Biotechnology: Principles and Processes
Read the following passage carefully and answer the given questions.
Biotechnology deals with large scale production and marketing of products and processes using live organisms, cells or enzymes. 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. This process involves the use of restriction endonucleases, DNA ligase, appropriate plasmid or viral vectors to isolate and ferry the foreign DNA into host organisms, expression of the foreign gene, purification of the gene product, i.e., the functional protein and finally making a suitable formulation for marketing. Restriction endonucleases are used in genetic engineering to form ‘recombinant’ molecules of DNA, which are composed of DNA from different sources (genomes). 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.
Identify the microorganism used for the construction of the first recombinant DNA.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Salmonella typhimurium
The first recombinant DNA was made by linking a gene for antibiotic resistance to a native plasmid of one bacterium. Stanley Cohen and Herbert Boyer did this in 1972.
(1) Salmonella typhimurium — Correct. The plasmid used belonged to this bacterium.
(2) Escherichia coli — Incorrect. It is the host that is commonly used to grow recombinant DNA. The restriction enzyme EcoRI is named after it. It did not give the plasmid of the first recombinant DNA.
(3) Agrobacterium tumefaciens — Incorrect. It is a plant pathogen whose Ti plasmid is used as a vector for plants.
(4) Retrovirus — Incorrect. Disarmed retroviruses are used as vectors to carry genes into animal cells. They are not bacteria and have no plasmid.
Note: This passage is taken from NCERT as it is. 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 – …
