Unit 5: Applications of Biotechnology

Developing crops that are naturally resistant to pests reduces the reliance on chemical pesticides. Bt-cotton is the most prominent example of this technology.

Mechanism of Action

• Source: The gene is derived from the soil bacterium Bacillus thuringiensis.
• The Cry Gene: This bacterium produces specific Cry proteins (crystal proteins) which are toxic to certain insect larvae (Lepidopterans like bollworms).
• Transformation: The cry gene is inserted into the cotton genome using Agrobacterium-mediated transfer.
• Toxicity: When an insect ingests the plant tissue, the alkaline environment of the insect's midgut activates the protoxin into a functional toxin. This toxin creates pores in the gut wall, leading to the insect's death.

Herbicide resistance allows farmers to spray fields with broad-spectrum herbicides to kill weeds without damaging the crop.

RoundUp Ready Soybean

• Target: These plants are resistant to Glyphosate, the active ingredient in the herbicide "RoundUp".
• The Mechanism: Glyphosate normally kills plants by inhibiting the enzyme EPSPS, which is essential for synthesizing aromatic amino acids.
• The Solution: A glyphosate-resistant version of the EPSPS gene (from the CP4 strain of Agrobacterium) is inserted into the soybean plant.
• Outcome: The plant can still produce necessary amino acids even in the presence of the herbicide.

Biotechnology is used to enhance the nutritional value or shelf-life of food crops.

A. Flavr Savr Tomato

• Objective: To increase shelf-life and improve flavor by delaying ripening.
• Mechanism: Use of Antisense RNA technology to block the production of the enzyme Polygalacturonase (PG). PG is responsible for breaking down pectin in cell walls, which causes softening.
• Result: The tomatoes remain firm for a longer period, allowing them to ripen on the vine for better flavor without spoiling during transport.

B. Golden Rice

• Objective: To combat Vitamin A deficiency in developing nations.
• Mechanism: Rice is genetically engineered to produce beta-carotene (a precursor to Vitamin A) in the endosperm.
• The Genes: Two genes from daffodils (Narcissus pseudonarcissus) and one gene from a bacterium (Erwinia uredovora) were inserted into the rice genome.

Horticulture benefits from biotechnology through the creation of novel colors and longer-lasting flowers.

Moondust Carnations

• Innovation: The world's first genetically modified "blue" or violet carnations.
• Genetic Modification: Carnations lack the blue pigment Delphinidin. Scientists inserted genes for the enzymes Flavonoid 3',5'-hydroxylase (from petunias) to complete the blue pigment pathway.

Bioremediation is the use of organisms to clean up environmental pollutants.

The "Superbug"

• Creator: Developed by Dr. Ananda Mohan Chakrabarty.
• Organism: A genetically engineered strain of Pseudomonas putida.
• Function: It contains multiple plasmids that allow it to degrade different components of crude oil (hydrocarbons).
• Significance: It can be used to treat massive oil spills in the ocean much more effectively than natural bacteria.

Plants can be used as "bioreactors" to produce pharmaceuticals and vaccines for human health.

Edible Vaccines

• Concept: Inserting genes for disease-specific antigens into edible plants like potatoes, bananas, or tomatoes.
• Mechanism: When the fruit/vegetable is eaten, the immune system recognizes the antigens and produces antibodies, providing immunity.
• Advantage: No needles required, easier storage (no cold chain needed), and low cost for mass vaccination.

Genetically Engineered Products

• Humulin: The first genetically engineered human insulin, produced by inserting the human insulin gene into E. coli. This replaced the use of bovine or porcine insulin, which caused allergic reactions.
• Human Growth Hormone (HGH): Produced through recombinant DNA technology to treat growth disorders.

Despite the benefits, the use of Genetically Modified Organisms (GMOs) raises several ethical, environmental, and health concerns.

• Ecological Risks: Fear of "superweeds" created by cross-pollination between transgenic crops and wild relatives. Potential harm to non-target insects (e.g., monarch butterflies and Bt-toxin).
• Human Health Risks: Concerns about potential allergens or unexpected toxins in GM foods. Transfer of antibiotic resistance genes to gut bacteria.
• Ethical and Economic Issues: Corporate control over the food supply through patents on life forms. Intellectual Property Rights (IPR) issues for small-scale farmers.

8. Exam Focus: Tips and FAQs

Common Mistakes

• Mistake: Assuming Golden Rice is meant to increase protein. Correction: It is specifically for Vitamin A (beta-carotene) enrichment.
• Mistake: Thinking the "Superbug" is a virus. Correction: It is a bacterium (Pseudomonas putida).

Frequently Asked Questions

Q: What is the benefit of Antisense RNA technology in tomatoes?
A: It "silences" the gene responsible for cell wall softening, allowing the fruit to stay firm longer while ripening on the plant.

Q: Why is "Humulin" safer than animal-derived insulin?
A: It is identical to human insulin, meaning it does not trigger the immune system's "foreign protein" response like pig or cow insulin did.