BA06 — Biotechnology & Everyday Biology

📖 BA06 · AFCAT General Awareness — Biology AFCAT Level — Low-Yield, Full-Marks Territory

Short, factual, and fully learnable. Questions are direct: what is Bt cotton, how is insulin made, what does a restriction enzyme do, which vitamin does sunlight synthesise? Five focused sessions cover this chapter completely.

✈ AFCAT Focus: Restriction enzyme = molecular scissors; plasmid = vector; Bt cotton = Bacillus thuringiensis gene → Cry protein kills bollworm (India 2002); Humulin = recombinant insulin from E. coli (1982); fat-soluble = A, D, E, K; Vitamin D made by sunlight in skin.

1. Tools of Recombinant DNA Technology

Tool	Function	AFCAT Analogy
Restriction Enzymes	Cut DNA at specific palindromic sequences; create sticky ends	Molecular scissors — precise cutters
DNA Ligase	Joins (seals) cut DNA fragments; creates recombinant DNA	Molecular glue / stapler
Plasmids (Vectors)	Small circular bacterial DNA; carries foreign gene into host cell	Molecular trucks — transport the gene
PCR	Amplifies small DNA segment millions of times (thermal cycling)	Molecular photocopier
Gel Electrophoresis	Separates DNA by size using electric current; small = farther	Molecular sieve

2. Applications — Medicine & Agriculture

💊 Medical Applications

Humulin (Recombinant Insulin): Human insulin gene into E. coli → bacteria produce human insulin. First recombinant drug (FDA, 1982). Treats Type 1 Diabetes.
Gene Therapy: Inserts functional gene to correct genetic defect. Used for SCID ("bubble boy" disease).
Recombinant Vaccines: Hepatitis B vaccine via recombinant yeast. No live pathogen needed.

🍁 Agricultural Biotechnology

Bt Cotton: Gene from Bacillus thuringiensis produces Cry protein. Toxic to cotton bollworm larvae (alkaline gut activates it). Harmless to mammals (acidic gut). Approved in India 2002 by GEAC.
Golden Rice: Beta-carotene gene inserted → produces Vitamin A precursor. Addresses Vit A deficiency in developing nations.

3. Nutrition — Balanced Diet

Nutrient	Energy / Role	Key Sources	Deficiency
Carbohydrates	4 kcal/g — main energy source	Rice, wheat, potato, sugar, fruits	Fatigue, weight loss
Proteins	4 kcal/g — growth, repair, enzymes	Legumes, eggs, milk, meat, fish	Kwashiorkor (protein), Marasmus (calorie+protein)
Fats	9 kcal/g — energy store; fat-soluble vitamins; cell membranes	Oils, nuts, butter, meat	Fat-soluble vitamin deficiencies
Vitamin A	Vision; immunity; skin health	Carrot, mango, liver, milk	Night blindness / Xerophthalmia
Vitamin C	Collagen synthesis; immunity	Citrus, amla, guava, capsicum	Scurvy
Vitamin D	Calcium absorption; bones and teeth	Sunlight (skin synthesis), fish oil, milk	Rickets (children) / Osteomalacia (adults)

💡 Fat-Soluble vs Water-Soluble Vitamins:
Fat-soluble: A, D, E, K — stored in fat tissue; can accumulate to toxic levels
Water-soluble: All B vitamins + Vitamin C — not stored; excess excreted in urine
Vitamin D only: synthesised in skin by UVB sunlight — the only vitamin that acts as a hormone

📝 AFCAT PYQs — Biotechnology & Nutrition

Q1. Bt cotton contains a gene from: AFCAT PYQ

(a) E. coli(b) Rhizobium(c) Bacillus thuringiensis(d) Agrobacterium

✔ (c) Bacillus thuringiensis

The Cry protein produced by the Bt gene is activated in the alkaline insect gut — kills bollworm larvae. Human and animal guts are acidic, so the protein is harmless to mammals. First approved GM crop in India (2002).

Q2. Which vitamin is synthesised when skin is exposed to sunlight? AFCAT PYQ

(a) Vitamin A(b) Vitamin B₁₂(c) Vitamin C(d) Vitamin D

✔ (d) Vitamin D

Vitamin D is synthesised in skin when 7-dehydrocholesterol absorbs UVB radiation. It regulates calcium absorption — deficiency causes rickets (children) or osteomalacia (adults). The only vitamin that functions as a hormone.

🧠 Quick Memory Chart — BA06

📈 Biotech Tools

Restriction enzyme: molecular scissors
DNA ligase: molecular glue
Plasmid (vector): molecular truck
PCR: copies DNA millions of times
Gel electrophoresis: separates by size

🍁 Applications

Bt cotton: B. thuringiensis gene (2002)
Cry protein: kills bollworm larvae
Humulin: insulin from E. coli (1982)
Golden Rice: beta-carotene (Vit A)
Gene therapy: corrects genetic defects

🍕 Vitamins

Fat-soluble: A, D, E, K
Water-soluble: B-complex + C
A: night blindness | C: scurvy
D: rickets | B₁: beriberi
Vit D: only vitamin made by sunlight

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