Mnemonics: Biotechnology & its Applications | Biology Class 12 - NEET PDF Download

1. Bt Cotton and Cry Genes

Concepts: Bacillus thuringiensis (Bt) produces Cry proteins (toxins) that kill insects (lepidopterans, coleopterans, dipterans); Cry genes (cryIAc, cryIIAb, cryIAb) cloned into crops like cotton; inactive protoxin activates in insect gut (alkaline pH), forming pores, causing cell lysis; Bt cotton resists pests, reducing insecticide use.
Mnemonic: "Bt’s Cry Toxin Rips Bollworms’ Guts, Cotton Booms"
Breakdown:

• Bt’s → Bacillus thuringiensis, the bacterium producing Cry proteins.

• Cry Toxin → Cry genes (cryIAc, cryIIAb for cotton bollworms; cryIAb for corn borer) encode toxic proteins, inactive as protoxins in Bt.

• Rips → Protoxin activates in insect gut (alkaline pH), forming pores in midgut epithelial cells, causing swelling, lysis, and death.

• Bollworms’ Guts → Specifically targets lepidopterans (e.g., tobacco budworm, armyworm), also coleopterans (beetles), dipterans (flies).

• Cotton → Bt cotton, genetically modified with Cry genes, resists pests without chemical insecticides.

• Booms → Bt cotton boosts yields by preventing pest damage, supporting the Green Revolution.

2. RNA Interference (RNAi)

Concepts: RNAi silences mRNA using double-stranded RNA (dsRNA); used in transgenic tobacco to resist nematodes (Meloidogyne incognita); Agrobacterium vectors introduce nematode-specific genes, producing sense/anti-sense RNA to form dsRNA, blocking nematode mRNA translation.
Mnemonic: "RNAi Mutes Nema, Tobacco Grows"
Breakdown:

• RNAi → RNA interference, a eukaryotic defense mechanism.

• Mutes → dsRNA binds and silences specific mRNA, preventing translation.

• Nema → Meloidogyne incognita, a nematode reducing tobacco yield.

• Tobacco → Transgenic tobacco uses Agrobacterium to express dsRNA.

• Grows → dsRNA kills nematodes, protecting tobacco roots.

3. Genetically Engineered Insulin

Concepts: Recombinant DNA produces human insulin in E. coli; insulin has A and B chains linked by disulfide bonds; pro-insulin with C peptide is matured by removing C peptide; Eli Lilly (1983) used plasmids to produce A and B chains separately, then combined them.
Mnemonic: "E. coli Builds Insulin, Chains Bond"
Breakdown:

• E. coli → Bacterium engineered for human insulin production.

• Builds → Eli Lilly (1983) used plasmids to produce A and B chains in E. coli.

• Insulin → Mature insulin lacks C peptide, unlike pro-insulin.

• Chains → A and B chains are produced separately.

• Bond → Chains combine via disulfide bonds, forming functional insulin.

4. Patents and Biopiracy

Concepts: Patents on biotech products (e.g., Basmati rice, turmeric, neem) raise ethical issues; biopiracy is unauthorized use of bio-resources/traditional knowledge without compensation; Basmati rice patent (1997) by a US company claimed Indian varieties; Indian Patents Bill and GEAC prevent biopiracy.
Mnemonic: "Basmati, Neem, Turmeric Nabbed, Patents Snatch, Laws Defend"
Breakdown:

• Basmati → 27 Indian Basmati varieties patented by a US company (1997).

• Neem → Indian neem, targeted for patenting traditional uses.

• Turmeric → Indian turmeric, subject to biopiracy for medicinal applications.

• Nabbed → Biopiracy steals bio-resources and traditional knowledge without authorization.

• Patents → Unfair patents claim Indian resources as “novelties,” restricting farmers.

• Snatch → Patents aggressively take control of traditional bio-resources.

• Laws → Indian Patents Bill and GEAC defend against exploitation.

• Defend → Legal measures protect India’s biodiversity and knowledge.

5. Tissue Culture and Micropropagation

Concepts: Tissue culture regenerates plants from explants via totipotency; micropropagation produces identical somaclones; uses nutrient media with sucrose, salts, vitamins, auxins, cytokinins; meristem culture yields virus-free plants (e.g., banana, sugarcane).
Mnemonic: "Explant Grows, Clones Bloom, Meristem Cleans"
Breakdown:

• Explant → Any plant part (e.g., cell, tissue) used in tissue culture.

• Grows → Totipotency allows explants to regenerate whole plants in nutrient media (sucrose, auxins, cytokinins).

• Clones → Micropropagation produces identical somaclones (e.g., tomato, banana).

• Bloom → Thousands of plants grow rapidly for commercial use.

• Meristem → Apical/axillary meristems, virus-free, cultured to produce healthy plants (e.g., sugarcane).

• Cleans → Meristem culture removes viruses, yielding disease-free plants.

6. Gene Therapy

Concepts: Gene therapy corrects genetic defects by inserting normal genes; first used in 1990 for adenosine deaminase (ADA) deficiency; functional ADA cDNA introduced into lymphocytes via retroviral vectors; embryonic gene insertion could be permanent.
Mnemonic: "ADA Gene Fixes Immune, Lymphocytes Heal"
Breakdown:

• ADA → Adenosine deaminase deficiency, a hereditary immune disorder.

• Gene → Functional ADA cDNA corrects the defective gene.

• Fixes → Gene therapy inserts normal genes to restore function.

• Immune → ADA is crucial for immune system function.

• Lymphocytes → Engineered lymphocytes receive ADA cDNA via retroviral vectors.

• Heal → Periodic infusions treat patients; embryonic therapy could be permanent.

7. Transgenic Animals

Concepts: Transgenic animals (e.g., mice) have foreign genes; used to study physiology, diseases (cancer, Alzheimer’s), biological products (α-1-antitrypsin), vaccine safety (polio), and toxicity testing; Rosie (transgenic cow) produced human alpha-lactalbumin milk.
Mnemonic: "Mice Genes Probe Disease, Rosie Milks Proteins"
Breakdown:

• Mice → Over 95% of transgenic animals are mice.

• Genes → Foreign genes inserted to study physiology (e.g., insulin-like growth factor).

• Probe → Transgenic animals model diseases (cancer, cystic fibrosis).

• Disease → Study gene roles in disease development.

• Rosie → Transgenic cow producing human alpha-lactalbumin milk (2.4 g/L).

• Milks → Biological products (e.g., α-1-antitrypsin for emphysema) and vaccine/toxicity testing.

• Proteins → Human proteins from transgenic animals aid medical treatments.