CBSE Class 12 Biology Revision Notes Chapter 12 - Biotechnology And Its Application
REVISION NOTES FOR CBSE CLASS 12 BIOLOGY CHAPTER 12
CHAPTER 12: BIOTECHNOLOGY AND ITS APPLICATION
Application of biotechnology in health and agriculture: Human insulin and vaccine production, stem cell technology, gene therapy; genetically modified organisms Bt crops; transgenic animals; biosafety issues, bio piracy and patents.
Biopesticides: Biological agents that are used to control weeds, insects and other pests.
cry Gene: The Bt toxins are coded by a gene named cry. cry Protein: The insecticidal protein which is produced by Bacillus thuringiensis.
Green Revolution : Substantial increase in crop yields due to use of high yielding varieties, use of fertilisers and pesticides, improved agricultural practices etc.
Genetically Modified Organisms (GMO): The organisms which have altered genes in them. These are also known as transgenic organisms.
e.g. Bt Cotton, Bt Corn, Transgenic rat, Transgenic cow-Rosie.
Molecular Diagnosis: Refers to early detection of diseases using recombinant DNA molecules and techniques like PCR and autoradiography.
RNA Interference (RNAI): Process used to develop pest resistant plants. It involves silencing of a specific mRNA due to complementary double stranded RNA.
Sustainable Agriculture: It involves organic farming and other integrated management practices which maintain soil fertility while increasing crop productivity.
Use of GM Plants: Tolerant to abiotic stress, Reduced dependence on chemical pesticides, less post harvest-loss, Efficient use of minerals, enhanced nutritional value.
¶ Bt, toxin protein exists as inactive pro-toxins, but once an insect ingest this inactive toxin, it is converted into active form of toxin due to the alkaline pH of the gut which solubilize the crystal. This causes swelling and lysis of epithelial cells of midgut leading to death of insect larvae.
¶ Bt toxin genes were isolated form Bacillus thuringiensis and incorporated into the several crop plants such as cotton.
¶ The proteins encoded by the genes: crylAc and cryllAb control cotton bollworms and crylAb controls corn borer.
Pest Resistant Plants: A nematode Meloidegyne incognitia infects tobacco plants and reduces their yield.
¶ Nematode specific genes were introduced into the host plant using Agrobacterium as a vector.
¶ The introduction of DNA was such that it produced both sense and antisense RNA in the host cells.
¶ These two RNAs being complementary to each other formed a double stranded RNA (dsRNA) making it inactive.
¶ The nucleotide formed by the process called RNA interference (RNA i).
¶ The result was that the parasite could not survive in the transgenic host and the transgenic plant got protected for the parasite.
GENETICALLY ENGINEERED INSULIN :
¶ The first clinical gene therapy was given in 1990 to a four year old girl with adenosine deaminase (ADA) deficiency. ADA enzyme is required for proper functioning of immune system.
¶ This disorder is caused due to the deletion of the gene for adenosine deaminase enzyme. In some children ADA deficiency can be cured by bone marrow transplantation. Lymphocytes from the blood of patient are grown in a culture. A functional ADA cDNA is then introduced into these lymphocytes using retroviral vector. The lymphocytes are transferred into the body of patients.
¶ As these cells are not immortal, the patient required periodic infusion of such genetically engineered lymphocytes.
¶ If a functional gene is Introduced into a bone marrow cells at early. embryonic stage. It could be a permanent cure of ADA deficiency,
VACCINE PRODUCTION
Vaccine are used to protect many infectious diseases such as small pox, cholera, Hepatitis B. These are made up of killed or weakened pathogens like viruses and bacteria..
Vaccines are commonly produced through cell cultures or animals or recombinant DNA technology.
Vaccine production involves the following steps.
(i) Generating the antigens: The antigens are generated from the microbes. Virus are grown in primary cells i.e., chicken egg (influenza vaccine) or on continuous cell lines i.e.. Human Cultured cells (Hepatitis B). Bacteria against which the vaccines are developed may be grown in bioreactors (Hib Vaccine)
(ii) Isolation of antigens: Antigen are isolated from the cells used to generate it.
(iii) Vaccine is made by adding adjuvant (to increase immune response of antigen), Stabilizers (to increase storage life) and preservatives to allow for the use of multi-dose vials).
PRODUCTION OF VACCINES THROUGH RECOMBINANT DNA TECHNOLOGY: Injectable and edible vaccines may be produced through recombinant DNA technology.
¶ Gene for antigen is isolated from pathogen like Virus.
¶ This desired gene is introduced in the host cells (yeast).
¶ Antigen gene is incorporated with genetic material of host.
¶ The host cell is allowed to grow in the culture.
Agrobacterium tumefaciens is commonly used to deliver the antigen genes into plant cells. Antigens are produced in the plant cells. The edible part of the plants can be consumed to get vaccinated. The transgenic crop plants have the capability to produce vaccine at larger scale and cheaper price.
STEM CELLS TECHNOLOGY
Stem Cells are undifferentiated cells which are able to grow into any type of tissue with specialized function. Stem cells are involved in development, growth and repair in multicellular organisms. Stem cells are used to treat many diseases such as type-I diabetes, heart diseases, cancer, Spinal injuries, arthritis, muscular dystrophy, Alzheimer. It can also be used to make new organs like heart, liver, kidneys, skin, even to produce transgenic animals.
Sources of Stem Cells: Stem cells can be obtained from inner cell mass of embryos, from bone marrow, umbilical cord and amniotic fluid.
THERE ARE THREE CATEGORIES OF STEM CELLS:
1. Embryonic stem cells: The embryo cells are removed easily and cultured in laboratory.
2. Tissue stem cells: Bone marrow stem cells can be used to produce bone or cardiac muscle cells.
3. Reprogrammed stem cells: Adult special cells are reprogrammed to act as embryonic cells with the help of genetic engineering. Organs for transplantation are developed by this technique.
¶ Embryonic stem cells have the ability to differentiate into any at the three germ layers-ectoderm, mesoderm or endoderm.
¶ These cells are isolated from inner cells mass of the blastocyst, 4 to 5 days after in vitro fertilisation of an egg.
¶ The cells are cultured and allowed to grow into cell lines.
Transgenic animals: The animals which carry foreign genes are called transgenic animals.
STEPS TO PRODUCE TRANSGENIC ANIMALS:
1. Identification and isolation of desired gene.
2. Selection of proper vector or direct transmission of desired gene.
3. Combining of desired gene with the vector using ligase enzyme.
4. Introduction of vector in cells/tissue/embryo/mature individual.
5. Expression of foreign gene in transgenic animal.
ADVANTAGES OF TRANSGENIC ANIMALS :
1. Transgenic animals are used to produce the biological products. For example, Rosie (First transgenic cow) produced human alpha-lactalbumin protein enriched milk which was more balanced product for human babies than natural cow-milk.
2. Transgenic mice are used in testing of the vaccine safety before these vaccines are used on humans e.g. Polio Vaccine.
3. Transgenic animal are used to test the toxicity of substances.
4. These animals are used to study how genes contribute to the development of disease and also treatment. Example: cancer, Alzheimer's etc.
5. These animals are used to study the regulation of genes and their affect for normal functioning of the body and its development.
Patent: Patent is a set of exclusive right granted by a state (National Government) to an inventor or their assignee for a limited period of time to prevent others from commercial use of his invention. Biopatents are granted for biological entities and for products derived from them.
CRITERIA FOR GRANT OF PATENTS:
1. Novelty: It implies that the innovation must be new.
2. Non-obviousness: It implies that it may not be documented but is otherwise well-known.
3. Utility: The discovered fact or product should be of a particular use for humans.
CONTROVERSIES IN INDIA REGARDING PATENT AND BIOPIRACY:
Turmeric : In 1995, the US pantent office granted a patent to the University of mississippi medical centre for "Use of Turmeric in wound healing". Dr. R.A. Mashelkar, an Indian scientist challenged the patent. It was established that the use of turmeric as healing agent was well-known in India for centuries and the patent was revoked.
Neem: The European Patent office, Munich granted a patent to the firm of W.R. grace & Co. for 'Fungicidal uses of neem oil'. The patent had been granted on an extraction of oil technique but not on the neem tree itself. In 1996. Vandana Shiva and Ajay Phadke who had rereared neem in India, challenged the patent. Legal action was followed by India Government. Finally, the patent was revoked in 2005.
Basmati Rice: Basmati Rice is a variety of rice which is distinct for its unique aroma and flavour. In India, 27 varieties of basmati are grown. In September 1997, a Texas company patented Basmati rice lines and grains through the US patent and trademark office. This act caused diplomatic crisis between India and US. Later due to revised decision by the United State patent office, the Texas company lost most of the claims of the patent. This was a case of biopiracy.
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