Title Biotechnology-Principles-and-Processes.pdf ✅

3. Biotechnology: Principles and Processes Previous Year’s Question Genetic engineering is possible, because (1) we can cut DNA at specific sites by endonucleases like DNase (2) restriction endonucleases purified from bacteria can be used in-vitro (3) the phenomenon of transduction in bacteria is well understood (4) we can see DNA by electron microscope. CONSTRUCTION OF FIRST ARTIFICIAL RECOMBINANT DNA MOLECULE y Plasmids are extra-chromosomal material present in the bacteria. It can be physically separated and can replicate independently of the bacterial chromosome. It provides resistance to the bacteria against certain antibiotics. y First Artificial Recombinant DNA Molecule was constructed by Stanley Cohen and Herbert Boyer in 1972. y Stanley Cohen and Herbert Boyer in 1972 isolated antibiotic resistant gene by cutting a fragment of DNA from a plasmid. This antibiotic resistant gene fragment was then integrated with the plasmid DNA. y They cut the gene of antibiotic resistance from a plasmid with the help of a restriction enzyme and joined it to the plasmid of Salmonella typhimurium with the help of DNA ligase. y This newly formed DNA having fragments of antibiotic resistance is known as the recombinant DNA. y The plasmid of Salmonella typhimurium with the gene of antibiotic resistance acts as a vector and is transferred into the bacterium Escherichia coli . Definition Plasmid: Autonomously replicating extra-chromosomal material present in the bacteria that provides antibiotic resistance to the bacteria.