Biotechnology & Diseases — NEET Zoology Notes

1. Introduction & Objectives

Explore pathogen life cycles and human immune system structures. By the end of this module, you will understand:

• The diagnostic lifecycle of *Plasmodium* parasites.
• Humoral vs Cell-Mediated immunity and graft rejection.
• Clinical diagnostics of AIDS and Cancer pathways.

Estimated Reading Time: 25 minutes  |  Difficulty Level: Moderate  |  Prerequisites: Basic cell biology.

2. Why Should You Learn This?

Immunology is central to vaccine design, epidemiological surveillance, organ transplant grafting, and oncology treatments.

5. Detailed Explanation & 10. Scientific Terminology

• Plasmodium Life Cycle: Sporozoites (infective stage) enter blood from female *Anopheles* bite. Reproduce in liver, then attack RBCs. Rupture of RBCs releases toxic **Hemozoin**, causing malaria chills and fever.
• Immunity: Innate barriers vs acquired immunological memory. Humoral immunity relies on B-cell antibodies. Cell-Mediated Immunity (CMI) relies on T-cells and is responsible for graft rejection.

Common Human Diseases & Their Pathogens

Vaccination gives active immunity by exposing the body to a harmless antigen so memory cells form; AIDS (HIV, a retrovirus) destroys helper-T cells; cancer is uncontrolled cell division (proto-oncogenes → oncogenes).

Types of Immunity

An antibody is a Y-shaped protein of four chains (H₂L₂) — two heavy, two light. The secondary immune response (on re-exposure) is faster and stronger than the primary response, thanks to memory cells — the basis of vaccination.

Adolescence — Drug & Alcohol Abuse

Commonly abused drugs: opioids (heroin/smack — a depressant, from Papaver somniferum), cannabinoids (from Cannabis sativa), and coca alkaloids/cocaine (a stimulant). Tobacco contains nicotine, raising the risk of cancer and cardiovascular disease. Warning signs include falling performance, withdrawal and risk-taking; prevention needs education, counselling and support.

5. Detailed Explanation & 10. Terminology

• Restriction Enzymes: Cut double-stranded DNA at palindromic sequences. E.g., EcoRI cuts at GAATTC, leaving single-stranded overhanging sticky ends.
• Gel Electrophoresis: Separates DNA towards anode via agarose gel. Bands are stained with Ethidium Bromide, visible as bright orange under UV. Elution extracts bands.

Tools & Steps of Recombinant DNA Technology

• Tools: restriction enzymes ("molecular scissors"), DNA ligase ("molecular glue"), a vector (plasmid such as pBR322, or a phage) to carry the gene, and a competent host cell.
• Steps: (1) isolate the gene of interest, (2) cut gene and vector with the same restriction enzyme, (3) ligate to form recombinant DNA, (4) transfer into the host, (5) culture and select recombinants, (6) grow at scale in a bioreactor, (7) downstream processing (purification and formulation).

5. Detailed Explanation & 10. Terminology

• Bt Cotton: *Bacillus thuringiensis* crystal proteins exist as inactive protoxin, solubilized and activated by the **alkaline pH** of insect midgut, creating cell-lysing pores.
• Humulin: Eli Lilly (1983) synthesized DNA chains A and B separately, expressing them in *E. coli* plasmids. Combined chains in vitro with disulfide bonds to produce mature insulin.

Gene Therapy, Transgenics & Diagnostics

• Gene therapy: correcting a genetic defect by inserting a functional gene — the first clinical case treated ADA deficiency (severe combined immunodeficiency).
• Transgenic animals: carry a foreign gene — used for studying disease, producing useful proteins (e.g. human protein in milk) and testing vaccines/toxicity.
• Molecular diagnostics: PCR detects a pathogen's nucleic acid before symptoms appear; ELISA detects antigens or antibodies (used for HIV screening).
• Biosafety: concerns over biopiracy and patents are overseen in India by the GEAC (Genetic Engineering Appraisal Committee).