Microbiology Overview Quiz

Microbes

• Microbes can be categorized as cellular and acellular.
• Cellular microbes include bacteria, archaea, fungi, and protists.
• Acellular microbes include viruses, prions, and viroids.

Normal Microbial Flora

• Normal microbial flora are permanent residents of the body.
• Found in areas like skin, mouth, nose, colon, and vagina.
• Composed of non-pathogenic bacteria and yeasts.
• Internal organs are sterile.

Scientific Nomenclature

• Carolus Linnaeus introduced the two-part naming system.
• First part is the genus, written with a capital letter.
• Second part is the species, written in lowercase.
• Both genus and species are written in italics.

History of Microbiology

• Antony van Leeuwenhoek - Invented the first microscope and observed microorganisms.
• Louis Pasteur - Known as the "Father of Microbiology".
  • Studied fermentation.
  • Introduced sterilization techniques.
  • Developed pasteurization.
  • Contributed to vaccine development.
  • Postulated the "germ theory of disease".
• Robert Koch - Known as the "Father of Bacteriology."
  • Received the Nobel Prize for discovering the tubercle bacilli.
  • Introduced solid media for culturing bacteria.
  • Developed methods for isolating bacteria in pure cultures.
  • Introduced staining techniques.
  • Described Koch's postulates and phenomenon.
• Edward Jenner - Known as the "Father of Immunology."
  • Developed the first vaccine for smallpox.
• Alexander Fleming - Discovered penicillin.
• Selman Waksman - Discovered streptomycin.
• Charles Chamberland - Discovered viruses and their role in disease.

Bacterial Structure

• Outer Membrane
  • Found only in Gram-negative bacteria.
  • Acts as a barrier.
  • Composed of lipopolysaccharide (LPS) and phospholipids.
  • LPS acts as an endotoxin, causing fever and shock.
• Peptidoglycan
  • A complex network surrounding the entire cell.
  • Provides structural support and maintains cell shape.
  • Found only in bacterial cell walls.
• Teichoic Acid
  • Found in the outer layer of Gram-positive cell walls.
  • Can induce septic shock.
  • Mediate attachment of bacteria to mucosal cells.
• Cytoplasmic Membrane
  • Present in both Gram-positive and Gram-negative bacteria.
  • Acts as a semipermeable membrane, controlling the flow of molecules.
• Cytoplasm
  • A colloidal system containing various solutes, including water, salts, and proteins.
  • Rich in ribosomes, DNA, and fluid.
• Mesosomes
  • Invaginations of the plasma membrane.
  • Increase membrane surface area for enzyme activity and transport.
  • May participate in cell replication.
• Periplasmic Space
  • The space between the cell membrane and cell wall.
  • Contains enzymes and proteins, including chemoreceptors.
• Ribosomes
  • Centers of protein synthesis.
  • Slightly smaller than eukaryotic ribosomes.
• Nucleus
  • Area where DNA is located.
  • Prokaryotic DNA is a single, circular molecule.
  • No nuclear membrane, nucleolus, mitotic spindle, or histones.
• Granules
  • Storage areas for nutrients.
• Capsule
  • Gelatinous layer covering the entire bacterium.
  • Composed of polysaccharide.
  • Plays a role in:
    • Virulence (limits phagocytosis).
    • Specific identification.
    • Vaccine development.
    • Adherence to human tissues.
• Pili (Fimbriae)
  • Hair-like filaments extending from the cell surface.
  • Shorter and straighter than flagella.
  • Composed of pilin protein.
  • Used for:
    • Attachment to target cells or surfaces.
    • DNA transfer during conjugation.
• Flagella
  • Long, whip-like appendages for movement.
  • Composed of flagellin protein.
  • Enable chemotaxis (movement towards nutrients).
• Spores
  • Highly resistant structures formed in response to adverse conditions.
  • Extremely resistant to heat and chemicals.