BIOTECHNOLOGY AND ITS APPLICATIONS

Totipotency = capacity to generate whole plant from any cell/explant.

Micropropagation → thousands of plants via tissue culture; genetically identical = somaclones.

Meristem (apical & axillary) = free of virus; in vitro culture → virus-free plants.

Somatic hybridisation = fusing protoplasts of two different plant varieties (after digesting cell walls); somatic hybrids.

Correct sequence of somatic hybridisation — Isolation of single cells from two different varieties of plants → Digestion of cell walls → Isolation of naked protoplasts → Fusion of protoplasts to get hybrid protoplast → Growing of hybrid protoplast to form a new plant.

GM plants — tolerant to abiotic stresses; pest-resistant; reduce post-harvest losses; increased mineral usage; enhanced nutrition (Golden Rice = Vitamin A).

Golden Rice = Vitamin A enriched rice (gene from Daffodil).

Bt toxin produced by Bacillus thuringiensis.

Bt toxin = inactive protoxin → activated by alkaline pH of insect gut → binds to midgut epithelial cells → creates pores → cell swelling & lysis → death.

The inactive form of Bt toxin is converted to the active form in the insect gut due to ALKALINE pH — not acidic pH, not by proteases, not by nucleases.

Crystals of Bt toxin do NOT kill the bacteria because toxin is inactive (not because bacteria are resistant, or toxin is in a special sac).

cry genes — cryIAc & cryIIAb = cotton bollworms; cryIAb = corn borer; toxin coded by gene cry; insect-group specific.

cryIAc & cryIIAb = cotton bollworms; cryIAb = corn borer — do not confuse!

cryIAc controls cotton bollworms and cryIAb controls corn borer, respectively. When the stem pairs cotton bollworms AND corn borer, respectively, the answer is cryIAc and cryIAb — cryIIAb is the second cotton bollworm gene and is the standing distractor.

Meloidogyne incognitia infects roots of tobacco plants → reduces yield.

RNAi takes place in all eukaryotic organisms as method of cellular defence.

Silencing of specific mRNA due to complementary dsRNA → prevents translation.

RNAi involves dsRNA (double-stranded RNA), NOT single-stranded RNA.

Silencing of a specific mRNA via RNAi is possible because of complementary dsRNA — not complementary tRNA, non-complementary ssRNA or inhibitory ssRNA.

Nematode-specific gene → produces both sense & anti-sense RNA → dsRNA → RNAi → mRNA silencing → parasite cannot survive.

Insulin earlier from pancreas of slaughtered cattle & pigs → allergy/reactions to foreign protein.

Insulin = two short polypeptide chains (A & B) linked by disulphide bridges.

Pro-hormone contains A, B & C peptide; C peptide removed during maturation; absent in mature insulin.

Eli Lilly (1983) → A & B chains produced separately in E. coli → combined by disulphide bonds → human insulin.

The genetically engineered organism used by Eli Lilly to prepare human insulin was a BACTERIUM (Escherichia coli) — not a virus, phage or yeast.

Gene therapy = correction of gene defect; delivery of normal gene to compensate for non-functional gene.

First gene therapy = 1990; 4-year-old girl; ADA deficiency.

ADA gene therapy — lymphocytes cultured outside body → functional ADA cDNA introduced (retroviral vector) → returned to patient; cells NOT immortal → periodic infusion needed.

Permanent cure = introduce ADA gene into cells at early embryonic stages.

Retroviral vector used to introduce DNA into human lymphocytes.

Conventional methods (serum & urine analysis) do NOT serve purpose of early diagnosis.

rDNA technology, PCR, ELISA — techniques for early diagnosis.

PCR used for HIV detection in AIDS patients; detecting gene mutations in cancer patients.

PCR is used for amplification of nucleic acids, NOT for purification of isolated proteins.

Probe = single-stranded DNA/RNA tagged with radioactive molecule; hybridises to complementary DNA; autoradiography.

Mutated gene → no complementarity with probe → does NOT appear on film.

ELISA based on antigen-antibody interaction.

95% of transgenic animals are mice.

α-1-antitrypsin = human protein used to treat emphysema.

The human protein α-1-antitrypsin obtained from transgenic animals is used for the treatment of emphysema — not Alzheimer disease, rheumatoid arthritis or cystic fibrosis.

Rosie (1997) = first transgenic cow; produced human protein-enriched milk (2.4 g/L); contained human alpha-lactalbumin.

GEAC = Genetic Engineering Approval Committee; set up by Indian Government; decisions on GM research validity & safety.

Biopiracy = use of bio-resources by MNCs without proper authorisation and without compensatory payment.

Biopiracy is by multinational companies/organisations, NOT by native people.

27 documented varieties of Basmati grown in India; American company patented Basmati (1997).