technique to make many copies of a specific DNA region in vitro. During this technique, the reaction is repeatedly cycled through a progression of temperature changes, which permit numerous copies of the target area to be produced.

Complete answer
The polymerase chain reaction (PCR) is a technique that exponentially amplifies a single copy of a particular DNA segment. It produces a large number of copies of that particular DNA segment. After the completion of one cycle, 2 copies are formed by a single DNA segment. After that, the completion of the second cycle, ${ 2 }^{ 2 }$ = 4 copies are produced. Similarly, after the nth cycle, ${ 2 }^{ 2 }$ copies are produced, where n is the number of cycles. Hence, after completion of the 6 cycles, ${ 2 }^{ 6 }$ = 64 copies will be produced.

Additional information
The basic steps of PCR are:
Step 1-Denaturation (${ 96 }^{ o }$C): It is the process in which heat the reaction strongly to separate, or denature, the DNA strands. This gives a single-stranded template for the next step.
Step 2-Annealing (${ 55 }^{ o }$-${ 65 }^{ o }$C): Cool the reaction so the primers can bind to their complementary sequences on the single-stranded template DNA.
Step 3-The extension (${ 72 }^{ o }$): In this process, the reaction temperatures will increase so Taq polymerase extends the primers, synthesizing new strands of DNA.

So, the correct answer is ‘64’.

Note:
Uses of PCR: In many research labs, PCR is used, and it also has practical applications in forensics, genetic testing, and diagnostics.
PCR is utilized to amplify genes associated with genetic disorders from the DNA of patients (or from fetal DNA, in the case of prenatal testing).
PCR can likewise be utilized to test for a bacterium or DNA virus in a patient's body: if the pathogen is present, it might be possible to amplify regions of its DNA from a blood or tissue sample.