Science Chapter 2: Microorganisms Found Everywhere

Microorganisms Found Everywhere

• Microorganisms are organisms that can't be seen with the naked eye and require a microscope to be visible.

Classification of Microorganisms

• Microorganisms can be classified into four groups:
• Bacteria: single-celled organisms, found in a wide range of habitats, and some are beneficial for the human body (e.g., Lactobacilli).
• Fungi: multicellular, heterotrophic organisms, lack chlorophyll, and are found on decaying organic matter (e.g., Penicillium, Aspergillus).
• Algae: unicellular or multicellular, autotrophic organisms, contain chlorophyll, and carry out photosynthesis (e.g., Chlorella, Spirogyra).
• Protozoa: unicellular or multicellular, usually found in water, and can be beneficial or harmful (e.g., Amoeba, Paramoecium).

Microorganisms and Us

• Some microorganisms are beneficial, while others cause diseases.
• Microorganisms can be used to preserve food through:
• Heat and cold treatments: pasteurization, boiling, and refrigeration.
• Storage and packing: using sealed packets to prevent microorganisms from entering.
• Chemical methods: using preservatives like common salt, sugar, oil, and vinegar.

Viruses

• Viruses: ultramicroscopic organisms that reproduce only inside the cells of host organisms (e.g., Influenza virus, Polio virus).

Where Do Microorganisms Live?

• Microorganisms can survive in all types of climates, from ice-cold to hot, and are found in water, soil, and inside the bodies of animals and humans.

Antibiotics

• Antibiotics: substances that kill or stop the growth of disease-causing microorganisms (e.g., Streptomycin, Tetracycline, Erythromycin).
• The first antibiotic, penicillin, was discovered by Alexander Fleming in 1929.

Vaccines

• Vaccines: substances that trigger the production of antibodies in the body, protecting against diseases.
• Vaccines include dead or weakened microbes, and the first vaccine was developed by Edward Jenner against smallpox in 1798.

Soil Fertility

• Biological nitrogen fixers: microorganisms like blue-green algae and Rhizobium bacteria that fix atmospheric nitrogen to soil, increasing soil fertility.

Importance of Microorganisms

• Food Industry: microorganisms like Lactobacillus and yeast are used to produce curd, bread, and pastries.
• Beverage Industry: yeast is used to produce alcohol, wine, and vinegar through fermentation.
• Medicine Production: microorganisms are used to produce antibiotics, which are used to kill or stop the growth of disease-causing microorganisms.

Human Diseases Caused by Microorganisms

• Tuberculosis: caused by bacteria, transmitted through air, and prevented by isolation and vaccination.
• Measles: caused by viruses, transmitted through air, and prevented by vaccination.
• Malaria: caused by protozoa, transmitted through mosquitoes, and prevented by vaccination and proper hygiene.
• Cholera: caused by bacteria, transmitted through water and food, and prevented by vaccination and proper hygiene.
• Typhoid: caused by bacteria, transmitted through water, and prevented by vaccination and proper hygiene.
• Hepatitis A: caused by viruses, transmitted through air and water, and prevented by vaccination.

Plant Diseases Caused by Microorganisms

• Citrus Canker: caused by bacteria, transmitted through air.
• Rust of wheat: caused by fungi, transmitted through air and seeds.
• Yellow vein mosaic of bhindi (Okra): caused by viruses, transmitted through insects.

Communicable Diseases

• Communicable diseases: diseases caused by microorganisms that spread from an infected person to a healthy person through air, water, and food.
• Carriers: organisms that transfer diseases from one place to another (e.g., houseflies, female Anopheles mosquitoes).