⚠️The text in this card is totally from NCERT and info from related chapters or tricks are also included in "Extra" Field that can be seen in the bottom of the card. The cards are bigger than usual, as it takes a lot of time and brain to make short cards so I made big cards for each topic instead of making many cards from each topic, it doesn't make any difference though.
This is a flash card deck for the chapter 'Biotechnology and its Applications' of Class 12th, based on the latest syllabus for NEET 2024. You can download other chapters by clicking on "The author has shared x other item(s)." below the title of this page.
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| Text | Animals that have had their DNA manipulated to possess and express an extra (foreign) gene are known as {{c1::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.(i) 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 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 (α-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 the use of monkeys to test the safety of batches of the vaccine.(v) Chemical safety testing: This is known as toxicity/safety testing. The procedure is the same as that used for testing toxicity of drugs. Transgenic animals are made that carry genes which 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 us to obtain results in less time. |
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| Text | Tissue culture was learnt by scientists, during 1950s, that whole plants could be regenerated from explants, i.e., any part of a plant taken out and grown in a test tube, under sterile conditions in special nutrient media. This capacity to generate a whole plant from any cell/explant is called {{c1::totipotency}}.The nutrient medium must provide a {{c1::carbon}} source such as sucrose and also inorganic salts, vitamins, amino acids and growth regulators like auxins, cytokinins etc.By application of these methods it is possible to achieve propagation of a large number of plants in very short durations. This method of producing thousands of plants through tissue culture is called {{c1::micro-propagation}}. Each of these plants will be genetically identical to the original plant from which they were grown, i.e., they are {{c1::somaclones}}. Tomato, banana, apple, etc., have been produced on commercial scale using this method.Another important application of the method is the recovery of healthy plants from diseased plants. Even if the plant is infected with a virus, the {{c1::meristem (apical and axillary)}} is free of virus. Hence, one can remove the meristem and grow it in vitro to obtain virus-free plants. Scientists have succeeded in culturing meristems of banana, sugarcane, potato, etc.Isolated protoplasts from two different varieties of plants – each having a desirable character – can be fused to get hybrid protoplasts, which can be further grown to form a new plant. These hybrids are called {{c1::somatic hybrids}} while the process called {{c1::somatic hybridisation.}}protoplast of tomato is fused with that of potato - {{c1::pomato}} |
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| Text | The Green Revolution succeeded in {{c1::tripling}} the food supply. Increased yields have partly been due to the use of improved crop varieties, but mainly due to the use of better management practices and use of agrochemicals (fertilisers and pesticides).However, for farmers agrochemicals are often too expensive, and further increases in yield with existing varieties are not possible using conventional breeding.Genetically modified crops is a possible alternative path to obtain maximum yield from farmer's fields and to minimise the use of fertilisers and chemicals.Plants, bacteria, fungi and animals whose genes have been altered by manipulation are called Genetically Modified Organisms (GMO). GM plants have been useful in many ways.Genetic modification has: (i) made crops more tolerant to abiotic stresses (cold, drought, salt, heat). (ii) reduced reliance on chemical pesticides (pest-resistant crops). (iii) helped to reduce post harvest losses. (iv) increased efficiency of mineral usage by plants (this prevents early exhaustion of fertility of soil). (v) enhanced nutritional value of food, e.g., {{c1::golden rice}}, i.e., Vitamin ‘{{c1::A}}’ enriched rice.GM has been used to create tailor-made plants to supply alternative resources to industries, in the form of starches, fuels and pharmaceuticals.Another application is production of pest resistant plants, which could decrease the amount of pesticide used. Bt toxin is produced by a bacterium called {{c1::Bacillus thuringiensis}}. Bt toxin gene has been cloned from the bacteria and been expressed in plants to provide resistance to insects without the need for insecticides; in effect created a bio-pesticide. Examples are Bt cotton, Bt corn, rice, tomato, potato and soyabean etc. |
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