Microbiology Exam 1: Chapters 1, 3 & 8

Microorganisms and Historical Perspectives

• Microorganisms are organisms too small for the naked eye to see.
• Early civilizations recognized the connection between sewage and disease by constructing aqueducts to manage waste.

Notable Historical Figures in Medicine

• Hippocrates: Known as the "Father of Western Medicine," he attributed diseases to natural causes rather than supernatural ones.
• Thucydides: Regarded as the "Father of Scientific History," he promoted evidence-based analysis of cause and effect relationships in diseases.
• Marcus Terentius Varro: Suggested that unseen entities called microorganisms could cause diseases.

Development of Microscopy

• Zacharias Janssen: Created the first simple microscope.
• Robert Hooke: Enhanced microscope design with better light and specimen holding adjustments.
• Antony van Leeuwenhoek: Dubbed the "Father of Microbiology," he developed advanced lenses to observe microbes and documented findings of muscle fibers, sperm, and blood flow.

The Golden Age of Microbiology

• Louis Pasteur: Established the germ theory, disproved spontaneous generation, and developed vaccines for rabies.
• Robert Koch: Identified specific pathogens responsible for diseases like cholera and anthrax.
• The attenuation principle significantly reduced pathogen dangers in vaccines.

Taxonomy and Classification

• Taxonomy: The scientific classification of living organisms.
• Carolus Linnaeus: Developed the binomial nomenclature system for naming species.
• Ernst Haeckel: Introduced a fourth taxonomic kingdom, Protista and Monera.
• Robert Whitaker: Proposed a five-kingdom system, adding fungi and defining superkingdoms.
• Carl Woese: Identified three domains of life: Bacteria, Archaea, and Eukarya.
• Current kingdoms include Animalia, Plantae, Fungi, Protista, Archaea, and Bacteria.

Understanding Microbial Sizes and Structures

• Limitation of the human eye: Can see objects down to 1mm or 100 micrometers.
• Average sizes: Animal cells (10 micrometers), Bacterial cells (1 micrometer), Viruses (0.1 micrometer).
• Bacterial cells consist of a cell wall, plasma membrane, cytoplasm, ribosomes, and DNA.
• Common bacterial shapes: Bacilli (rod-shaped), Cocci (spherical), Spirillum, Spirochete, and Vibrio (spiral shapes).
• Archaea: Capable of thriving in extreme environments, including hot and cold extremes.

Characteristics and Applications of Microorganisms

• Algae are utilized in biofuels, food, pharmaceuticals, and oxygen production in aquatic systems.
• Protozoa classification relies on movement mechanisms like cilia, flagella, and pseudopods.
• Fungi can be unicellular (yeast) or multicellular (molds), serve as decomposers, and typically grow in warm, moist environments.
• Yeasts are unicellular, used in food production, and can cause diseases. Molds are multicellular, used in pharmaceuticals, and can trigger allergies.
• Helminths: Parasitic worms with microscopic eggs and larvae that cause disease.

Viruses and Their Classification

• Viruses consist of DNA or RNA and are not considered alive due to lack of reproduction and metabolism.
• Subfields of microbiology include bacteriology, mycology, protozoology, parasitology, virology, and immunology.

Abiogenesis and Cell Theory

• Abiogenesis: The theory that life could arise from non-living matter.
• Francisco Redi: Disproved this theory by demonstrating that decaying meat did not spontaneously generate life.
• Louis Pasteur: Further disproved abiogenesis by showing no microbial growth in sterilized broth exposed to air unless contaminated.

Germ Theory and Epidemiology

• Cell Theory: States that all cells arise from pre-existing cells.
• Germ Theory: Suggests that diseases may be caused by microbial infections.
• Ignaz Semmelweis: Advocated handwashing with lime solutions to lower childbirth mortality rates.
• John Snow: Mapped cholera cases and traced outbreaks to a contaminated water source.
• Joseph Lister: Used carbolic acid to reduce postoperative infection deaths.
• Florence Nightingale: Utilized statistics to highlight preventable deaths due to poor hygiene.

Koch’s Postulates

• Four postulates for linking specific microbes to diseases:
  • Microbe must be present in every case of the disease.
  • Microbe must be isolated and cultured away from the host.
  • Microbe must cause disease in a healthy host when introduced.
  • Microbe must be re-isolated from the experimental host.

Exceptions and Modern Focus of Germ Theory

• Exceptions to Koch’s postulates include difficulties in isolating some microbes and pathogens causing multiple diseases.
• Modern germ theory research focuses on antibiotic resistance, emerging diseases, and mechanisms of microbial infections.