General Microbiology Overview

General Microbiology

• Microbiology is the study of all living organisms too small to see with the naked eye.
• Major fields include:
  • Bacteriology: Study of bacteria
  • Parasitology: Study of parasites
  • Mycology: Study of fungi
  • Virology: Study of viruses
  • Immunology: Study of the human immune response to infections.

Scale of the Invisible World

• There are 1000 millimeters in a meter.
• There are 1000 microns in a millimeter.
• An E. coli bacterium is about 1 micron long.
• A baker's yeast cell is about 10-15 microns in diameter.

History of Infectious Diseases

• Includes a timeline of major infectious diseases, types, pre-human hosts, and approximate death tolls.
  • E.g., Antonine Plague (165-180 AD) - believed to be either smallpox or measles; ~5 million deaths.

Key Figures in Microbiology

• Robert Hooke (1635-1703) made one of the first microscopes and observed plant cells.
• Antony van Leeuwenhoek (1632-1723) improved the microscope and observed microorganisms.
• Ilya Metchnikoff (1845-1916) was a pioneer in the study of the immune system.
• Paul Ehrlich (1854-1915) searched for "magic bullets" against diseases (e.g., syphilis).
• Gerhardt Domagk (1895-1964) developed the first sulfa drug.
• Sir Alexander Fleming (1881-1955) and Selman Waksman (1888-1973) discovered important antibiotics (penicillin, streptomycin).
• Louis Pasteur (1822-1895) demonstrated that life does not spontaneously generate.
• Robert Koch (1843-1910) developed Koch's postulates to establish links between specific microorganisms and diseases.

Prokaryotic and Eukaryotic Cells

• Two basic types of cells.
• Prokaryotic cells do not have a nucleus; bacteria are prokaryotic.
• Eukaryotic cells have a nucleus; fungi and parasites are eukaryotic.

Structure of Bacteria

• Cell wall: Nearly all bacteria have a rigid cell wall, containing peptidoglycan.
  • Gram-positive: Thick peptidoglycan layer.
  • Gram-negative: Thin peptidoglycan layer, outer membrane.
• Plasma membrane: Phospholipid bilayer, permeability barrier, transport.
• Internal structures: DNA, ribosomes, inclusions (storage bodies), etc.
  • Examples: plasmids, gas vacuoles, endospores.
• Flagella, pili, fimbriae: For motility, attachment, and conjugation.

Bacterial Growth

• Generation time: The time required for a bacterium to divide.
• Phases: Lag, log, stationary, death.

Bacterial Morphology

• Different shapes/structures:
  • Cocci (spherical)
  • Bacilli (rod-shaped)
  • Spirilla (spiral-shaped)
  • Others (e.g., vibrios).

This quiz covers the essential topics in microbiology, including the study of bacteria, fungi, viruses, and parasites. You will explore the scale of microorganisms and learn about key historical figures and infectious diseases that have shaped our understanding of microbiology. Test your knowledge on these fascinating microscopic life forms.