Exam 1 Review Medium

Introduction to Microorganisms

• Microorganisms are organisms too small to be seen with the naked eye.

Early Civilization and Disease

• Aqueducts were designed to transport waste, demonstrating an early understanding of sanitation.
• Hippocrates proposed natural causes for diseases, diverging from supernatural explanations.
• Thucydides advocated for evidence-based analysis in understanding disease causes.
• Varro suggested that unseen entities (microorganisms) could be disease agents.

Contributions to Microscopy

• Zacharias Janssen invented the first simple microscope.
• Robert Hooke enhanced microscopes with fine adjustments and lighting.
• Antony van Leeuwenhoek developed advanced lenses to observe microbes, earning him the title "Father of Microbiology."

The Golden Age of Microbiology

• Louis Pasteur significantly advanced germ theory, disproved spontaneous generation, and created vaccines for rabies.
• Robert Koch identified specific pathogens responsible for diseases like cholera and anthrax.
• The attenuation principle reduced the pathogenicity of microbes, aiding in vaccine development.

Taxonomy and Classification

• Taxonomy is the classification of living organisms.
• Carolus Linnaeus coined the binomial nomenclature for species classification.
• Ernst Haeckel proposed a fourth kingdom, including protista and monera.
• Robert Whitaker introduced a five-kingdom system, adding fungi.
• Carl Woese classified life into three domains: Bacteria, Archaea, and Eukarya.
• Six current kingdoms include Animalia, Plantae, Fungi, Protista, Archaea, and Bacteria.
• The eight taxonomic ranks are Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
• Organism names in binomial nomenclature are italicized, with only the genus capitalized.

Measurement in Microbiology

• Limitations of the human eye: cannot see objects smaller than 1 mm (100 micrometers).
• Average sizes: Animal cells (~10 micrometers), bacterial cells (~1 micrometer), viruses (~0.1 micrometer).
• Bacteria are composed of cell wall, plasma membrane, cytoplasm, ribosomes, and DNA.

Bacterial Characteristics

• Bacteria can exhibit various shapes: Bacilli (rod-shaped), Cocci (spherical), Spirilla (spiral), Vibrio (comma-shaped).
• Archaea can survive in extreme environments.
• Algae serve as biofuels, food products, pharmaceuticals, and produce oxygen in aquatic settings.
• Protozoa classification is based on movement mechanisms: cilia, flagella, and pseudopods.
• Fungi can be unicellular (yeasts) or multicellular (molds) and are essential decomposers.
• Helminths are multicellular parasitic worms with associated microscopic eggs and larvae.

Viruses

• Viruses consist of DNA or RNA and are not considered alive as they do not reproduce or perform metabolic functions.

Subfields of Microbiology

• Key areas include Bacteriology, Mycology, Protozoology, Parasitology, Virology, and Immunology.

Abiogenesis and Experimental Evidence

• Abiogenesis refers to the idea that life can arise from non-living matter.
• Francisco Redi disproved this by showing that decaying meat was contaminated by fly eggs.
• Louis Pasteur demonstrated microorganisms do not grow in sterile broth unless exposed to air.

Cell Theory and Germ Theory

• Cell Theory states that all cells arise from pre-existing cells.
• Robert Hooke discovered "cells" when observing cork.
• Germ Theory posits that diseases may originate from microbial infections.

Key Historical Figures

• Ignaz Semmelweis found that handwashing reduced childbirth mortality rates.
• John Snow traced a cholera outbreak in 1848 to a contaminated water pump.
• Joseph Lister introduced carbolic acid as an antiseptic to reduce post-operative infections.
• Florence Nightingale used statistics to highlight preventable causes of death through sanitation and hygiene.

Koch's Postulates

• Criteria for linking specific pathogens to diseases:
  • Microbes must be present in diseased organisms.
  • Microbes must be isolated and cultured.
  • Cultured microbes must cause disease in healthy hosts.
  • Microbes must be re-isolated from the experimentally infected hosts.
• Exceptions exist, such as microbes not being isolated in all cases and some pathogens causing multiple diseases.

Eukaryotes vs Prokaryotes

• Shared structures: Plasma membrane, cytoplasm, ribosomes, and DNA.
• Unique to prokaryotes: Circular DNA, bacterial flagella. Unique to eukaryotes: Linear DNA, organelles like mitochondria and chloroplasts.
• Cytoplasm includes all cellular contents; cytosol refers to just the fluid.

Bacterial Structure and Function

• Bacteria reproduce mainly via binary fission.
• Pleomorphic bacteria can vary in size and shape.
• Glycocalyx functions in nutrient trapping, attachment to surfaces, and evasion from immune cells.
• Flagella provide mobility and have various arrangements (monotrichous, amphitrichous, lophotrichous, peritrichous).
• The primary function of fimbriae is to enable attachment to surfaces, while pili facilitate genetic material transfer.

Cell Wall Composition

• Bacterial cell walls consist of peptidoglycan, made from N-acetylglucosamine (NAM) and N-acetylmuramic acid (NAM).
• Gram-positive cell walls feature a thick peptidoglycan layer with teichoic acids, whereas Gram-negative cell walls have a thin layer with an outer membrane containing lipopolysaccharides (LPS).

Endotoxins and Membrane Dynamics

• Lipid A in LPS acts as an endotoxin, provoking strong immune responses.
• Porins in Gram-negative bacteria regulate nutrient passage and can hinder antibiotic efficacy.
• Mycoplasma bacteria are unique in lacking a cell wall.

Fluid Mosaic Model of Cell Membrane

• Describes the cell membrane as a flexible structure composed of a phospholipid bilayer with proteins embedded.

Metabolism

• Metabolism encompasses all biochemical reactions, with energy stored in cells primarily as ATP.
• Catabolic reactions break down larger molecules, releasing energy, while anabolic reactions build larger molecules, requiring energy.

Enzymatic Function and Regulation

• Enzymes act as catalysts, speeding up reactions by binding substrates to their active sites.
• Cofactors are inorganic compounds aiding enzyme activity, while coenzymes are organic molecules derived from vitamins.
• Active sites bind substrates; allosteric sites modulate enzyme function.

These concise notes cover key aspects required for understanding microorganisms and their significance across various contexts.

Test your knowledge on the key figures and fundamental concepts in microbiology. This quiz covers important scientists like the 'Father of Microbiology', the development of germ theory, and significant contributions by pioneers such as Robert Koch. Challenge yourself and learn about essential microbiological principles and classification methods.