Chapter 1 - Intro to Microbiology

Microorganisms

organisms too small to be seen with the unaided eye

Harmful Microbes

Pathogenic (disease-producing)

Helpful Microbes

• Food Production

• Chemical production

• Biochemical production

• Decompose organic waste

• Oxygen production

Microbiome 

group of microbes that live stably on/in the human body 

• help to maintain good health 

• prevent growth of pathogenic microbes 

• train the immune system to discriminate threats

Normal microbiota

collection of acquired microorganisms on or in a healthy human being

Disproving Spontaneous Generation

Pasteur disproved spontaneous generation by showing that microorganisms come from other microorganisms, not from nonliving matter.

• He boiled broth in an S-shaped flask to kill existing microbes.

• The curved neck allowed air in but trapped dust and microbes.

• No microorganisms grew in the broth unless the flask was tilted, showing contamination came from outside.
  This experiment proved life does not spontaneously arise and led to aseptic techniques.

Classification of Microorganism

• Bacteria

• Archaea

• Eukarya

  • Protists

  • Fungi

  • Plants

  • Animals

Bacteria

• Domain: Bacteria

• Cell type: Prokaryote

• Cellularity: Unicellular

• Extra facts: Cell walls contain peptidoglycan. Some are helpful (gut microbiota, nitrogen fixers), others cause disease (TB, strep).

Archaea

• Domain: Archaea

• Cell type: Prokaryote

• Cellularity: Unicellular

• Extra facts: Cell walls lack peptidoglycan. Often live in extreme environments (high salt, heat, methane). Not known to cause human disease.

Fungi

• Domain: Eukarya

• Cell type: Eukaryote

• Cellularity: Both (yeasts = unicellular, molds/mushrooms = multicellular)

• Extra facts: Cell walls made of chitin. Important decomposers. Some cause infections (Candida, ringworm).

Protozoa

• Domain: Eukarya

• Cell type: Eukaryote

• Cellularity: Unicellular

• Extra facts: Often motile using pseudopodia, cilia, or flagella. Can be parasitic (malaria, Giardia).

Algae

• Domain: Eukarya

• Cell type: Eukaryote

• Cellularity: Both (unicellular diatoms, multicellular seaweeds)

• Extra facts: Perform photosynthesis; produce much of Earth’s oxygen. Some make toxins (red tide).

Viruses

• Domain: None (acellular)

• Cell type: Neither prokaryote nor eukaryote

• Cellularity: Neither (acellular; protein coat + nucleic acid)

• Extra facts: Obligate intracellular parasites. Range from simple (RNA viruses) to complex (bacteriophages).

Multicellular Animal Parasites

• Domain: Eukarya

• Cell type: Eukaryote

• Cellularity: Multicellular (but eggs/larvae microscopic)

• Extra facts: Include flatworms (tapeworms) and roundworms. Cause diseases like schistosomiasis and ascariasis.