Bacterial Classification, Staining, and Morphology

Vocabulary practice flashcards covering microscopy magnification calculations, Gram staining principles and steps, taxonomic concepts, identification methods, prokaryotic morphologies, reproduction, and environmental adaptations.

Total Magnification Formula

$$\text{Total Magnification} = (\text{Objective Lens Magnification}) \times (\text{Ocular Lens Magnification})$$

Gram Staining

A staining method that classifies bacteria as either Gram-positive or Gram-negative, reflecting differences in their cell wall structure and guiding treatment.

Crystal violet

The primary stain used in the first step of the Gram staining procedure.

Iodine (Gram Staining)

The mordant applied as the second step of the Gram staining procedure.

Alcohol or acetone (Gram Staining)

The decolorizer used as the third step in the Gram staining procedure.

Safranin

The counterstain used as the fourth step in the Gram staining procedure, which stains decolorized Gram-negative cells red.

Gram-positive bacteria

Bacteria that appear purple after completing the Gram stain because their thick peptidoglycan cell wall retains the crystal violet stain.

Gram-negative bacteria

Bacteria that lose the crystal violet-iodine complex during decolorization due to their thin peptidoglycan layer and outer membrane, taking up the red safranin counterstain instead.

Carl Linnaeus

The scientist who developed the binomial nomenclature system.

Three Classification Domains

The three domains proposed by Carl Woese: Bacteria, Archaea, and Eukarya.

Classification

Grouping organisms by shared characteristics.

Nomenclature

Assigning names to organisms.

Identification

Determining the identity of an organism.

Phage typing

A bacterial identification method that uses bacteriophages (viruses that infect bacteria) to determine which phages a bacterial strain is susceptible to.

Serological tests

Tests that use antibodies to detect specific antigens on bacteria; binding of the antibody identifies the bacteria.

Dichotomous key

A step-by-step tool that uses paired choices to identify organisms.

Biochemical tests

Tests used to identify bacteria, with examples including the Catalase test and the Oxidase test.

Prokaryotic morphologies

The eight shapes of prokaryotes: Coccus, Bacillus, Coccobacillus, Vibrio, Spirillum, Spirochete, Pleomorphic, and Filamentous.

Endospore

A tough, dormant structure for survival produced by bacterial genera such as Bacillus and Clostridium.

Binary fission

The most common type of prokaryote cell reproduction.

Viviparity

Giving birth to live offspring, rather than laying eggs or spores.

Extremophile

An organism that lives in extreme environments.

Halophile

An organism that loves and thrives in very salty environments.

Thermophile

An organism that thrives at high temperatures.

Hyperthermophile

An organism that thrives at extremely high temperatures, often above $80^\circ\text{C}$.