CSIR NET Life Sciences Applied Biology Flashcards

24 sample cards from the Applied Biology deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. What is Bt cotton and how does it confer insect resistance?

   Transgenic cotton expressing the cry (crystal protein) gene from Bacillus thuringiensis; the Cry endotoxin is activated in the insect gut and lyses gut epithelial cells, killing bollworm larvae.

2. What is Golden Rice engineered to produce and why?

   Transgenic rice engineered to synthesize beta-carotene (provitamin A) in the endosperm by inserting phytoene synthase (psy) and crtI genes, to combat vitamin A deficiency.

3. What is animal cell culture and its main applications?

   In-vitro maintenance and growth of animal cells in suitable media; used for producing vaccines, recombinant proteins and monoclonal antibodies, toxicity testing, virology, and as models for research.

4. What is the difference between transgenic and cloned animals?

   A transgenic animal has a foreign gene deliberately introduced into its genome (e.g., for producing pharmaceuticals). A cloned animal (e.g., Dolly) is a genetic copy produced by somatic cell nuclear transfer without adding foreign genes.

5. What is molecular pharming (gene farming) in animals?

   Use of transgenic animals to produce valuable recombinant proteins (e.g., human proteins, antibodies, clotting factors) in their milk, blood, or eggs—e.g., the drug ATryn (antithrombin) from transgenic goat milk.

6. What technique created Dolly the sheep and what does it demonstrate?

   Somatic Cell Nuclear Transfer (SCNT): nucleus from an adult somatic cell is transferred into an enucleated egg, which is implanted; it demonstrated that a differentiated adult nucleus can be reprogrammed to totipotency.

7. What is a molecular approach to disease diagnosis and one key advantage over conventional methods?

   Detecting disease at the level of nucleic acids or specific proteins (PCR, probes, sequencing, microarrays). Advantage: high sensitivity and specificity, enabling early detection before symptoms or culture results, and identification of non-culturable pathogens.

8. How does a nucleic acid probe work in diagnosis?

   A labelled single-stranded DNA/RNA complementary to a target sequence hybridizes specifically to the pathogen's/gene's nucleic acid; the label (radioactive, fluorescent, enzymatic) is then detected to confirm presence of the target.

9. What is a DNA microarray and its diagnostic use?

   A solid chip carrying thousands of immobilized DNA probes; labelled sample nucleic acids hybridize to complementary spots, allowing simultaneous detection of many genes/pathogens or genome-wide expression profiling for disease characterization.

10. What molecular markers/methods are used for microbial strain identification?

    16S rRNA gene sequencing (bacteria), ITS sequencing (fungi), RFLP, RAPD, AFLP, PFGE, ribotyping, MLST (multilocus sequence typing), and whole-genome sequencing.

11. Why is the 16S rRNA gene the standard for bacterial identification?

    It is universally present, contains both highly conserved regions (for primer binding) and variable regions (species-specific), and is not subject to horizontal transfer, allowing reliable comparison and phylogenetic placement of bacteria.

12. What is DNA fingerprinting and on what variation is it based?

    A technique to identify individuals based on differences in repetitive DNA sequences—originally VNTRs (minisatellites) and now STRs (microsatellites); each individual's pattern is unique (except identical twins). Used in forensics, paternity, and diversity studies.

13. Give two ways biotechnology is applied to human health.

    Production of therapeutics (recombinant insulin, vaccines, monoclonal antibodies, interferons) and diagnostics/gene therapy (molecular diagnosis of genetic and infectious diseases, gene therapy for disorders like SCID).

14. What is gene therapy and its two main types?

    Introduction/correction of genes to treat disease. Somatic gene therapy targets body cells (non-heritable); germline gene therapy targets gametes/embryos (heritable, ethically restricted). First successful trial: ADA-SCID.

15. List major applications of biotechnology in agriculture.

    Development of insect-, herbicide-, and virus-resistant crops; abiotic stress tolerance; improved nutrition (biofortification); biofertilizers and biopesticides; marker-assisted breeding; and micropropagation of elite/disease-free planting material.

16. What are biofertilizers? Give examples.

    Living microbial preparations that enrich soil nutrients. Examples: Rhizobium (N2-fixation in legume root nodules), Azotobacter and Azospirillum (free-living/associative N-fixers), Anabaena/Azolla (cyanobacteria in rice), and mycorrhizae (phosphorus uptake).

17. How is biodiversity used as a resource (bioprospecting)?

    Bioprospecting screens biodiversity for useful genes, molecules and organisms—yielding new drugs and antibiotics, industrial enzymes from extremophiles, crop genes for resistance/quality, novel bioactive compounds, and biomimetic designs.

18. What is germplasm conservation and its two main strategies?

    Preservation of genetic diversity for future use. In situ: conservation in natural habitats (national parks, biosphere reserves). Ex situ: conservation outside habitat (gene/seed banks, cryopreservation, botanical gardens, in-vitro culture).

19. What is Marker-Assisted Selection (MAS)?

    A breeding approach that uses molecular markers tightly linked to a gene/QTL of interest to select desirable individuals at the DNA level (often as seedlings), instead of relying solely on phenotype.

20. What are the main advantages of Marker-Assisted Selection over conventional selection?

    Earlier selection (independent of environment and plant stage), accurate selection for traits hard to score phenotypically (disease resistance, quality), efficient gene pyramiding, faster recovery of recurrent parent genome in backcrossing, and reduced breeding time.

21. Name common molecular marker types used in MAS.

    RFLP, RAPD, AFLP, SSR/microsatellites, and SNPs. SSRs and SNPs are most widely used today due to abundance, co-dominance (SSR) and amenability to high-throughput genotyping (SNP).

22. What is bioremediation?

    The use of living organisms—mainly microorganisms (and plants)—to degrade, detoxify, transform, or remove environmental pollutants such as hydrocarbons, pesticides, and heavy metals from soil, water, or air.

23. Differentiate in situ and ex situ bioremediation.

    In situ treats the contaminant at the site without excavation (e.g., bioventing, biosparging, bioaugmentation, biostimulation). Ex situ removes contaminated material for treatment elsewhere (e.g., landfarming, composting, bioreactors/slurry phase).

24. What is phytoremediation and name its major mechanisms?

    Use of plants to clean up contaminated soil/water. Mechanisms: phytoextraction (accumulation in harvestable tissues), phytodegradation (breakdown within plant), rhizofiltration (root absorption from water), phytostabilization (immobilizing pollutants), phytovolatilization (release as vapour), and rhizodegradation (microbial breakdown in rhizosphere).

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