Biology · Biotechnology: Principles and Processes · NEET
No. This is the most common NEET trap. PCR only works on nucleic acids (DNA). It amplifies DNA in vitro, so all its uses are DNA-based: gene amplification, molecular diagnosis, and detection of gene mutations. Purifying an already-made protein is a downstream processing / separation step, not a PCR job. So 'purification of isolated protein' is NOT an application of PCR.
DNA fingerprinting needs enough DNA to analyse, but a crime scene may leave only a tiny amount. PCR amplifies (copies) that tiny sample many times. NCERT states the sensitivity of DNA fingerprinting was increased using PCR, so now DNA from even a single cell is enough to run the analysis.
PCR amplifies the target region so there is enough DNA to study. Once you have many copies, you can compare or sequence them to see if a base has changed. The amplification (making copies) is the PCR step; detecting the mutation is what you do with those copies. NEET treats 'detection of gene mutation' as a valid application of PCR.
It means making many identical copies of one specific DNA segment. In recombinant DNA technology, after you cut out the desired gene, you use PCR to multiply it (up to about a billion copies) so there is plenty of it to insert into a vector and clone. NCERT lists this as a step in rDNA technology.
No. PCR copies DNA quickly in a test tube (in vitro) using primers and Taq polymerase. Gene cloning inserts a gene into a vector and multiplies it inside a living host cell. They are often used together: PCR first amplifies the gene, then the amplified gene is cloned. For NEET, remember PCR = in vitro amplification, cloning = copies made inside a host.
Which of the following is not an application of PCR (Polymerase Chain Reaction)?
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Gene amplification (making many copies of a DNA segment), molecular diagnosis of diseases, detection of gene mutations, amplifying the gene of interest in recombinant DNA technology, and increasing the sensitivity of DNA fingerprinting so a single cell is enough.
Yes. Repeated cycles double the DNA each time (2 to the power n). NCERT notes the DNA segment can be amplified to approximately a billion copies, which is about 2 to the power 30.
PCR works only on DNA. It cannot copy or purify proteins. Protein purification belongs to downstream processing, a separate step in obtaining the foreign gene product.
Taq polymerase, a thermostable DNA polymerase isolated from the bacterium Thermus aquaticus. It stays active through the high-temperature denaturation step, so the same enzyme can run all the cycles.
PCR is done in vitro, meaning in a test tube outside a living cell. This is a key point NEET may test to separate PCR from in vivo cloning inside a host.
