Question

Write a case you can use PCR to solve the problem and also write a case you cannot use PCR to solve to problem

Answer 1

PCR is polymerase chain reaction used amplify gene of interest. In order to solve crime cases, an allele is chosen which is amplified to look for differences between the samples of the crime scene and that of the suspects. This is usually done when the allele varies in size because of repeats in different individuals. This is known as Short Tandem Repeat (STR) which is used to compare allele repeats at specific loci in DNA between two or more samples. The PCR product is run on gel to compare the size of bands. More the repeats, more is the size of DNA and less it travels from the well of the gel. This is an example where PCR can be used to solve the problem.

AN example where PCR cannot be used to solve a problem is in case of single-nucleotide polymorphism (SNP) which is a DNA sequence variation that occurs at a single nucleotide adenine (A), thymine (T), cytosine (C), or guanine (G). This cannot be distinguished on a gel after running the PCR product because SNP does not lead to different sized band.