Biotechnology and its Applications: Study Notes Class 12 Biology CBSE CHSE

Biotechnology is the use of genetically modified organisms (GMOs)—microbes, fungi, plants, and animals—to produce products and processes beneficial to humans, primarily in the fields of therapeutics, diagnostics, and agriculture.

I. Biotechnological Applications in Agriculture

The main goal is to create Genetically Modified Organisms (GMOs) to increase food production and reduce reliance on chemical agents.

Genetically Modified Organisms (GMOs):

Plants, bacteria, fungi, or animals whose genes have been altered by introducing a foreign gene.

Advantages of GMOs:

Crops are more tolerant to abiotic stresses (heat, cold, drought, salt).

Production of pest-resistant crops (less reliance on chemical pesticides).

Reduced post-harvest losses.

Increased efficiency of mineral uptake.

Enhanced nutritional value (e.g., Golden Rice rich in Vitamin A, a precursor to β-carotene).

 

Pest-Resistant Plants (Bt Crops):

 

Source: Gene isolated from the bacterium Bacillus thuringiensis (Bt).

Mechanism (e.g., Bt Cotton):

The Bt gene (e.g., cryIAb or cryIAc) codes for an inactive protoxin (crystal protein or Cry protein).

When an insect (like a bollworm) ingests the plant part, the alkaline pH in the insect's gut activates the protoxin, converting it into an active toxin.

The active toxin binds to the surface of the midgut epithelial cells, creating pores that cause cell swelling, lysis, and ultimately, the death of the insect.

Note: The toxin does not harm humans because the human gut is acidic, which prevents the activation of the protoxin.

RNA Interference (RNAi) in Pest Control:

Application: Used to make tobacco plants resistant to the nematode Meloidogyne incognita, which infects roots.

Mechanism: Using an Agrobacterium vector, nematode-specific genes are introduced into the host plant. This DNA produces both sense and anti-sense RNA inside the plant cell.

The sense and anti-sense RNAs anneal to form a double-stranded RNA (dsRNA).

This dsRNA initiates RNAi, which silences the specific mRNA of the nematode, preventing the synthesis of essential proteins and causing the parasite's death.

II. Biotechnological Applications in Medicine

Recombinant DNA technology allows the mass production of safe and effective therapeutic drugs.

Genetically Engineered Insulin (Humulin):

Problem: Earlier, insulin from animal sources (pigs, cattle) often caused allergic reactions.

Solution: Human insulin consists of two short polypeptide chains, A and B, linked by disulphide bridges.

In 1983, an American company, Eli Lilly, prepared two DNA sequences corresponding to the A and B chains and introduced them separately into plasmids of E. coli.

The chains were produced separately, extracted, and then chemically combined in vitro to form functional human insulin (Humulin).

Gene Therapy:

Definition:

Correction of a gene defect by inserting a normal gene into an individual's cells or tissues to replace the non-functional one.

First Clinical Gene Therapy:

Performed in 1990 for a 4-year-old girl with

Adenosine Deaminase (ADA) deficiency

.

ADA Deficiency:

Caused by the deletion of the gene for ADA, which is essential for the function of the immune system.

Treatment Options:

Enzyme Replacement Therapy:

Periodic injection of the functional ADA enzyme (not a complete cure).

Bone Marrow Transplantation:

Requires a suitable donor (not a complete cure).

Gene Therapy (Permanent Cure):

Isolation of the ADA gene from lymphocytes, insertion of the functional ADA cDNA into lymphocytes

using a retroviral vector, and returning the engineered cells to the patient. If the gene is introduced into the cells at an

early embryonic stage

, it is a permanent cure.

Molecular Diagnosis:

Detection of diseases (like AIDS or cancer) when symptoms are not yet visible (very low concentration of pathogen/mutant gene).

Techniques:

PCR (Polymerase Chain Reaction):

Used to amplify specific DNA/RNA segments from a sample. Detects pathogens (e.g., HIV) in minute quantities early in infection.

ELISA (Enzyme-Linked Immunosorbent Assay):

Based on the

antigen-antibody interaction

. Used to detect the presence of antigens (pathogen proteins) or antibodies synthesized against the pathogen.

III. Transgenic Animals

Animals whose genome has been modified to possess and express a foreign gene. Transgenic mice are the most common (over 95%).

Primary Purposes of Transgenic Animals:

Study of Normal Physiology and Development: To study gene regulation, and the role of genes in body functions (e.g., growth factors).

Study of Disease: To serve as models for human diseases (e.g., cancer, Alzheimer's, cystic fibrosis) to investigate new treatments.

Biological Products: Production of useful biological products (Molecular Farming).

Example: Rosie (1997), the first transgenic cow, produced milk enriched with human α-lactalbumin (2.4 grams per liter). This milk was nutritionally more balanced for human babies than natural cow milk.

Vaccine Safety Testing: Used to test the safety of vaccines before human trials (e.g., Polio vaccine).

Chemical Safety Testing (Toxicity Testing): Transgenic animals (more sensitive to toxic substances) are used to test the safety of drugs and chemicals.

IV. Ethical Issues and Biopiracy

Ethical Concerns: The manipulation of living organisms raises ethical questions regarding its morality and potential unpredictable risks to the ecosystem.

GEAC (Genetic Engineering Approval Committee): An Indian government organization that makes decisions on the validity of GM research and the safety of introducing GM-organisms for public use.

Biopiracy: The term used to refer to the use of bio-resources and traditional knowledge belonging to a country or indigenous people by multinational companies and others without proper authorization and compensatory payment.

Examples: Patenting of the anti-fungal properties of Neem, wound-healing properties of Turmeric, and the varieties/genetic material of Basmati Rice.