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Biology · AFCAT

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.

Part 1 — Recombinant DNA Technology

1. Tools of Recombinant DNA Technology

Restriction Enzymes

Function

Cut DNA at specific palindromic sequences; create sticky ends

AFCAT Analogy

Molecular scissors — precise cutters

DNA Ligase

Function

Joins (seals) cut DNA fragments; creates recombinant DNA

AFCAT Analogy

Molecular glue / stapler

Plasmids (Vectors)

Function

Small circular bacterial DNA; carries foreign gene into host cell

AFCAT Analogy

Molecular trucks — transport the gene

PCR

Function

Amplifies small DNA segment millions of times (thermal cycling)

AFCAT Analogy

Molecular photocopier

Gel Electrophoresis

Function

Separates DNA by size using electric current; small = farther

AFCAT Analogy

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.

Part 2 — Nutrition & Vitamins

3. Nutrition — Balanced Diet

Carbohydrates

Energy / Role

4 kcal/g — main energy source

Key Sources

Rice, wheat, potato, sugar, fruits

Deficiency

Fatigue, weight loss

Proteins

Energy / Role

4 kcal/g — growth, repair, enzymes

Key Sources

Legumes, eggs, milk, meat, fish

Deficiency

Kwashiorkor (protein), Marasmus (calorie+protein)

Fats

Energy / Role

9 kcal/g — energy store; fat-soluble vitamins; cell membranes

Key Sources

Oils, nuts, butter, meat

Deficiency

Fat-soluble vitamin deficiencies

Vitamin A

Energy / Role

Vision; immunity; skin health

Key Sources

Carrot, mango, liver, milk

Deficiency

Night blindness / Xerophthalmia

Vitamin C

Energy / Role

Collagen synthesis; immunity

Key Sources

Citrus, amla, guava, capsicum

Deficiency

Scurvy

Vitamin D

Energy / Role

Calcium absorption; bones and teeth

Key Sources

Sunlight (skin synthesis), fish oil, milk

Deficiency

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

(d) Agrobacterium

✓ Answer: (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

(d) Vitamin D

✓ Answer: (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

📝 Mocks 🎯 Quizzes