GATE Biotechnology Plant, Animal and Microbial Biotechnology Syllabus

Plant, Animal and Microbial Biotechnology syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Plant, Animal and Microbial Biotechnology in GATE Biotechnology, not a summary of it.

1. 1

   Plants

   11 topics

   • Totipotency
   • Regeneration of plants
   • Plant growth regulators and elicitors
   • Tissue culture and cell suspension culture system
     • Methodology
     • Kinetics of growth
     • Nutrient optimization
   • Production of secondary metabolites
   • Hairy root culture
   • Plant products of industrial importance
   • Artificial seeds
   • Somaclonal variation
   • Protoplast, protoplast fusion
     • Somatic hybrid
     • Cybrid
   • Transgenic plants
     • Direct and indirect methods of gene transfer techniques
     • Selection marker and reporter gene
     • Plastid transformation
2. 2

   Animals

   10 topics

   • Culture media composition and growth conditions
   • Animal cell and tissue preservation
   • Anchorage and non-anchorage dependent cell culture
   • Kinetics of cell growth
   • Micro & macro-carrier culture
   • Hybridoma technology
   • Stem cell technology
   • Animal cloning
   • Transgenic animals
   • Knock-out and knock-in animals
3. 3

   Microbes

   4 topics

   • Production of biomass and primary/secondary metabolites
     • Biofuels
     • Bioplastics
     • Industrial enzymes
     • Antibiotics
   • Large scale production and purification of recombinant proteins and metabolites
   • Clinical, food and industrial microbiology
   • Screening strategies for new products

Plant, Animal and Microbial Biotechnology flashcards for GATE Biotechnology

23 of 50 cards from the Plant, Animal and Microbial Biotechnology deck — real questions with worked answers.

1. Define totipotency in the context of plant tissue culture.

   Totipotency is the inherent capacity of a single plant cell to divide, differentiate, and regenerate into a complete, whole organism when provided with appropriate nutrients and growth conditions. It was first conceptualized by Haberlandt and demonstrated by F.C. Steward using carrot phloem cells.

2. Distinguish between organogenesis and somatic embryogenesis as routes of plant regeneration.

   Organogenesis is the de novo formation of organs (shoots/roots) from a callus or explant via unipolar structures connected to parent tissue. Somatic embryogenesis is the formation of bipolar embryo-like structures (with both shoot and root poles) from somatic cells, which have no vascular connection to the maternal tissue.

3. In Skoog and Miller's classic experiment, what determines whether a tobacco callus forms shoots or roots?

   The auxin-to-cytokinin ratio. A high cytokinin:auxin ratio promotes shoot formation, a high auxin:cytokinin ratio promotes root formation, and an intermediate/balanced ratio favors callus (undifferentiated) growth.

4. Name the five major classes of plant growth regulators and one representative of each.

   Auxins (IAA, 2,4-D, NAA), Cytokinins (kinetin, BAP, zeatin), Gibberellins ($\text{GA}_{3}$), Abscisic acid (ABA), and Ethylene. (Newer groups include brassinosteroids and jasmonates.)

5. What are elicitors and why are they used in plant cell culture?

   Elicitors are biotic (fungal/bacterial cell-wall fragments, chitosan, yeast extract) or abiotic (heavy metals, UV, osmotic stress) agents that trigger the plant's defense response, thereby stimulating and enhancing the production of secondary metabolites in cell/tissue cultures.

6. What is the composition basis of Murashige and Skoog (MS) medium that makes it widely used?

   MS medium (1962) is characterized by its high concentration of inorganic nitrogen, supplied as both nitrate ($\ce{NO3-}$) and ammonium ($\ce{NH4+}$), plus a complete set of macro- and micronutrients, vitamins, a carbon source (sucrose), and growth regulators. It supports rapid growth of most species.

7. Differentiate callus culture from cell suspension culture.

   Callus culture is an unorganized, undifferentiated mass of cells grown on a solid (agar-gelled) medium. Cell suspension culture consists of single cells and small cell aggregates dispersed and growing in an agitated liquid medium, allowing more uniform growth and easier scale-up.

8. List the typical phases of a batch suspension culture growth curve.

   Lag phase, exponential (log) phase, linear phase, deceleration (progressive deceleration) phase, and stationary phase. (A death/decline phase may follow.)

9. Define the specific growth rate $\mu$ and give the equation for exponential cell growth.

   The specific growth rate $\mu$ is the rate of biomass increase per unit biomass. Exponential growth follows $$\frac{dX}{dt} = \mu X \quad\Rightarrow\quad X_{t} = X_{0}e^{\mu t}$$ where $X$ is biomass concentration.

10. How is the doubling time $t_{d}$ related to the specific growth rate $\mu$?

    $$t_{d} = \frac{\ln 2}{\mu} = \frac{0.693}{\mu}$$ It is the time required for the biomass to double during exponential growth.

11. State the Monod equation relating specific growth rate to limiting substrate concentration.

    $$\mu = \frac{\mu_{max} S}{K_{s} + S}$$ where $\mu_{max}$ is the maximum specific growth rate, $S$ is the limiting substrate concentration, and $K_{s}$ is the substrate (half-saturation) constant, the value of $S$ at which $\mu = \tfrac{1}{2}\mu_{max}$.

12. Define the biomass yield coefficient $Y_{X/S}$.

    It is the mass of cells (biomass) produced per unit mass of substrate consumed: $$Y_{X/S} = \frac{-\Delta X}{\Delta S}$$ A measure of how efficiently substrate is converted into cell material.

13. In a chemostat (continuous culture) at steady state, how does the specific growth rate relate to the dilution rate?

    At steady state $\mu = D$, where the dilution rate $D = \dfrac{F}{V}$ (flow rate $F$ divided by culture volume $V$). Washout occurs when $D$ exceeds $\mu_{max}$.

14. What is nutrient optimization in cell suspension culture aimed at, and name two strategies.

    It aims to maximize biomass and/or product (secondary metabolite) yield by adjusting medium components. Strategies include altering the carbon source/sucrose level, optimizing the nitrate:ammonium ratio, phosphate limitation, and using a two-stage culture (growth medium then production medium).

15. Why are secondary metabolites often produced in a growth-dissociated manner, and how is this exploited industrially?

    Many secondary metabolites accumulate during the stationary/idiophase rather than the growth phase. This is exploited with a two-stage (two-medium) strategy: first a growth-optimized medium to build biomass, then a production-optimized medium (often with elicitors, precursors, or stress) to maximize metabolite synthesis.

16. What is hairy root culture and which organism induces it?

    Hairy root culture is a transformed root culture induced by infection with Agrobacterium rhizogenes. Transfer of the Ri (root-inducing) plasmid T-DNA causes fast-growing, highly branched, genetically stable roots that grow on hormone-free medium and are excellent for stable secondary metabolite production.

17. Compare the Ti plasmid of A. tumefaciens with the Ri plasmid of A. rhizogenes in terms of the phenotype they induce.

    The Ti (tumor-inducing) plasmid of Agrobacterium tumefaciens induces crown gall tumors (callus/teratomas). The Ri (root-inducing) plasmid of Agrobacterium rhizogenes induces hairy roots. Both transfer T-DNA into the plant genome.

18. Give three plant-derived products of industrial/pharmaceutical importance and their source plants.

    Examples: Shikonin (dye/antimicrobial) from Lithospermum erythrorhizon; Taxol/paclitaxel (anticancer) from Taxus species; Vinblastine/vincristine (anticancer) from Catharanthus roseus; Berberine (alkaloid) from Coptis japonica.

19. What are artificial (synthetic) seeds and how are they typically produced?

    Artificial seeds are somatic embryos (or shoot buds) encapsulated in a protective, nutritive gel coat. They are commonly made by suspending somatic embryos in sodium alginate and dropping it into a calcium chloride ($\ce{CaCl2}$) solution to form calcium-alginate beads (ion-exchange gelation).

20. Define somaclonal variation and state its main cause.

    Somaclonal variation is the genetic and phenotypic variation observed among plants regenerated from cultured somatic cells/calli. It arises from culture-induced changes such as chromosomal rearrangements, point mutations, ploidy changes, transposon activation, and epigenetic alterations.

21. What is gametoclonal variation, and how does it differ from somaclonal variation?

    Gametoclonal variation is the variation observed among plants regenerated from cultured gametic (haploid) cells such as microspores or pollen (e.g., via anther culture). It differs from somaclonal variation, which arises from somatic (diploid) tissue cultures.

22. What is a protoplast and how is it conventionally prepared?

    A protoplast is a plant cell from which the cell wall has been completely removed, leaving only the plasma-membrane-bound cell. It is prepared enzymatically by digesting the wall with cellulase, hemicellulase, and pectinase in an osmotically stabilized (e.g., mannitol/sorbitol) medium.

23. Name two widely used methods of inducing protoplast fusion.

    Chemical fusion using polyethylene glycol (PEG), often with high pH/high $\ce{Ca^2+}$; and electrofusion, where an electric field aligns protoplasts (dielectrophoresis) and a DC pulse fuses their membranes.

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