Biotechnology and Its Applications: Class 12 NCERT Biology Guide

Introduction to Biotechnology and Its Applications

Biotechnology is the use of living organisms or their components to develop useful products. In Class 12 NCERT Biology, this chapter explains how biotechnology applies to agriculture, medicine, and industry. It focuses on genetic engineering, tissue culture, and microbial techniques that improve crop yield, disease resistance, and production of medicines.

Biotechnology helps solve real-world problems like pest control, food security, and health care. Understanding these applications prepares students for exams and practical knowledge.

Development of Pest-Resistant Plants Using Bt Genes

One of the most important applications of biotechnology in agriculture is producing pest-resistant plants. The bacterium Bacillus thuringiensis (Bt) produces insecticidal proteins that kill specific insect pests without harming other organisms.

• Bt produces crystal proteins (protoxins) that activate in the alkaline gut of insects.
• Activated Bt toxin binds to midgut cells, causing insect death.
• Bt toxin genes like cryIAc and cryIIAb are inserted into crops such as cotton, corn, and rice.

Example: Bt cotton expresses the cryIAc gene that controls cotton bollworms, a major pest. This reduces the need for chemical pesticides, increases crop yield, and lowers environmental pollution.

This method is eco-friendly and sustainable, making it a key biotechnology application.

Micropropagation: Rapid Multiplication of Plants

Micropropagation is a tissue culture technique used to produce many identical plants quickly. It is especially useful for producing disease-free plants.

• Uses small plant parts called explants, often from meristematic tissue.
• Explants are grown in vitro on nutrient media containing macronutrients, micronutrients, vitamins, carbon source (sucrose), and plant growth regulators (auxins and cytokinins).
• Results in rapid multiplication of genetically identical, virus-free plants.

Advantages:

• Produces large numbers of plants in a short time.
• Independent of seasonal changes.
• Helps conserve rare or endangered plants.

Medium Components:

• Macronutrients: Nitrogen, phosphorus, potassium
• Micronutrients: Iron, manganese, zinc
• Vitamins: Thiamine
• Carbon source: Sucrose
• Growth regulators: Auxins and cytokinins
• Gelling agent: Agar

This technique is widely used in horticulture and agriculture to meet commercial demands.

Meristem Culture for Virus-Free Plants

Meristem culture involves growing the apical meristem (the rapidly dividing tip of a plant shoot) in vitro to produce virus-free plants.

• Viruses do not invade meristematic tissue because of its rapid cell division.
• Plants regenerated from meristem culture are usually free from viruses.
• This technique is crucial for producing healthy planting material, especially in crops prone to viral infections.

Example: Virus-free sugarcane and potato plants are produced using meristem culture.

This method ensures high-quality planting stock and improves crop health and yield.

Transgenic Bacteria and Their Role in Biotechnology

Transgenic bacteria are genetically engineered to contain foreign genes from other organisms. They are important in producing medicines and enzymes.

• Example: Escherichia coli bacteria transformed with the human insulin gene produce insulin protein used to treat diabetes.
• These bacteria multiply rapidly, producing large quantities of the desired protein.

Advantages:

• Cost-effective production of hormones, vaccines, and enzymes.
• Reduces dependence on animal sources.

Transgenic bacteria are a cornerstone of modern biotechnology with vast medical and industrial applications.

Comparison of Traditional and Biotechnological Crop Improvement Methods

Understanding the differences between traditional breeding and biotechnological methods helps clarify biotechnology's advantages.

Biotechnology offers faster, targeted, and eco-friendly crop improvement.