microbio intro + history 🦠

summer 2026, may-june

what are prokaryotes?

organisms that lack a membrane-bound nucleus and have a single circular chromosome. includes bacteria and archaea.

what are eukaryotes?

organisms with a membrane-bound nucleus and membrane-bound organelles. includes plants, animals, fungi, and protists.

define biogenesis.

the hypothesis that living matter arises only from pre-existing living matter (life from life).

what is spontaneous generation?

the REJECTED theory that living bacteria arise spontaneously from non-living matter (life from nothing).

what is pasteurization?

heating liquids to kill most pathogenic bacteria and prevent spoilage. does NOT kill all microorganisms.

define selective toxicity.

the ability to kill or inhibit the growth of pathogenic organisms while leaving the host unharmed.

who was Robert Hooke and what did he do?

(1665) first to see and describe "cells," leading to the cell theory.

who was Antoni van Leeuwenhoek?

(1684) first to view live microbes using a microscope; called them "animalcules”

what did Louis Pasteur discover/invent?

rejected spontaneous generation using swan neck flasks, discovered fermentation (yeast converts sugar to alcohol), developed pasteurization, demonstrated aseptic technique.

what are Koch's Postulates used for?

(4 steps) to prove a specific microbe causes a specific disease.

Koch's Postulates - procedure

1. the microbe must be present in every case of the disease and isolated from the host.

2. grow the isolated microbe in a pure culture (no contaminants).

3. inject the pure culture into a healthy lab animal; it must develop the same disease.

4. recover and grow the same microbe again in pure culture from the lab animal.

who was Edward Jenner?

(1798) developed the first vaccine (smallpox) by observing that cowpox infection provided immunity.

who was Paul Ehrlich?

(1908) dveloped the concept of selective toxicity and discovered Salvarsan to treat syphilis.

who was Alexander Fleming?

(1929) accidentally discovered the first antibiotic, Penicillin, from the mold Penicillium chrysogenum.

what is binomial nomenclature?

a two-part naming system: Genus (capitalized/underlined) + species (lowercase). Both italicized or underlined. Example: Staphylococcus aureus or S. aureus.

what is nitrogen fixation?

when microbes convert atmospheric nitrogen into a form plants can use.

what is a strain in microbiology?

a specific subtype of a species. Example: E. coli O157:H7 is a strain of E. coli.

more:

- the "O" stands for the antigen on the bacteria's outer cell wall (and 157 means it's the 157th type they categorized).

- the "H" stands for the antigen on its flagella, which is the little tail it uses to swim around (and 7 is the 7th type of tail).