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BIOTECHNOLOGY AND ITS APPLICATIONS., , Insulin used for diabetes was earlier extracted from, pancreas of slaughtered cattle and pigs. Insulin from an Proinsulin, animal source, though caused some patients to develop, allergy or other types of reactions to the foreign, , , , protein. Insulin consists of two short polypeptide g Avwentid, chains: chain A and chain B, that are linked together by 52 Pepive, disulphide bridges (Figure 12.3). In mammals, including 8 : Insulin, , humans, insulin is synthesised as a pro-hormone (like a, pro-enzyme, the pro-hormone also needs to be processed, before it becomes a fully mature and functional hormone) Free C peptide, , which contains an extra stretch called the C peptide., , This C peptide is not present in the mature insulin and is Figure 12.3 Maturation of, removed during maturation into insulin.The main pro-insulin into insulin, challenge for production of insulin using rDNA techniques (simplified), , was getting insulin assembled into a mature form. In, , 1983, Eli Lilly an American company prepared two DNA sequences, , corresponding to A and B, chains of human insulin and introduced them, , in plasmids of E. coli to produce insulin chains. Chains A and B;were, , produced separately, extracted and combined by creating disulfidébonds, , to form human insulin. ., , L If a person is born with a hereditary disease»ean a(Corrective therapy, , be taken for such a disease? Gene therapy is an‘attempt to do this., Gene therapy is a collection of methods that allows correction of a, gene defect that has been diagnosed in aychild/embryo. Here genes, are inserted into a person’s cells and™tissues to treat a disease., Correction of a genetic defect involves‘delivery of a normal gene into, the individual or embryo to take overthe function of and compensate, for the non-functional gene. :, , The first clinical gene therapy was given in 1990 to a 4-year old girl, with adenosine deaminase (ADA) deficiency. This enzyme is crucial for, the immune system to function. The disorder is caused due to the deletion, of the gene for adenosine deaminase. In some children ADA deficiency, can be cured by bone marrow transplantation; in others it can be treated, by enzyme replacement therapy, in which functional ADA is given to the, patient by injection. But the problem with both of these approaches that, they are not completely curative. As a first step towards gene therapy,, lymphocytes from the blood of the patient are grown in a culture outside, the body. A functional ADA cDNA (using a retroviral vector) is then, introduced into these lymphocytes, which are subsequently returned to —, the patient. However, as these cells are not immortal, the patient requires, periodic infusion of such genetically engineered lymphocytes. However, if, the gene isolate from marrow cells producing ADA is introduced into cells, at early embryonic stages, it could be a permanent cure., , + B peptide, , 2020-21
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212, , BIOLOGY, , 12.2.3 Molecular Diagnosis, , You know that for effective treatment of a disease, early diagnosis and, understanding its pathophysiology is very important. Using conventional, methods of diagnosis (serum and urine analysis, etc.) early detection is, not possible. Recombinant DNA technology, Polymerase Chain Reaction, (PCR) and Enzyme Linked Immuno-sorbent Assay (ELISA) are some of, the techniques that serve the purpose of early diagnosis., , Presence of a pathogen (bacteria, viruses, etc.) is normally suspected, only when the pathogen has produced a disease symptom. By this time, the concentration of pathogen is already very high in the body. However,, very low concentration of a bacteria or virus (at a time when the symptoms, of the disease are not yet visible) can be detected by amplification of their, nucleic acid by PCR. Can you explain how PCR can detect very low, amounts of DNA? 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., , A single stranded DNA or RNA, tagged with a radioactive molecule, (probe) is allowed to hybridise to its:complementary DNA in a clone of, cells followed by detectionusing autoradiography. The clone having the, mutated gene will hence notappear on the photographic film, because, the probe will not havecomplementarity with the mutated gene., , ELISA is baséd on the principle of antigen-antibody interaction., Infection by-pathogen can be detected by the presence of antigens, (proteins, glycoproteins, etc.) or by detecting the antibodies synthesised, against the pathogen., , 12.3 TRaNSGENIC ANIMALS, , Animals.that have had their DNA manipulated to possess and express an, extra (foreign) gene are known as transgenic animals. Transgenic rats,, rabbits, pigs, sheep, cows and fish have been produced, although over, 95 per cent of all existing transgenic animals are mice. Why are these, animals being produced? How can man benefit from such modifications?, Let us try and explore some of the common reasons:, , @) Normal physiology and development: Transgenic animals can, be specifically designed to allow the study of how genes are, regulated, and how they affect the normal functions of the body, and its development, e.g., study of complex factors involved in growth, such as insulin-like growth factor. By introducing genes from other, species that alter the formation of this factor and studying the, biological effects that result, information is obtained about the, biological role of the factor in the body., , (ii) Study of disease: Many transgenic animals are designed to increase, our understanding of how genes contribute to the development of, , 2020-21
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BIOTECHNOLOGY AND ITS APPLICATIONS., , disease. These are specially made to serve as models for human, diseases so that investigation of new treatments for diseases is made, possible. Today transgenic models exist for many human diseases, such as cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer’s., , (iii) Biological products: Medicines required to treat certain human, diseases can contain biological products, but such products are, often expensive to make. Transgenic animals that produce useful, biological products can be created by the introduction of the portion, of DNA (or genes) which codes for a particular product such as, human protein (c-1-antitrypsin) used to treat emphysema. Similar, attempts are being made for treatment of phenylketonuria (PKU), and cystic fibrosis. In 1997, the first transgenic cow, Rosie, produced, human protein-enriched milk (2.4 grams per litre). The milk, contained the human alpha-lactalbumin and was nutritionally a, more balanced product for human babies than natural cow-milk., , (iv) Vaccine safety: Transgenic mice are being developed for use in, testing the safety of vaccines before they are used on humans., Transgenic mice are being used to test the safety of the polio vaccine., If successful and found to be reliable, they could replace thé use of, monkeys to test the safety of batches of the vaccine., , () Chemical safety testing: This is know a toxicity/safety testing., The procedure is the same as that usedfor testing toxicity of drugs., Transgenic animals are made that carry geneswhich make them more, sensitive to toxic substances than ‘non-transgenic animals. They are, then exposed to the toxic substances and the effects studied. Toxicity, testing in such animals will allow uso obtain results in less time., , 12.4 Eruicat Issues, , The manipulation of living organisms by the human race cannot go on, any further, without regulation. Some ethical standards are required to, evaluate the morality of all human activities that might help or harm living, organisms., , Going beyond the morality of such issues, the biological significance, of such things is also important. Genetic modification of organisms can, have unpredicatable results when such organisms are introduced into, the ecosystem., , Therefore, the Indian Government has set up organisations such as, GEAC (Genetic Engineering Approval Committee), which will make, decisions regarding the validity of GM research and the safety of, introducing GM-organisms for public services., , The modification/usage of living organisms for public services (as food, and medicine sources, for example) has also created problems with patents, granted for the same., , 2020-21, , \W, , (L
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BIOLOGY, , , , There is growing public anger that certain companies are being, granted patents for products and technologies that make use of the, genetic materials, plants and other biological resources that have long, been identified, developed and used by farmers and indigenous people, of a specific region/country., , Rice is an important food grain, the presence of which goes back, thousands of years in Asia's agricultural history. There are an estimated, 200,000 varieties of rice in India alone. The diversity of rice in India is, one of the richest in the world. Basmati rice is distinct for its unique, aroma and flavour and 27 documented varieties of Basmati are grown, in India. There is reference to Basmati in ancient texts, folklore and, poetry, as it has been grown for centuries. In 1997, an American, company got patent rights on Basmati rice through the US Patent and, Trademark Office. This allowed the company to sell a ‘new’ variety of, Basmati, in the US and abroad. This ‘new’ variety of Basmati had actually, been derived from Indian farmer's varieties. Indian Basmati was crossed, with semi-dwarf varieties and claimed as an invention or a novelty. The, patent extends to functional equivalents, implying that other people, selling Basmati rice could be restrieted“by the patent. Several attempts, have also been made to-patent_ uses; products and processes based on, Indian traditional herbal’medicines, e.g., turmeric neem. If we are not, vigilant and we do*nhotimmediately counter these patent applications,, other countries /individuals’may encash on our rich legacy and we may, not be able todo anything about it., , Biopiracy is the’term used to refer to the use of bio-resources by, multinational companies and other organisations without proper, authorisation from the countries and people concerned without, compensatory payment., , Most of the industrialised nations are rich financially but poor in, biodiversity and traditional knowledge. In contrast the developing and, the underdeveloped world is rich in biodiversity and traditional, knowledge related to bio-resources. Traditional knowledge related to, bio-resources can be exploited to develop modern applications and can, also be used to save time, effort and expenditure during their, commercialisation., , There has been growing realisation of the injustice, inadequate, compensation and benefit sharing between developed and developing, countries. Therefore, some nations are developing laws to prevent such, unauthorised exploitation of their bio-resources and traditional, knowledge., , The Indian Parliament has recently cleared the second amendment, of the Indian Patents Bill, that takes such issues into consideration,, including patent terms emergency provisions and research and, development initiative., , SS, , 2020-21
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BIOTECHNOLOGY AND ITS APPLICATIONS., , , , , , , , , , SUMMARY, , Biotechnology has given to humans several useful products by using, microbes, plant, animals and their metabolic machinery. Recombinant, DNA technology has made it possible to engineer microbes, plants, and animals such that they have novel capabilities. Genetically, Modified Organisms have been created by using methods other than, natural methods to transfer one or more genes from one organism to, another, generally using techniques such as recombinant DNA, technology., , GM plants have been useful in increasing crop yields, reduce postharvest losses and make crops more tolerant of stresses. There are, several GM crop plants with improved nutritional value of foods and, reduced the reliance on chemical pesticides (pest-resistant crops)., , Recombinant DNA technological processes have made immense, impact in the area of healthcare by enabling mass production of safe, and more effective therapeutics. Since the recombinant therapeutics, are identical to human proteins, they do not induce unwanted, immunological responses and are free from risk of infection as was, observed in case of similar products isolated from non-human sources., Human insulin is made in bacteria yet its structure is abso] ly, identical to that of the natural molecule. 4 N, , Transgenic animals are also used to underétand how genes, contribute to the development of a disease by sétving as, human diseases, such as cancer, cystic soos oad arthritis, and Alzheimer's., , Gene therapy is the insertion of eae ey, and tissues to treat diseases especially Heredit Ty ‘diseases. It does, so by replacing a defective mutant allele galt ‘a functional one or, gene targeting which involves gene amplific mn. Viruses that attack, their hosts and introduce their genetic material into the host cell as, part of their replication cycle are used as vectors to transfer healthy, genes or more recently portions of genes., , The current interest in the manipulation of microbes, plants, and, animals has raised serious ethical” questions., , , , , , , , , , , , , , , , 2., 3., , EXERCISES, , Crystals of Bt toxin produced by some bacteria do not kill the bacteria, themselves because —, , (a) bacteria are resistant to the toxin, , (b) toxin is immature;, , (c) toxin is inactive;, , (d) bacteria encloses toxin in a special sac., , What are transgenic bacteria? Illustrate using any one example., , Compare and contrast the advantages and disadvantages of production, of genetically modified crops., , 2020-21, , \W, , , , NIJIWI
