Biology (4BI1)
Topic 17 of 18Pearson EdExcel

Biotechnology and Genetic Engineering

Using organisms and their components to create useful products and processes.

### Introduction to Biotechnology


Biotechnology is a broad field that uses living organisms, cells, or their components to develop technologies and products that help improve our lives. While it sounds modern, humans have used biotechnology for millennia in processes like baking, brewing, and cheese making. Modern biotechnology, however, often involves the direct manipulation of an organism's genetic material, a field known as genetic engineering.


### Traditional Biotechnology: Use of Microorganisms


Microorganisms like bacteria and fungi are workhorses in traditional biotechnology, primarily through the process of fermentation. Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In the context of biology, it often refers to anaerobic respiration.


* Baking and Brewing: Yeast, a single-celled fungus, is essential. In baking, it performs anaerobic respiration to break down sugars in the dough, producing carbon dioxide gas which causes the bread to rise. In brewing, yeast ferments sugars in grains to produce ethanol (alcohol) and carbon dioxide.

The general equation for yeast fermentation is:

C₆H₁₂O₆ (Glucose) → 2C₂H₅OH (Ethanol) + 2CO₂ (Carbon Dioxide)


* Yoghurt Production: Bacteria such as *Lactobacillus* are added to milk. These bacteria respire anaerobically, converting the sugar in milk (lactose) into lactic acid. The lactic acid lowers the pH of the milk, causing the milk proteins to denature and coagulate (thicken), which gives yoghurt its characteristic texture and sour taste.


* Antibiotic Production: Some microorganisms naturally produce chemicals to kill competing microbes. We harness this ability to create antibiotics. For example, the fungus _Penicillium_ produces the antibiotic penicillin, which was the first to be discovered and is used to treat bacterial infections.


### Selective Breeding (Artificial Selection)


Long before understanding genetics, humans manipulated the characteristics of plants and animals through selective breeding. This is the process where humans choose organisms with desirable traits and breed them together to enhance those traits in subsequent generations.


The process of selective breeding involves:

  • Selection: From a mixed population, individuals with the desired characteristics are chosen (e.g., cows that produce the most milk, or wheat plants that are resistant to a fungal disease).
  • Breeding: These selected individuals are bred with each other.
  • Repetition: The offspring are observed, and only those with the desired characteristics are selected for further breeding. This process is repeated over many generations.

    • Examples include the development of high-yield wheat and rice varieties, domestic dog breeds, and cattle bred for high milk or meat production. The main drawback is that it can lead to a reduction in the gene pool, making the population more susceptible to new diseases.


    ### Genetic Engineering: Principles and Processes


    Genetic engineering offers a more precise and rapid way to alter an organism's traits by directly modifying its DNA. It allows for the transfer of genes between different species, which is not possible through selective breeding. The organism created is known as a Genetically Modified Organism (GMO).


    The core process of genetic engineering involves several key steps:

  • Gene Isolation: The desired gene is identified and isolated from the donor organism's DNA. This is achieved using restriction enzymes, which act like 'molecular scissors' to cut the DNA at specific recognition sites, leaving 'sticky ends'.
  • Vector Preparation: A vector is used to carry the isolated gene into the host cell. The most common vector is a plasmid – a small, circular piece of DNA found in bacteria. The same restriction enzyme is used to cut the plasmid open, creating complementary sticky ends.
  • Ligation: The isolated gene is inserted into the plasmid. An enzyme called DNA ligase acts as 'molecular glue', joining the gene and the plasmid together at their sticky ends. This new combined DNA molecule is called recombinant DNA.
  • Transformation: The recombinant plasmid is introduced into a host organism, typically a bacterium like *E. coli*. This uptake of foreign DNA is called transformation. Not all bacteria will successfully take up the plasmid, so marker genes (e.g., for antibiotic resistance) are often included to identify the transformed cells.
  • Cloning and Expression: The transformed bacteria are cultured in large industrial fermenters. As they multiply, they create millions of copies (clones) of the recombinant plasmid. The bacteria then express the inserted gene, producing the desired protein.

    • ### Applications of Genetic Engineering


    * Medicine: Genetically engineered bacteria are used to produce large quantities of human insulin for treating diabetes. Previously, insulin was extracted from pigs and cows, which was less effective and could cause allergic reactions. Vaccines, hormones, and other therapeutic proteins are also produced this way.

    * Agriculture: Crops are modified to enhance their traits. Genetically modified (GM) crops can be engineered for pest resistance, herbicide tolerance, drought resistance, or improved nutritional value (e.g., 'Golden Rice', which produces beta-carotene, a precursor to Vitamin A, to combat deficiency).

    Key Points to Remember

    • 1Biotechnology uses living organisms to create products; traditional forms include fermentation.
    • 2Microorganisms like yeast (baking, brewing) and bacteria (yoghurt) are used in fermentation.
    • 3Selective breeding is the artificial selection and breeding of organisms for desired traits over generations.
    • 4Genetic engineering is the direct manipulation of an organism's DNA to alter its characteristics.
    • 5The process uses restriction enzymes to cut DNA and DNA ligase to join a gene into a vector (plasmid), creating recombinant DNA.
    • 6Transformation is the introduction of this recombinant DNA into a host cell, such as a bacterium.
    • 7Key applications include the production of human insulin by bacteria and the creation of pest-resistant GM crops.
    • 8Recombinant DNA is a composite DNA molecule created by joining DNA from two different sources.

    Pakistan Example

    Bt Cotton in Pakistan's Agricultural Economy

    A prime example of genetic engineering in Pakistan is the widespread cultivation of **Bt cotton**. This is a genetically modified variety of cotton that contains a gene from the soil bacterium *Bacillus thuringiensis* (Bt). This gene produces a protein that is toxic to major cotton pests, particularly the pink bollworm, which causes significant crop damage. By growing Bt cotton, Pakistani farmers have been able to increase their yields, significantly reduce their reliance on expensive and environmentally harmful chemical pesticides, and boost the country's vital textile industry. It showcases how biotechnology provides a targeted solution to a major agricultural challenge.

    Quick Revision Infographic

    Biology — Quick Revision

    Biotechnology and Genetic Engineering

    Key Concepts

    1Biotechnology uses living organisms to create products; traditional forms include fermentation.
    2Microorganisms like yeast (baking, brewing) and bacteria (yoghurt) are used in fermentation.
    3Selective breeding is the artificial selection and breeding of organisms for desired traits over generations.
    4Genetic engineering is the direct manipulation of an organism's DNA to alter its characteristics.
    5The process uses restriction enzymes to cut DNA and DNA ligase to join a gene into a vector (plasmid), creating recombinant DNA.
    6Transformation is the introduction of this recombinant DNA into a host cell, such as a bacterium.
    Pakistan Example

    Bt Cotton in Pakistan's Agricultural Economy

    A prime example of genetic engineering in Pakistan is the widespread cultivation of **Bt cotton**. This is a genetically modified variety of cotton that contains a gene from the soil bacterium *Bacillus thuringiensis* (Bt). This gene produces a protein that is toxic to major cotton pests, particularly the pink bollworm, which causes significant crop damage. By growing Bt cotton, Pakistani farmers have been able to increase their yields, significantly reduce their reliance on expensive and environmentally harmful chemical pesticides, and boost the country's vital textile industry. It showcases how biotechnology provides a targeted solution to a major agricultural challenge.

    SeekhoAsaan.com — Free RevisionBiotechnology and Genetic Engineering Infographic
    Variation and EvolutionClassification of Living Organisms