Complete Biology notes on Biotechnology: GM Crops, DNA  and Cloning  for BPSC and Other Competitive Exams in 2025

Complete Biology notes on Biotechnology: GM Crops, DNA  and Cloning  for BPSC and Other Competitive Exams in 2025

General Science- 21 (Biology)

Here’s a detailed explanation of Biotechnology, focusing on GM Crops, DNA, and an introduction to Cloning.

Biotechnology: GM Crops, DNA, Cloning

Biotechnology is a rapidly advancing field that harnesses biological processes, organisms, or systems to produce products or technologies to improve human lives.

1. Introduction to Biotechnology

• Definition: Biotechnology is the use of living organisms or their derivatives to develop or make products or processes for a specific use. It integrates natural sciences and engineering sciences to achieve the application of organisms, cells, parts thereof and molecular analogues for products and services.
• Scope: It’s an interdisciplinary field that combines biology (especially molecular biology, genetics, microbiology) with chemistry, engineering, and computer science.
• Applications: Biotechnology has vast applications across various sectors, including:
  • Medicine: Production of vaccines, insulin, antibiotics, gene therapy, diagnostics.
  • Agriculture: Development of genetically modified (GM) crops for improved yield and resistance.
  • Industry: Biofuels, enzymes, fermented products.
  • Environment: Bioremediation (using microbes to clean up pollution).

2. DNA (Deoxyribonucleic Acid) – The Foundation of Biotechnology

DNA is the molecule that carries the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms and many viruses. It is the central pillar around which much of modern biotechnology revolves.

• Structure: DNA typically exists as a double helix, resembling a twisted ladder. This structure was famously discovered by Watson and Crick in 1953, based on Rosalind Franklin’s X-ray diffraction data.
  • Each strand of the helix is made up of a long chain of repeating units called nucleotides.¹¹
  • Each nucleotide consists of three parts:
    1. A deoxyribose sugar molecule.
    2. A phosphate group.
    3. One of four nitrogenous bases: Adenine (A), Thymine (T), Guanine (G), Cytosine (C).
  • The two strands of the double helix are held together by weak hydrogen bonds between the bases, following specific base pairing rules: Adenine (A) always pairs with Thymine (T), and Guanine (G) always pairs with Cytosine (C).
• Function:
  • Genetic Information Carrier: DNA stores all the hereditary information of an organism, acting as the “blueprint” for building and maintaining an organism.
  • Protein Synthesis: The sequence of bases in DNA codes for the production of proteins, which perform most of the work in cells and are required for the structure, function, and regulation of the body’s tissues and organs.
  • Heredity: DNA is accurately copied and passed from parents to offspring, ensuring the transmission of genetic traits across generations.
• Relevance to Biotechnology: The ability to understand, manipulate, and transfer specific DNA sequences is at the core of genetic engineering and many biotechnological applications, allowing scientists to alter the traits of organisms.

3. Genetically Modified (GM) Crops

GM crops (also known as transgenic crops or genetically engineered crops) are plants used in agriculture whose DNA has been modified using genetic engineering techniques.This modification aims to introduce new traits that are not naturally present in the species.

• Definition: GM crops are plants whose genetic material has been altered in a way that does not occur naturally by mating and/or natural recombination. It involves inserting specific genes from another organism (could be bacteria, virus, or another plant species) into the plant’s genome.
• Process (Simplified):
  1. Identification of a desired gene: For example, a gene that confers pest resistance.
  2. Isolation of the gene: Cutting out the specific gene from the donor organism’s DNA using enzymes.
  3. Insertion into plant DNA: The isolated gene is then inserted into the DNA of the plant cells, often using a “gene gun” or bacterial vectors (like Agrobacterium tumefaciens).
  4. Regeneration: The genetically modified plant cells are then grown in tissue culture to regenerate into whole plants.
  5. Selection: Plants that successfully express the new trait are selected and propagated.
• Common Traits Introduced in GM Crops:

• Herbicide Resistance: Crops are made resistant to specific herbicides, allowing farmers to spray herbicides to kill weeds without harming the crop. (e.g., Roundup Ready Soybeans, resistant to glyphosate).
• Pest Resistance: Crops are engineered to produce toxins that kill specific insect pests, reducing the need for chemical pesticides. (e.g., Bt Cotton, Bt Brinjal – contains genes from the bacterium Bacillus thuringiensis that produce proteins toxic to certain insect larvae).
• Improved Nutritional Value: Enhancing the nutrient content of crops. (e.g., Golden Rice – engineered to produce beta-carotene, a precursor to Vitamin A, to combat Vitamin A deficiency).
• Disease Resistance: Making crops resistant to viral, bacterial, or fungal diseases.
• Enhanced Shelf Life / Drought Tolerance / Salinity Tolerance: Other desirable traits.
• Advantages of GM Crops:

• Increased Yield: Can lead to higher productivity per unit area.
• Reduced Pesticide Use: Especially with pest-resistant varieties, leading to environmental benefits and lower input costs for farmers.
• Improved Nutritional Content: Addressing malnutrition in developing countries.
• Tolerance to Environmental Stresses: Developing crops that can withstand drought, salinity, etc.
• Reduced Food Waste: Crops with longer shelf life.
• Concerns/Controversies:

• Environmental Impact: Potential for gene flow to wild relatives (creating “superweeds”), impact on non-target insects (like beneficial pollinators), reduction in biodiversity.
• Health Concerns: Potential for allergic reactions, toxicity, or unforeseen long-term effects on human health (though extensive studies by regulatory bodies often deem approved GM crops safe).
• Ethical and Socio-economic Issues: Corporate control over seeds, impact on traditional farming practices, labeling requirements, consumer choice.
• Status in India:

• Bt Cotton: The only GM crop officially approved for commercial cultivation in India (since 2002), and it is widely adopted.
• Bt Brinjal: Approved by regulatory body (GEAC) in 2009 but its commercial release was put on an indefinite moratorium by the government due to public opposition and safety concerns.
• GM Mustard (DMH-11): Recently received environmental clearance for commercial cultivation in 2022, but its actual commercial release is still facing legal challenges and public debate.

4. Cloning

Cloning, in biology, refers to the process of producing genetically identical copies of a biological entity. This can range from a single gene to an entire organism.

• Definition: The creation of an exact genetic replica of a cell, tissue, or an entire organism. The genetic information of the clone is identical to the original.
• Types of Cloning (Introductory overview):
  1. Gene Cloning (DNA Cloning):
     • Purpose: To produce multiple, identical copies of a specific gene or a segment of DNA.
     • Process (simplified): A piece of DNA containing the gene of interest is inserted into a small, circular piece of DNA called a plasmid (from bacteria). This recombinant plasmid is then introduced into a bacterial cell, which replicates the plasmid along with its own DNA, producing many copies of the inserted gene.
     • Applications: Widely used in research (e.g., studying gene function), biotechnology (e.g., producing large quantities of specific proteins like insulin, growth hormone), and gene therapy.
  2. Reproductive Cloning:
     • Purpose: To create a genetically identical copy of an entire multicellular organism.
     • Famous Example: Dolly the sheep (1996) was the first mammal successfully cloned from an adult somatic cell by Ian Wilmut and Keith Campbell at the Roslin Institute in Scotland.
     • Process (Simplified – Somatic Cell Nuclear Transfer – SCNT):
       1. A somatic cell (any body cell other than a sperm or egg cell, e.g., a skin cell) is taken from the animal to be cloned.
       2. An unfertilized egg cell is taken from a donor animal, and its nucleus (containing genetic material) is removed (enucleated).
       3. The nucleus from the somatic cell is then transferred into the enucleated egg cell.
       4. The reconstructed egg cell is stimulated (e.g., with an electric pulse) to begin dividing and developing into an embryo.
       5. This embryo is then implanted into the uterus of a surrogate mother.
       6. If successful, the surrogate mother gives birth to an offspring that is genetically identical to the animal from which the somatic cell was taken.
     • Ethical Concerns: Reproductive cloning of humans is universally considered highly unethical and is legally banned in many countries due to concerns about human dignity, identity, potential for abuse, and safety issues (high failure rate, health problems in cloned animals).
  3. Therapeutic Cloning:
     • Purpose: To create cloned embryos for the sole purpose of harvesting embryonic stem cells, which have the potential to develop into various cell types. These stem cells could then be used to treat diseases (e.g., Parkinson’s, Alzheimer’s, spinal cord injuries) by replacing damaged tissues.
     • Key Difference from Reproductive Cloning: The embryo is not implanted into a uterus to develop into a full organism; its development is stopped at an early stage to obtain stem cells.
     • Ethical Concerns: Still raises significant ethical debates, as it involves the creation and destruction of human embryos, though its purpose is therapeutic.

Practice Questions

1. Biotechnology primarily involves the use of:
   • A) Only dead organisms for industrial processes
   • B) Chemical synthesis exclusively
   • C) Living organisms or their products
   • D) Only physical methods for production
   • Rationale: Biotechnology leverages biological systems for various applications.
2. The double helix structure of DNA was famously discovered by:
   • A) Gregor Mendel
   • B) Watson and Crick
   • C) Louis Pasteur
   • D) Robert Hooke
   • Rationale: Watson and Crick are credited with proposing the double helix model of DNA.
3. In a DNA molecule, Adenine (A) always pairs with which nitrogenous base?
   • A) Guanine (G)
   • B) Cytosine (C)
   • C) Thymine (T)
   • D) Uracil (U)
   • Rationale: The specific base pairing rule for DNA is A with T, and G with C. Uracil (U) is found in RNA.

4. Genetically Modified (GM) crops are developed by altering their:
   • A) Protein structure through heating
   • B) Genetic material (DNA)
   • C) Cell wall composition
   • D) Water absorption capacity
   • Rationale: Genetic modification specifically involves manipulating the DNA of an organism.
5. Which of the following GM crops is widely cultivated in India for pest resistance?
   • A) Golden Rice
   • B) Bt Brinjal
   • C) GM Mustard
   • D) Bt Cotton
   • Rationale: Bt Cotton is the only GM crop widely grown commercially in India.
6. Golden Rice is a genetically modified crop engineered to be rich in:⁴⁶
   • A) Proteins
   • B) Iron
   • C) Vitamin A
   • D) Vitamin C
   • Rationale: Golden Rice was developed to combat Vitamin A deficiency by producing beta-carotene.
7. The ‘Bt’ in Bt Cotton refers to a gene derived from which organism?
   • A) A plant virus
   • B) A type of fungus
   • C) A specific insect pest
   • D) A bacterium (Bacillus thuringiensis)
   • Rationale: The Bt gene comes from the bacterium Bacillus thuringiensis and produces a protein toxic to certain insect pests.

8. The process of creating a genetically identical copy of an entire organism is known as:
   • A) Gene therapy
   • B) Genetic engineering
   • C) Reproductive cloning
   • D) Artificial selection
   • Rationale: Reproductive cloning aims to create a whole organism identical to the parent.
9. Dolly the sheep, the first mammal successfully cloned from an adult somatic cell, was created using which technique?
   • A) In vitro fertilization
   • B) Artificial insemination
   • C) Somatic Cell Nuclear Transfer (SCNT)
   • D) Gene splicing
   • Rationale: SCNT was the breakthrough technique used to clone Dolly.
10. In gene cloning, a specific gene segment is often inserted into a small, circular piece of DNA from bacteria called a:
    • A) Nucleus
    • B) Chromosome
    • C) Plasmid
    • D) Ribosome
    • Rationale: Plasmids are commonly used as vectors in gene cloning to carry and replicate foreign DNA.