Microbiology Quiz

Microbiology

• Microbiology is the study of the microbial world.

Major Groups of Microorganisms

• Three groups of microorganisms: Prokaryotes, Eukaryotes, and Acellular Infectious Agents

Characteristics of Microorganisms

• Prokaryotes:

  • Cell type: Prokaryotic
  • Number of cells: Unicellular
  • Membrane-bound organelles: No
  • Ribosomal RNA sequences: Unique to the group
  • Peptidoglycan in cell wall: Yes (in bacteria)
  • Typical size range: 0.3–2 μm

• Archaea:

  • Cell type: Prokaryotic
  • Number of cells: Unicellular
  • Membrane-bound organelles: No
  • Ribosomal RNA sequences: Unique to the group
  • Peptidoglycan in cell wall: No
  • Typical size range: 0.3–2 μm

• Eukarya:

  • Cell type: Eukaryotic
  • Number of cells: Unicellular or Multicellular
  • Membrane-bound organelles: Yes
  • Ribosomal RNA sequences: Unique to the group
  • Peptidoglycan in cell wall: No
  • Typical size range: 5–50 μm

Scientific Names

• Developed by Carl Linnaeus (1700s)
• Latin style, reflects a characteristic or honors a scientist
• Structure:
  • 2-part naming system (Binomial system)
  • Part 1 = Genus (capitalize the first letter)
  • Part 2 = species (all lowercase)
• Formatting:
  • Online formats – use italics
  • Handwritten formats – underline
  • Abbreviate after first use to include only the first letter of the Genus

History of Microbiology

• Key figures and events in microbiology history

  • Robert Hooke (1665): Observed cells
  • Antonie van Leeuwenhoek (1674): Observed microorganisms

• Spontaneous generation vs. Biogenesis

  • Spontaneous generation: belief that life can arise from nonliving matter
  • Biogenesis: living matter arises only from pre-existing living matter
  • Louis Pasteur (1861): Disproved spontaneous generation

• Germ Theory of Disease

  • Microorganisms cause certain diseases
  • Joseph Lister (1860s): Used phenol to reduce surgical wound infections
  • Robert Koch (1876): Claimed that specific microbes cause definite diseases demonstrated with anthrax and Koch's postulates
  • Edward Jenner (1796): Developed a vaccine against smallpox
  • Paul Ehrlich (1909): Noticed dyes that stained bacteria differently, proposed the concept of selective toxicity developed salvarsam to treat syphilis
  • Alexander Fleming (1928): Discovered penicillin

Other interesting facts about microorganisms

• Microbes can make vitamins
• Microbes can make antibiotics
• Microbes can make chocolate
• Microbes can degrade explosives
• Microbes can make plastics
• Microbes can be used for biofinishing jeans
• Microbes convert atmospheric nitrogen
• Microbes degrade pollutants
• Microbes can make food, cement and insecticides
• Microbes are an essential component of a healthy human
• Microbes play important roles in research
• Microbes can be harmful (pathogens)

Microscopy

• Light microscope: Uses visible light to observe specimens

• Compound light microscope: Uses two lenses to magnify the image

• Objective lens: Lens closest to the specimen. Magnifies between 4x to 100x

• Ocular lens: The eyepiece. Magnifies by 10x

• Resolution: ability to distinguish fine detail and structure. The shortest the wavelength the better

• Electron microscope: Uses electrons instead of light. Resolution power is greater

• Transmission electron microscope (TEM): Used to see internal structures.

• Scanning electron microscope (SEM): Used to see surfaces.

• Atomic force microscope (AFM): Used to see molecules.

Microbiology stains

• Simple stains: use only one dye
• Differential stains: react differently with different bacteria (Gram stain). Gram positives retain the stain (purple), Gram negatives do not (pink)
• Acid-fast Stain: detects the presence of wax compounds in cell walls, typically used for Mycobacterium (e.g. tuberculosis)
• Capsule stain: detects a thick polysaccharide layer; bacteria with a capsule retain the dye and appear colorless.

Cell structure (prokaryotes)

• Prokaryotes (e.g., bacteria, archaea): DNA is not enclosed in a nucleus.

• Eukaryotes: (e.g., fungi, protozoa, algae, plants, animals): DNA is enclosed in a nucleus, contains specialized organelles.

• Bacteria:

  • Shape: Coccus, Bacillus, Vibrio, Spirillum, Spirochete
  • External structures: Capsules, slime layers, flagella, fimbriae, pili
  • Internal structures: Cytoplasm, nucleoid (contains DNA), ribosomes, storage granules, endospores

• Cell wall Structure and roles

  • Peptidoglycan (in bacteria): a complex macromolecule that forms a mesh-like structure, important for bacterial shape and preventing cell rupture, and used in differentiating bacteria via the Gram stain.
  • Gram-positive cell walls: Thick peptidoglycan layer, teichoic acids, cytoplasmic membrane
  • Gram-negative cell walls: Thin peptidoglycan layer, outer membrane, lipopolysaccharide (LPS), cytoplasmic membrane

• Cell Structure (Eukaryotes)*

• Cytoplasm: The substance inside the plasma membrane of eukaryotes.

• Cytoskeleton: made of protein filaments that give a cell shape, structure, and aids in the transport of substances.

• Ribosomes: Sites of protein synthesis, larger and heavier (80S) than prokaryotic ribosomes.

• Nucleoid: Contains the bacterial chromosome, which has all the genetic information for cell functions; may also have plasmids.

• Endospores: Special resting structures that allow some Gram-positive bacteria to enter a dormant state.

• Flagella, Cilia: Appendages that enable movement and transporting substances.

• Membrane-Bound Organelles: Nucleus, Mitochondria, Chloroplasts, Golgi Apparatus, Peroxisomes, Lysosomes

Test your knowledge on microbiology concepts including classification, naming systems, and bond types. This quiz covers key contributions from historical figures such as Carl Linnaeus and Robert Hooke, as well as fundamental chemistry principles relevant to microorganisms.