Microbiology: Stains, Biofilm, and Cell Theory

Simple Stain

A staining technique that uses a single dye to color all cells the same color, providing information about morphology and arrangement.

Differential Stains

Stains that use two or more dyes to differentiate microbes based on properties, including Gram stain and acid-fast stain.

Gram Positive

Stains purple due to a thick peptidoglycan layer in the bacterial cell wall.

Gram Negative

Stains reddish-pink due to a thin peptidoglycan layer and the presence of an outer membrane.

Acid-Fast Stain

A differential stain that distinguishes acid-fast bacteria; results in red for acid-fast positive and blue for acid-fast negative.

Special Stains

Stains used to detect specific microbial structures such as capsules, endospores, and flagella.

Capsules

A gelatinous layer surrounding some bacterial cells that provides protection against antibiotics.

Endospores

Dormant, resistant structures formed by some bacteria, particularly Bacilli, that allow survival in harsh conditions.

Flagella

Whip-like appendages that enable motility in bacteria.

Binomial Nomenclature

The correct format for naming species, with the genus name capitalized and the species name in lowercase, both italicized.

Biofilms

Complex communities of diverse microbes that adhere to surfaces and secrete a protective gelatinous matrix.

Spontaneous Generation

The discredited hypothesis that living organisms arise from nonliving matter.

Cell Theory

A fundamental concept in biology stating that all living organisms are composed of cells and all cells arise from pre-existing cells.

Endosymbiotic Theory

The theory that eukaryotic cells evolved from prokaryotic cells through a symbiotic relationship.

Germ Theory

The theory that diseases are caused by microscopic organisms, rather than by bad air or other mystical causes.

Koch's Postulates

A series of criteria to establish the causative relationship between a specific microbe and a specific disease.

Robert Hooke

The scientist who first described cells while observing dead plant tissue.

Johann Needham

A scientist whose experiments with broth supported spontaneous generation, later contradicted by Lazzaro Spallanzani.

Ignatz Semmelweis

A physician who demonstrated the importance of handwashing in preventing infections.

Louis Pasteur

A microbiologist who contributed to germ theory and developed pasteurization to eliminate harmful microorganisms.

Joseph Lister

A surgeon known for advocating antiseptic techniques in surgery to prevent infections.

Francesco Redi's Experiment

An experiment challenging spontaneous generation by showing that maggots come from flies, not from meat.

Lazzaro Spallanzani

A scientist who improved Needham's broth experiment and found no microbial growth, disputing spontaneous generation.