History of Microbiology & Prokaryotic Cells

Practice flashcards covering the history of microbiology, key scientists, bacterial structures, and prokaryotic cell components based on lecture notes.

Antonie van Leeuwenhoek

Known as the ‘Father of Microbiology’ (1632-1723), he developed the first lens capable of visualizing microbes and discovered single-cell microorganisms.

Animalcules

The term used by Antonie van Leeuwenhoek to describe the single-cell microorganisms he discovered.

Edward Jenner

Known for the first extensively documented vaccination (1749-1823), he demonstrated that exposure to cowpox provides immunity against smallpox.

Louis Pasteur

A scientist (1822-1895) who provided evidence for Germ Theory, refuted Spontaneous Generation using swan-neck bottle experiments, and developed pasteurization.

Robert Koch

The founder of medical bacteriology (1843-1910) who developed culture media for growing bacteria and established postulates to link specific microbes to specific diseases.

Koch’s Postulates

A four-step criteria used to identify the causative agent of a disease: the microbe must be found in all diseased but no healthy organisms, isolated and grown in pure culture, cause disease in a healthy host, and be reisolated as identical to the original agent.

Alexander Fleming

The scientist (1881-1955) who discovered penicillin, the first mass-produced antibiotic, and demonstrated its bactericidal effects against primarily gram-positive bacteria.

Penicillin Mechanism

Inhibits proper peptidoglycan cross-links, leading to bacterial cell wall dysfunction and eventual cell death.

Microscopic Relative Sizes

A typical virus measures about $100\,\text{nm}$, a typical bacterium is about $1\,\mu\text{m}$, and a typical plant or animal cell is between $10\text{--}100\,\mu\text{m}$.

Coccobacillus

A bacterial shape that is a combination of spherical (coccus) and rod-shaped (bacillus).

Nucleoid

A condensed area of chromosomal DNA found within prokaryotic cells that does not readily stain and appears lighter under a transmission electron microscope.

70S Ribosomes

Prokaryotic ribosomes composed of two subunits: the $30S$ (small subunit) and the $50S$ (large subunit).

Peptidoglycan

A polymer composed of alternating NAM and NAG subunits cross-linked by peptide bridges, providing tensile strength to the bacterial cell wall.

Gram-positive Cell Wall

A structurally simple cell wall containing a thick layer of peptidoglycan with embedded teichoic acid external to the plasma membrane.

Gram-negative Cell Wall

A complex cell wall containing a thin layer of peptidoglycan and an outer membrane that includes lipopolysaccharide (LPS).

Lipopolysaccharide (LPS)

A toxin found in the outer membrane of gram-negative bacteria composed of Lipid A, a core polysaccharide, and an O side chain.

Mycolic Acid

Waxy acids found in the cell walls of Mycobacteriaceae that are detected using the acid-fast staining protocol.

Capsules

An organized layer of polysaccharides (a type of glycocalyx) that surrounds some bacterial cells.

Fimbriae

Short, numerous protein appendages used by bacteria for surface attachment.

Pili

Longer, less numerous protein appendages that aid in surface attachment and DNA transfer.

Bacterial Flagellum

A protein appendage used for locomotion consisting of three basic parts: a basal body, a hook, and a filament.

Periplasmic Space

The area between the outer membrane and the cytoplasmic membrane in bacterial cells, comprising $20\%$ to $40\%$ of total cell volume and containing the peptidoglycan layer.

Plasmids

Separate, double-stranded DNA molecules that sit outside the main chromosome in the bacterial cell body.

Inclusion Bodies

Dense aggregates of nutrients, energy reserves, or misfolded proteins found within the bacterial cytoplasm.

Mesosome

A structure in the bacterial cell that assists with cell respiration, DNA replication, and the building of new cell walls during division.