The technology involves combining DNA from two different organisms to generate a recombinant. This DNA involves manip0ulation or engineering of two DNA involved and therefore the term “genetic engineering” has come into being. This is otherwise known as “recombinant DNA technology”.
Two main discoveries to the birth of this field of research are first is the discovery of restriction enzymes elaborated mostly by certain bacteria. Restriction enzymes are endonucleases which cut DNA at specific sites in fragments containing identifiable genes. The second break through is because of the development of methodologies to produce large quantities of these DNA fragments containing genes using vectors or cloning vehicles.
Techniques of genetic engineering: Various steps in recombinant technology are as follows.
At the first step, DNA molecules are cut into specific fragment containing identifiable genes by using restriction enzyme endonuclease.
Vectors are used for transferring the DNA fragment to a suitable recipient bacterium. Vectors may be plasmids, bacteriophages (viruses), cosmids and others. A vector facilitates the manipulation and recognition of newly created recombinant molecule.
The restriction endonuclease used to cut the foreign DNA is also used to splica the plasmid at specific point in such a manner so as to have stickly ends in both the molecules.
The free sticklly ends of the plasmid DNA and the foreign DNA serve as convenient points for their complementary pairing.
The gaps are then sealed by an enzyme ligase, thus making a circular DNA piece which contains the plasmid genes as well as a piece of foreign DNA. The product is referred to as recombinant DNA.
Within the bacterial cell, the recombinant DNA molecule is replicated along with endogenous DNA of host cell during asexual reproduction, a process referred to as cloning.
The cloned recombinant DNA produced in abundance in an overnight bacterial culture is isolated purified and analyzed.
The foreign DNA can then be released from the recombinant plasmid of clone cells once again by the use of restriction enzymes. Thus large quantities of foreign genes can be isolated by this technology. Protentially cloned DNA can be transcribed its m-RNA, translated and the gene product is isolated and studied.
Application of biotechnology:
Foods: The preparation of important food can be possible by employing micro-organisms. These food items are bread, dosa, sauce etc. diary products include yoghurt, curd, these, butter etc. their preparation depends on scientific strains of micro organisms.
Alcoholic beverages: For the preparation of bear, wines whisky etc.
Non-alcoholic beverages are produced by curing of coffee bears and tea leaves by fermentation due to microbial action.
Sewage treatment: Different types of bacteria, fungi and algae also take part in the removal of organic matter in the sewage.
Biogas (Gobar gas): It is produced by fermentation of cow dung, farm refuge garbage etc.
Bio-fertilizers: These are nitrogen fixing micro-organisms which are found either in soil or associated with plants. The bio-fertilizers are likely to reduce the need of chemical fertilizers.
Organic acids like lactic, gluconic, acetic and citric acid are obtained by biotechnology.
Enzymes: Enzymes required for industrial and medicinal use are available for microbial processes.
Vitamins: Some vitamins like B2, B12, are products of micro-organisms.
Antibiotics: A number of antibiotics are derived from the fermentation of organic compounds.
Hormones: Insulin, growth hormone and other hormones are mostly synthesized through the use of microbes and genetic engineering.
Vaccines: Vaccines are used for providing immunity against important diseases. Vaccines contain modified or inactivated or killed pathogens or their antigens.
Steroids: These are derivatives of fats and are commonly used as antifertility formulation.
Monoclonal antibodies: Antibodies against pathogen can be obtained from clonal cultures of microbes.
Tissue culture: These methods are being used for the improvement of agriculture, forestry, induction of mutations and resistance.
Transplants: Test tube babies and embryo transplant techniques are useful tools for rapid multiplication and production of genetically improved superior varieties.
Genetic engineering: It is also called rembinant DNA technology and brings about improvement of genetic make up of an organism.