Principles and processes of biotechnology
Read the following passage carefully and answer the given questions.
The DNA fragments separate according to their size through sieving effect provided by the agarose gel. Vectors used at present, are engineered in such a way that they help easy linking of foreign DNA and selection of recombinants from non-recombinants. If we are able to link an alien piece of DNA with bacteriophage or plasmid DNA, we can multiply its numbers equal to the copy number of the plasmid or bacteriophage. In the year 1963, the two enzymes responsible for restricting the growth of bacteriophage in Escherichia coli were isolated. One of these added methyl groups to DNA, while the other cut DNA. The latter was called restriction endonuclease. The first restriction endonuclease - Hind II, whose functioning depended on a specific DNA nucleotide sequence was isolated and characterised five years later. In PCR reaction, multiple copies of the gene of interest are synthesised in vitro using two sets of primers (small chemically synthesised oligonucleotides that are complementary to the regions of DNA). Modern biotechnology using genetically modified organisms was made possible only when man learnt to alter the chemistry of DNA and construct recombinant DNA. This key process is called recombinant DNA technology or genetic engineering.
Which one of the following steps is not related to genetic modification of an organism?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Integration of the desired DNA into the host
There are three basic steps in genetically modifying an organism: identification of DNA with the desirable genes, introduction of the identified DNA into the host, and maintenance of the introduced DNA in the host with its transfer to the progeny.
(1) Identification of DNA with desirable genes — A step in genetic modification of an organism. This is the first step.
(2) Introduction of the identified DNA into the host — A step in genetic modification of an organism. This is the second step.
(3) Integration of the desired DNA into the host — Not a step in genetic modification of an organism. It is not one of the three steps. A vector such as a plasmid keeps copying itself inside the host, so the DNA does not have to be integrated into the host DNA.
(4) Maintenance of introduced DNA in the host — A step in genetic modification of an organism. This is the third step. The DNA has to stay and multiply in the host and be passed on to its progeny.
Note: 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:
Principles of Biotechnology – …
