Quick Revision Notes: Class 12 Biology

Chapter: Biotechnology and its Applications (जैव प्रौद्योगिकी एवं उसके उपयोग)

### Concept 1: Biotechnological Applications in Agriculture (कृषि में जैव प्रौद्योगिकी के उपयोग)

To enhance food production, biotechnology has been used to create genetically modified crops (GMOs).

• Genetically Modified Organisms (GMOs): Plants, bacteria, fungi, and animals whose genes have been altered by manipulation are called GMOs.
• Bt Cotton (बी.टी. कपास):
  • Produced by introducing a cry gene cloned from the bacterium Bacillus thuringiensis.
  • The protein encoded by the cry gene forms crystal proteins containing toxic insecticidal proteins.
  • When ingested by insect pests (like bollworms), the alkaline gut of the insect solubilizes the crystals, converting the protoxin into an active toxin that creates pores, leading to cell lysis and death.
  • Specific Genes:
    • cryIAb controls Corn borer.
    • cryIAc and cryIIAb control cotton bollworms.
• Pest Resistant Plants (RNA Interference / RNAi):
  • A method used to silence specific mRNA due to a complementary dsRNA molecule.
  • Example: Nematode Meloidegyne incognita infects tobacco roots. RNAi silences the essential genes of the nematode, preventing its infection in transgenic tobacco plants.

### Concept 2: Biotechnological Applications in Medicine (चिकित्सा में जैव प्रौद्योगिकी के उपयोग)

Recombinant DNA technology has revolutionized human healthcare by enabling mass production of safe and effective therapeutic drugs.

• Genetically Engineered Insulin (ह्यूमुलिन / Humulin):
  • Insulin consists of two short polypeptide chains: Chain A and Chain B, linked by disulfide bridges.
  • In mammals, insulin is synthesized as a pro-hormone containing an extra stretch called the C-peptide (which is removed during maturation).
  • Eli Lilly (an American company) in 1983 prepared two DNA sequences corresponding to A and B chains of human insulin and introduced them in E. coli plasmids to produce insulin chains separately, which were later extracted and combined by creating disulfide bonds.
• Gene Therapy (जीन चिकित्सा):
  • A method that allows correction of a gene defect diagnosed in a child/embryo.
  • First Clinical Gene Therapy (1990): Given to a 4-year-old girl with Adenosine Deaminase (ADA) deficiency (caused by deletion of the gene for ADA, crucial for immune system functioning).
  • Treatment: Lymphocytes from the patient's blood are grown in culture, a functional ADA cDNA is introduced using a retroviral vector, and these cells are infused back into the patient. (Permanent cure if gene isolate from bone marrow cells is introduced at early embryonic stages).
• Molecular Diagnostics (आणविक निदान):
  • PCR (Polymerase Chain Reaction): Detects very low concentration of bacteria or viruses even before symptoms appear by amplifying their nucleic acid.
  • ELISA (Enzyme-Linked Immunosorbent Assay): Based on antigen-antibody interactions. Used for the early detection of HIV.
  • Autoradiography: A single-stranded DNA or RNA tagged with a radioactive molecule (probe) is allowed to hybridize to its complementary DNA in a clone of cells, detected by autoradiography to identify mutated genes.

### Concept 3: Transgenic Animals (पारजीवी जंतु)

Animals that have had their DNA manipulated to possess and express an extra (foreign) gene are known as transgenic animals.

• Reasons/Uses of Transgenic Animals:
  1. Study of Normal Physiology and Development: To understand how genes are regulated and affect normal functions.
  2. Study of Diseases: Created as models for human diseases (cancer, cystic fibrosis, Alzheimer's) to investigate new treatments.
  3. Biological Products: Can produce useful biological products for human use. Example: Alpha-1-antitrypsin used to treat emphysema. The first transgenic cow, Rosie (1997), produced human protein-enriched milk (2.4 g/L), containing human alpha-lactalbumin.
  4. Vaccine Safety: Used to test the safety of vaccines (e.g., polio vaccine) before they are used on humans.
  5. Chemical Safety Testing: Known as toxicity/safety testing or safety evaluation to check toxicity of drugs.

### Concept 4: Ethical Issues and Biopiracy (नैतिक मुद्दे एवं बायोपाईरेसी)

The manipulation of organisms by biotechnology has raised public concerns regarding ethical, safety, and legal issues.

• GEAC (Genetic Engineering Appraisal Committee): An Indian government organization that makes decisions regarding the validity of GM research and the safety of introducing GM-organisms for public services.
• Biopiracy (बायोपाईरेसी): The use of bio-resources by multinational companies and other organizations without proper authorization from the countries and people concerned without compensatory payment.
  • Example: Patenting of Indian Basmati rice by an American company (RiceTec) through an American patent and trademark office, even though Basmati is indigenous to the Indian subcontinent.
• Biopatent: A patent granted by the government to an inventor for biological entities and products derived from them.
• Indian Patent Bill: The Indian Parliament has cleared recently the second amendment of the Indian Patents Bill, taking such issues into consideration, addressing patent terms, emergency provisions, and research initiative terms.