Transgenic Animals and Plants NEET Notes | EduRev

Biology Class 12

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NEET : Transgenic Animals and Plants NEET Notes | EduRev

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APPLICATIONS OF  TRANSGENIC PLANTS:

1. They have proved to be extremely valuable tools in studies on plant molecular biology, regulation of gene action, identification of regulatory promontory sequences etc.

2. Specific genes have been transferred into plants to improve their agronomic and other features.

3. Genes for resistance to various biotic stresses have been engineered to generate transgenic plants resistant to insects viruses etc. 

4. Several gene transfers have been aimed at improving the produce quality e.g., protein or lipid quality etc. of transgenic plants ;

5. Transgenic plants are aimed to produce novel biochemicals like interferon, insulin, immunoglobulins etc.,

6. Transgenic plants have been produced that express a gene encoding an antigenic protein from a pathogen.

7. Made crops more tolerant to  abiotic stresses (cold, drought, salt, heat).

8. Reduced reliance on chemical pesticides (pest-resistant crops).

9. Helped to reduce post harvest losses.

10. Increased efficiency of mineral usage by plants (this prevents early exhaustion of fertility of soil).

11. Enhanced nutritional value of food e.g., Vitamin 'A' enriched rice.

Genetic modified food– The food is prepared from genetically modified crop[transgenic] is called genetically modified food or G.M.Food.

GM food differs from the food prepared from the produce of conventionally developed varieties mainly in the following aspects.Firstly, it contains the protein produced by the trangene in question, e.g., Cry protein in the case of insect resistant varieties. Secondly,it contains the enzyme produced by the antibiotic resistance gene that was used during gene transfer by genetic engineering. Finally, it contains the antibiotic resistance gene itself.

GM foods could lead to the following problems when they are consumed. Firstly, the transgene product may toxicity and or produce allergies. Secondly, the enzyme produced by the antibiotic resistance gene could cause allergies, since it is a foreign protein.Finally, the bacteria present in the alimentary canal of the humans could take up the antibiotic resistance gene that is present in the GM food.

Biochemical Production Plants are the chief source carbohydrates, e.g., starch, sugar etc., lipids, proteins, and a variety of unique biochemicals. Transgenes have been shown to introduce novel branches in the biosynthetic pathways of plants and, thereby, to generate valuable products or to produce new, valuable proteins virtually all the cases are promising and in developmental stages, except for the thrombin inhibitor protein hirudin, which is the first commercial example - Hirudin.

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 percent 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 (a-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 that 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.

Sustainable Agriculture – Sustainable agriculture primarily use renewable resources, would cause minimum pollution and maintain the optimum yield level. Any development that reduce the use of non renewable resources and level of pollution, would enhance the sustainability of agriculture. Biotechnology play significant role in sustainable agriculture by the use of biofertilizer, biopesticides, disease and insect resistant varieties etc.  Biopatent – A patent is a right granted by a government to an inventor to prevent others from commercial use of his invention. A patent is granted for – (A) An invention [including product]

(B) An improvement in an earlier invention

(C) The process of generating products and

(D) A concept or design.

These products are called biopatents because they are granted for biological entities.

Biopatents are awarded for the following :

(i) strains of microorganisms,

(ii) cell lines,

(iii) genetically modified strains of plants and animals,

(iv) DNA sequences,

(v) the proteins encoded by DNA sequences,

(vi) various biotechnological procedures,

(vii) production processes,

(viii) products, and

(ix) product applications.

For example, one patent covers'all transgenic plants of Brassica family'. Such broad patents are considered morally unacceptable and fundamentally inequitable.

Biopiracy – Many organisations and multinational companies exploit or patent bilogical resources or bioresources of other nations without proper authorisation from the countries concerned is known as biopiracy.
The industrialised nations are rich in technology and financial resources but poor in biodiversity and traditional knowledge related to the utilisation of the bioresources. In contrast, developing nations are poor in technology and financial resources, but are rich in biodiversity and traditional knowledge related to bioresources.

Biological resources or bio-resources include all those organisms that can be used to derive commercial benefits. Traditional knowledge related to bio-resources is the knowledge developed by various communities over long periods of history, regarding the utilisation of the bio-resources, e.g., use of herbs, etc, as drugs.

Institutions and companies of industrialised nations are collecting and exploiting the bio-resources, as follows.

(i) The are collecting and patenting the genetic resources themselves. For example, a patent granted in U.S.A. covers the entire 'basmati' rice germplasm indigenous to our country.

(ii) The bio-resources are being analysed for identification of valuable biomolecules. A biomolecule is a compound produced by a living organism. The biomolecules are then patented and used for commercial activities.

(iii) Useful genes are isolated from the bio-resources and patented. These genes are then used to generate commercial products.
A west African plant Pentadiplandra brazzeana produces a protein called Brazzein which is approximately 2000 times more sweeter than sugar. It is proposed to transfer the Brazzein gene into maize and express it in maize Kernels.

But the protein Brazzein was patented in U.S.A. Subsequently, the gene encoding brazzein was isolated and patented in U.S.A.
Bio-war – Bio-war or biological war is the use of biological weapons against humans or their crops and animals.
Bio-weapons are a device that carries and delivers to the target organism in the form of pathological biological agents or toxins called "bio-weapon agent".

Bio-weapon agent is kept in a suitable container so that it remains active and virulent during delivery. This container could be delivered in various ways, including missiles and aircraft. The use of biological agents in war may date back to 5th century B.C.
Some of the potential pathogen for bio-weapons are those that causes Anthrax, Small pox and Botulinum toxin. These bio weapons sent either through letters (envelopes) as powder or in the form of spray.

The possible defence against bio-weapons include the use of respirator or gas mask, vaccination, administration of appropriate antibiotics, and decontamination. In addition, sensitive detection systems should be developed to control and minimise damage.

Transgenic Animals and Plants NEET Notes | EduRevTransgenic Animals and Plants NEET Notes | EduRevTransgenic Animals and Plants NEET Notes | EduRev

Benefits of Biological Weapons over Conventional Weapons -.

i) Biological weapons or agents for biological warfare are not costly and can be produced with ease. ii). Detection is almost impossible. iii). Use is likely to increase. iv). They are more dangerous than conventional weapons.

Potential Biological Weapon Agents -.

i Anthrax → Bacillus anthracis. ii. Botulinum toxin (Botulin) → Clostridium botulinum. iii. Plague → Yersinia pestis. iv. Viral Encephalitides → Alpha virus.

Ethics includes a set of standards by which a community regulates its behaviour and decides as to which activity is legitimate and which is not. Therefore bioethics may be viewed as a set of standards that may be issued to regulate our activities in relation to the biological world.
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 major bioethical concerns pertaining to biotechnology are summarised below.

(i) Use of animals in biotechnology causes great suffering to them.
(ii) When animals are used for production of pharmaceutical proteins, they are virtually reduced to the status of a 'factory'.
(iii) Introduction of a transgene from one species into another species violates the 'integrity of species'.
(iv) Transfer of human genes into animals (and vice-versa) dilutes the concept of 'humanness'.
(v) Biotechnology is disrespectful to living beings, and only exploits them for the benefit of human beings.
(vi) Biotechnology may pose unforeseen risks to the environment, including risk to biodiversity.

Bioethics in Plant Genetic Engineering The GM crops are fast becoming a part of agriculture throughout the world because of their contribution to the increased crop productivity and to global food, feed and fiber security, besides their use in health-care and industry. However, the constraints associated with public acceptance of transgenic crops continue to be important challenges facing the global community. The following are the major concerns about GM crops and GM food :

  • The safety of GM food for human and animal consumption (e.g. GM food may cause allergenicity).

  • The effect of GM crops on biodiversity and environment.

  • The effect of GM crops on non-target and beneficial insects/microbes.

  • Transgenes may escape through pollen to related plant species (gene pollution) and may lead to the development of supper weeds.

  • The GM crops may change the fundamental vegetable nature of plants as the genes from animals (e.g. fish or mouse) are being introduced into crop plants.

  • The antibiotic resistance marker genes used to produce transgenic crops may horizontally transfer into microbes and thus exacerbate problem of antibiotic resistance in human and animal pathogens (i.e. transgenes may move from plants to gut microflora of humans and animals).

  • The GM crops may lead to the change in the evolutionary pattern.

Bio-pesticides: Bio-pesticides are those biological agents that are used for control of weeds, insects and  pathogens. The micro-organisms used as bio-pesticides include viruses, bacteria, fungi, protozoa and mites.

One example is the soil bacterium, Bacillus thuringiensis. Spores of this bacterium produce the insecticidal Cry protein. Therefore, spores of this bacterium kill larvae of certain insects. The commercial preparations of B. thuringiensis contain a mixture of spores, Cry protein and an inert carrier. This bacterium was the first bio-pesticide to be used on a commercial scale in the world.

The very familiar beetle with red and black markings-the Ladybird, and Dragonflies are useful to get rid of aphids and mosquitoes, respectively. An example of microbial bio-control agents that can be introduced in order to control butterfly caterpillars is the bacteria Bacillus thuringiensis (often written as Bt). These are available in sachets as dried spores which are mixed with water and sprayed onto vulnerable plants such as brassicas and fruit trees, where these are eaten by the insect larvae. In the gut of the larvae, the toxin is released and the larvae get killed. The bacterial disease will kill the caterpillars, but leave other insects unharmed.

Fungal pathogens are attractive bio-control agents for weed control in view of their host specificity and ease in production and inoculation in the field where, A biological control being developed for use in the treatment of plant disease is the fungus Trichoderma.
Trichoderma species are free-living fungi that are very common in the root ecosystems. They are effective bio-control agents of several plant pathogens.

Baculoviruses are pathogens that attack insects and other arthropods. The majority of baculoviruses used as biological control agents are in the genus Nucleopolyhedrovirus. These viruses are excellent candidates for species-specific, narrow spectrum insecticidal application. They have been shown to have no negative impacts on plants, mammals, birds, fish or even on non-target insects. This is especially desirable when beneficial insects are being conserved to aid in an overall integrated pest management (IPM) programme, or when an ecologically sensitive area is being treated.  

Between bio-pesticides and chemical pesticides

 

Biopesticides

Chemical pesticides

1. 

These do not harm nontarget species.

Nontarget species are also harmed.

2. 

They do not pollute the environment.

Cause pollution by chemical farming; sometimes serious.

3. 

No harmful residues remain in food, fodder and fibers

Harmful residues may often remain in food,fodder and fibers.

4. 

Relatively Cheaper.

Relatively costlier

5. 

Insects are expected not to develop resistance to Bio-pesticides.

Insects may become resistant, e.g., Heliothis Has become resistant to most insecticides.

6. 

Since they are highly specific, correct identification of the pest is essential.

It is often not critical.

7.

High specificity may often make the use of two or more bio-pesticides necessary.

often not required.

8. 

Performance may be variable due to the influence of biotic and abiotic factors of the environment.

This is not often the case.

 

Biofertilisers: Bio-fertilisers are organisms that enrich the nutrient quality (N,P) of the soil. The main sources of bio-fertilisers are bacteria, fungi and cyanobacteria.

Bacteria Rhizobium (symbiotic bacteria) fix atmospheric nitrogen into organic forms, which is used by the plant as nutrient.
Other bacteria like Azospirillum and c Azotobacter can fix atmospheric nitrogen while free-living in the soil thus enriching the nitrogen content of the soil.

Fungi are also known to form symbiotic associations with plants (mycorrhiza). Many members of the genus Glomus form mycorrhiza.
Fungal symbiont in these associations absorbs phosphorus from soil and passes it to the plant. Also provide resistance to root-borne pathogens, tolerance to salinity and drought and cause an overall increase in plant growth and development.

Cyanobacteria are autotropic microbes widely distributed in aquatic and terrestrial environments many of which can fix atmospheric nitrogen. (e.g. Anabaena, Nostoc, Oscillatoria, etc.) In paddy fields, cyanobacteria serve as an important bio-fertiliser. Blue green algae also add organic matter to the soil and increase its fertility.

Bio-fertilisers are a low-cost input and they do not pollute the environment. They are use to replenish soil nutrients. They also reduce the dependence on chemical fertilisers and also help to use organic farming.

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