BIOTECHNOLOGY AND ITS APPLICATIONS · Comparison Tables

1. Tissue culture vs somatic hybridisation

In-vitro plant biotechnology
Feature	Tissue culture	Somatic hybridisation
Basis	Whole plant regenerated from an explant in sterile nutrient medium.	Fusion of protoplasts from two different varieties/species.
Key property	Totipotency - each plant cell/explant can generate a whole plant.	Combines somatic cells after cell walls are removed.
Product	Micropropagation gives genetically identical somaclones.	Somatic hybrid, e.g. pomato from tomato and potato protoplasts.
NCERT use	Meristem culture produces virus-free plants.	Creates novel hybrid combinations, though not all are commercially useful.

2. Conventional breeding vs genetically modified crops

Routes to crop improvement
Feature	Conventional breeding	GM crop approach
Gene transfer	Transfers many genes together through crossing.	Introduces selected gene(s) through genetic manipulation.
Limitations / benefits	Slower and may bring undesirable genes.	Can create pest resistance, stress tolerance and enhanced nutrient value.
Examples	Improved varieties alongside agrochemical management.	Golden rice, Bt cotton and tailor-made plants for starches, fuels or pharmaceuticals.
Environmental aim	Often relies on fertilisers and pesticides.	Can reduce pesticide reliance and improve mineral-use efficiency.

3. Bt protoxin vs activated Bt toxin

How Bt crops kill susceptible insects
Feature	Bt protoxin in bacterium	Activated toxin in insect gut
State	Inactive crystalline protein; does not harm the bacterium.	Active form after alkaline pH solubilises and activates it.
Target	Produced by Bacillus thuringiensis.	Binds midgut epithelial cells of susceptible larvae, creates pores and causes cell lysis.
Use	cry genes are cloned into crop plants.	Gives crop resistance to specific insect groups.

4. Important cry genes and target pests

NCERT Bt crop examples
Gene / protein	Target	Key point
cryIAc and cryIIAb	Cotton bollworms	Genes selected according to crop and target pest.
cryIAb	Corn borer	Bt toxins are insect-group specific.
Bt crops	Cotton, corn, rice, tomato, potato and soybean	Express toxin gene and reduce insecticide requirement.
Other susceptible groups	Lepidopterans, coleopterans and dipterans	Different Bt strains produce proteins for different insects.

5. Sense RNA vs antisense RNA in RNA interference

RNAi-based nematode resistance
Feature	Sense RNA	Antisense RNA
Relationship	Has sequence corresponding to target mRNA.	Complementary to sense RNA / target mRNA.
When both are produced	They form double-stranded RNA (dsRNA), which initiates RNA interference.
Outcome	Specific mRNA is silenced, so translation does not occur. A tobacco plant expressing nematode-specific dsRNA resists Meloidogyne incognita.

6. Animal insulin vs recombinant human insulin

Insulin production for diabetes management
Feature	Animal-source insulin	Recombinant human insulin
Source	Pancreas of slaughtered cattle or pigs.	Human insulin DNA sequences expressed in E. coli.
Concern	Can cause allergy or immune reaction to foreign protein.	Matches human insulin and avoids this non-human-source issue.
Production	Extracted and purified from animals.	Eli Lilly (1983) produced A and B chains separately, then joined them by disulphide bonds.
C-peptide	Human proinsulin contains it; mature insulin does not.	Bacterial production bypassed the need to process a C-peptide by assembling separate chains.

7. Gene therapy vs enzyme replacement for ADA deficiency

Approaches to a hereditary immune disorder
Feature	Gene therapy	Enzyme replacement therapy
Principle	Introduces normal functional ADA gene to compensate for deleted/non-functional gene.	Provides functional ADA enzyme by injection.
Procedure in NCERT example	Patient lymphocytes are cultured, given ADA cDNA with retroviral vector and returned.	Repeated administration of enzyme.
Limitation / potential	Lymphocytes are not immortal, so periodic infusion is needed; early embryonic delivery may be permanent.	Not completely curative and requires repeated treatment.

8. PCR vs ELISA vs DNA/RNA probe

Early molecular diagnosis
Technique	What it detects	Principle / example
PCR	Very low amount of pathogen DNA/RNA or mutation.	Amplifies nucleic acid; used for HIV detection and suspected cancer mutations.
ELISA	Pathogen antigen or antibodies made against pathogen.	Based on antigen-antibody interaction.
Probe hybridisation	Specific normal or mutated DNA sequence.	Radioactively labelled single-stranded DNA/RNA hybridises with complementary sequence; detected by autoradiography.

9. Uses of transgenic animals

Why animals carrying foreign genes are made
Use	Purpose / example
Normal physiology and development	Studies gene regulation and roles in normal growth and development.
Disease models	Models of cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer's disease test treatments.
Biological products	Human alpha-1-antitrypsin for emphysema; transgenic cow Rosie produced human alpha-lactalbumin-enriched milk.
Vaccine and chemical safety	Transgenic mice test polio-vaccine safety; sensitive animals speed toxicity testing.

10. Biosafety regulation vs biopiracy

Ethical issues in biotechnology
Feature	Biosafety regulation	Biopiracy
Concern	Unpredictable ecosystem effects and safety of GM research/organisms.	Unauthorised use of bio-resources or traditional knowledge without compensation.
Indian example	GEAC evaluates validity of GM research and safety for public use.	Patent claims relating to Basmati, turmeric and neem raise benefit-sharing concerns.
Purpose	Responsible, regulated use of genetic modification.	Protects biodiversity-rich communities and countries from unfair commercial exploitation.