Microbiology Study Notes 2

Intro to Microbiology

  • Microbiology is the study of microbes, which are tiny organisms too small to see with the naked eye.
  • Microbes include:
    • Bacteria
    • Viruses
    • Fungi
    • Algae
    • Protozoa
  • Microbiology is important for understanding:
    • Diseases
    • Treatments
    • Vaccines
  • Microbes also play crucial roles in:
    • Recycling nutrients
    • Producing oxygen
    • Food production (e.g., bread and yogurt)
    • Cleaning pollution (e.g., oil spills)

Classification & Taxonomy

  • Taxonomy: The science of naming and organizing living things.
    • It shows how organisms are related.
  • Living things are grouped into 8 taxa:
    • Domain
    • Kingdom
    • Phylum
    • Class
    • Order
    • Family
    • Genus
    • Species
  • Mnemonic: "Divine King Phillip Came Over For Great Spaghetti."
  • Binomial Nomenclature:
    • Created by Carl Linnaeus.
    • Two-part naming system using genus and species (e.g., Homo sapiens).
    • Genus is capitalized, species is lowercase; both are italicized or underlined.

Bacteria Basics

  • Bacteria are living, single-celled, prokaryotic organisms.
  • Two domains of bacteria:
    • Eubacteria
    • Archaebacteria
  • Metabolism:
    • Autotrophs: Make their own food.
    • Heterotrophs: Must consume food.
  • Impact:
    • Some bacteria are helpful; others are harmful.
  • Types of Bacteria:
    • Gram-positive: Thick walls, stain purple.
    • Cyanobacteria: Perform photosynthesis, produce oxygen.
    • Chlamydias: Live inside other cells, cause disease.
    • Spirochetes: Spiral-shaped, digest food or cause illness.
    • Proteobacteria: Aid in digestion in the gut or cause ulcers.

Bacteria Shapes and Structures

  • Shapes:
    • Coccus: Spherical (spheres).
    • Bacillus: Rod-shaped (rods).
    • Spirillum: Spiral-shaped (spirals).
  • Arrangements:
    • May form chains or clusters.

Bacteria vs Animal Cells

  • Bacteria:
    • Simple.
    • No nucleus (prokaryotic).
  • Animal Cells:
    • Complex.
    • Have a nucleus (eukaryotic).

How Bacteria Reproduce

  • Binary Fission (asexual):
    • A single bacterium splits into two identical cells.
  • Conjugation (sexual):
    • Bacteria exchange plasmids (small loops of DNA).
    • Plasmids often carry genes like antibiotic resistance, making infections harder to treat.

Lab: Growing Bacteria

  • Scientists use agar in petri dishes.
  • Sterilization is crucial to avoid contamination.
  • Streak plate method: Used to introduce bacteria onto the agar.
  • Incubation: Typically at 37°C.
  • Colony Formation: Visible colonies form after 1-2 days.

What is a Virus?

  • Viruses are non-living particles composed of DNA or RNA enclosed in a protein coat (capsid).
  • Viruses cannot reproduce or function without entering a host cell.

Viruses vs Bacteria

  • Viruses: Non-living, require a host to reproduce.
  • Bacteria: Living, capable of reproducing independently.

Virus Reproduction: Two Cycles

  • Lytic Cycle:
    1. Virus attaches to host cell.
    2. Virus injects its DNA/RNA into the host cell.
    3. The viral DNA/RNA is replicated, creating new viral components.
    4. New viruses are assembled.
    5. The host cell bursts (lyses), releasing the new viruses.
  • Lysogenic Cycle:
    1. Viral DNA integrates into the host cell's DNA.
    2. The viral DNA remains dormant, replicating along with the host DNA.
    3. Under stress, the viral DNA can excise and enter the lytic cycle.

What is a Vaccination?

  • A vaccine is a weakened or dead version of a virus used to train the body's immune system.

How Vaccines Work

  • The vaccine triggers the immune system to produce antibodies.
  • Antibodies