PCR
Read the following passage carefully and answer the given questions.
In PCR multiple copies of the gene of interest is synthesised in vitro using two sets of primers and the enzyme DNA polymerase. The enzyme extends the primers using the nucleotides provided in the reaction and the genomic DNA as template. If the process of replication of DNA is repeated many times, the segment of DNA can be amplified to approximately billion times, i.e., 1 billion copies are made. Such repeated amplification is achieved by the use of a thermostable DNA polymerase, which remain active during the high temperature induced denaturation of double stranded DNA. The amplified fragment if desired can now be used to ligate with a vector for further cloning.
PCR is not used in:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Bone marrow transplantation
PCR makes a very large number of copies of a chosen piece of DNA. It is used wherever a small amount of DNA has to be detected or multiplied.
(1) Detection of mutations in cancer patient — A use of PCR. It is used to detect mutations in genes in suspected cancer patients.
(2) Identification of genetic disorders — A use of PCR. It helps to identify many genetic disorders.
(3) Bone marrow transplantation — Not a use of PCR. This is a treatment in which blood-forming cells are placed in a patient. PCR is a tool that copies and detects DNA, and NCERT does not list it for transplantation.
(4) Amplification of genes for cloning — A use of PCR. The amplified fragment can be joined to a vector for further cloning.
Note 1: This question belongs to the chapter Biotechnology and its Applications (molecular diagnosis). It has been tagged with the rest of the passage under Biotechnology: Principles and Processes.
Note 2: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.
NCERT Extract:
Molecular Diagnosis – “… PCR is now routinely used to detect HIV in suspected AIDS patients. It is being used to detect mutations in genes in suspected cancer patients too. It is a powerful techqnique to identify many other genetic disorders.”