Microorganisms and Viruses

Microorganisms Overview

  • Microorganisms are tiny organisms only visible under a microscope.

    • Sizes:

      • Typical animal cells: ~100 μm

      • Bacterial cells: ~1 μm

      • Viruses: 10x smaller than bacteria.

  • Found in various environments, including extreme conditions.

  • Pathogens: harmful microorganisms that can cause disease.

Major Groups of Microorganisms

  • Four main types:

    1. Bacteria

    2. Viruses

    3. Fungi

    4. Protozoa

Immune System and Pathogens

  • Natural barriers: skin, mucous membranes, stomach acid, etc.

  • Immune system uses white blood cells and antibodies to fight pathogens.

  • Mucous membranes filter airborne microorganisms.

Viruses

  • Composed of nucleic acid (RNA or DNA) and a protein coat (capsid).

  • Acellular structures, not included in the tree of life.

  • Enveloped vs. non-enveloped virus types:

    • Enveloped: has a lipid layer.

    • Naked: consists of only nucleic acid and capsid.

  • Cannot replicate independently; must infect host cells.

Viral Infection and Transmission

  • Viruses are host-specific and can cause various diseases.

  • Spread can occur via surfaces, highlighting the importance of hygiene.

Viral Reproduction

  • Process involves entering host cells and replicating.

  • Budding (for enveloped viruses) or lysis (for non-enveloped viruses) to exit the host cell.

Vaccination and Immune Response

  • Vaccines prepare the immune system to recognize and fight pathogens.

  • They contain weakened or killed pathogens or non-infectious virus components.

  • Vaccination can prevent infections or lessen their severity.

  • Some pathogens mutate, complicating immunity for future infections.