Biotechnology and its Applications

Biotechnology uses genetically modified organisms, cells and enzymes to make products useful to humans, and this chapter shows how the techniques of recombinant DNA technology are applied in agriculture and medicine. In agriculture you will study genetically modified crops such as Bt cotton, which carries cry genes from Bacillus thuringiensis that code for an inactive protoxin that becomes active in the alkaline gut of bollworm larvae, and pest-resistant tobacco plants protected from the nematode Meloidogyne incognita by RNA interference. In medicine you will learn how Eli Lilly produced human insulin in 1983 by preparing the A and B chains separately in E. coli and joining them by disulphide bonds, how gene therapy was first used in 1990 for a four-year-old girl with adenosine deaminase deficiency, and how PCR and ELISA allow early molecular diagnosis. The chapter also covers transgenic animals, such as the cow Rosie, and the ethical issues of biopiracy, patents on basmati rice, and the role of India's Genetic Engineering Approval Committee.

Detailed Worksheet: Biotechnology and its Applications Section A - Definitions (10 marks) 1. What are genetically modified organisms? State any two advantages of GM crops. (2 marks) 2. What is a Bt toxin? Why does it not kill the Bacillus thuringiensis bacterium that produces it? (2 marks) 3. Define RNA interference. In which organisms does it occur naturally as a defence mechanism? (2 marks) 4. What is gene therapy? Name the first disease treated by gene therapy and the year in which it was done. (2 marks) 5. Define biopiracy and biopatent. Give one Indian example related to biopiracy. (2 marks) Section B - Calculations and Applications (15 marks) 6. The A chain of human insulin has 21 amino acids and the B chain has 30 amino acids. Calculate the minimum number of nucleotides in the coding sequence (including the stop codon) needed to make each chain separately, as done by Eli Lilly. Why were the chains made separately? (3 marks) 7. A PCR reaction starts with 5 copies of a viral DNA segment. Assuming perfect doubling, calculate the number of copies after 10 cycles and after 20 cycles. Explain why this amplification is useful in diagnosing HIV infection at an early stage. (3 marks) 8. The transgenic cow Rosie produced human protein-enriched milk containing 2.4 grams of protein per litre. Calculate the amount of this protein in 15 litres of milk. Name the human protein and state why this milk was nutritionally better for human babies. (3 marks) 9. A farmer grows Bt cotton on 2 hectares and saves Rs 4,500 per hectare on insecticide sprays, but pays Rs 2,000 more per hectare for seeds. Calculate his net saving. State two possible ecological concerns about the large-scale use of Bt crops. (3 marks) 10. Identify the gene and the target pest in each case: (i) cryIAc and cryIIAb in cotton (ii) cryIAb in corn (iii) dsRNA of nematode-specific genes in tobacco. (3 marks) Section C - Diagrams (10 marks) 11. Draw a labelled flowchart showing how human insulin is produced by recombinant DNA technology, showing the separate A and B chain DNA sequences, their insertion into plasmids of E. coli, production of chains and joining by disulphide bonds. (4 marks) 12. Draw a labelled diagram showing the structure of mature human insulin with A chain, B chain and inter-chain disulphide bridges, and show how proinsulin differs by the presence of the C peptide. (3 marks) 13. Draw a flowchart showing how RNA interference was used to develop nematode-resistant tobacco plants, from introducing nematode genes through Agrobacterium to silencing of nematode mRNA. (3 marks) Section D - Analysis and Higher-order Thinking (15 marks) 14. Explain the mode of action of Bt toxin from the moment a bollworm larva ingests it to its death. Analyse why this mechanism makes Bt cotton specific to certain insects and safe for humans. (5 marks) 15. In 1990, a four-year-old girl with ADA deficiency was treated by gene therapy. Explain the procedure used, why the treatment was not a permanent cure, and what approach could give a permanent cure. Evaluate one ethical concern about gene therapy. (5 marks) 16. In 1997 an American company obtained patent rights on certain varieties of basmati rice derived from Indian farmers' varieties. Analyse why India objected, explain the meaning of biopiracy in this context, and suggest two measures India has taken to protect its biological resources. (5 marks) Instructions: Time allowed 2 hours. Attempt all sections. Draw all diagrams neatly in pencil and label every part. Use correct scientific names in italics form where needed (underline when handwriting).