NEETZoologyBiotechnology - Principles and Processes
A student prepares a reaction mixture for Polymerase Chain Reaction (PCR) by mixing the template DNA, primers, deoxynucleotides, and a normal DNA polymerase isolated from human cells in a single tube. The tube is then subjected to the standard temperature cycles of PCR. What will be the expected outcome of this reaction?
Options
- AThe gene will be amplified normally, but the process will take a longer time.
- BThe primers will fail to bind to the complementary regions of the template DNA.
- CExactly one complete copy of the target DNA will be synthesised before the reaction stops.
- DNo amplification will occur because the enzyme will get denatured during the first heating step.
Correct answer
D. No amplification will occur because the enzyme will get denatured during the first heating step.
Step-by-step solution
In a standard Polymerase Chain Reaction (PCR), all components are mixed before the temperature cycles begin. The very first step of a PCR cycle is denaturation, which requires heating the reaction mixture to a high temperature to separate the double-stranded DNA. Normal DNA polymerase isolated from human cells is not thermostable and will be permanently denatured (destroyed) by this high heat. Because the enzyme is destroyed in the first step, it will not be able to extend the primers in the subsequent steps. As a