CAGS Microbiology Lab Midterm Study Guide

Vocabulary flashcards derived from the CAGS Microbiology Lab Midterm Study Guide covering lab terminology, thermal classifications, tests, and media characteristics.

Defined Media

Media in which the exact biochemical components of the entire medium are known.

Complex Media

Media containing complex material of biological origin where the exact biochemical components are unknown (e.g., beef extract, blood agar).

Selective Media

Media that selects for the growth of a desired organism while stopping the growth or killing non-desired organisms.

Differential Media

Media that differentiates closely related organisms or groups of organisms based on biochemical properties, displaying a visible change when growth of the target organism is present.

Environmental Streak Method

The specific streak method used when collecting an environmental sample.

Colony Morphology Terms

Classifications used to identify colony growth patterns on an inoculated plate, including round, irregular, filamentous, and rhizoid.

Good Quadrant Streak Plate

A streak plate where bacterial density decreases with each quadrant, resulting in isolated colonies in the final quadrant.

Psychrophiles

Organisms with an ideal temperature growth range below $20^\text{C}$.

Psychrotrophs

Organisms with an ideal temperature growth range from $0^\text{C}$ to $30^\text{C}$.

Mesophiles

Organisms with an ideal temperature growth range from $15^\text{C}$ to $45^\text{C}$, encompassing most human microbiome bacteria and human pathogens.

Thermophiles

Organisms with an ideal temperature growth range above $40^\text{C}$.

Extremophiles

Organisms with an ideal temperature growth range above $65^\text{C}$.

GasPak System Reaction

A process where sodium bicarbonate in the packet reacts with water in the air to produce hydrogen and carbon dioxide gases to generate an anaerobic environment.

Superoxide Dismutase

An enzyme that catalyzes the conversion of superoxide radicals to hydrogen peroxide.

Catalase

An enzyme that converts hydrogen peroxide into water and oxygen gas.

Flavoprotein

A carrier molecule in the ETC that can bypass the next carrier in the chain and transfer electrons directly to oxygen, generating cellular toxins hydrogen peroxide ($\text{H}_2\text{O}_2$) and superoxide radical ($\text{O}_2^-$).

Catalase-Positive Result

The formation of oxygen bubbles when hydrogen peroxide is added to the organism.

Cytochrome c Oxidase

The specific respiratory enzyme tested for in the oxidase test.

Oxidase Test Positive Result

A dark blue color change occurring within $20\text{ seconds}$.

Tetramethyl-p-phenylenediamine

A chromogenic reducing agent in the oxidase test that develops a blue color when oxidized.

MacConkey Agar

A selective and differential medium that inhibits Gram-positive bacteria using crystal violet and bile salts, while differentiating Gram-negative organisms based on lactose utilization using phenol red.

Probable Coliform (MacConkey Agar)

An organism that ferments lactose to produce acid, resulting in pink-to-red growth with or without bile precipitate.

Noncoliform (MacConkey Agar)

An organism that does not ferment lactose, producing colorless growth on MacConkey agar.

Phenol Red Test

A differential test using phenol red indicator (turns yellow below pH $6.8$ due to acid production) to distinguish sugar-fermenting enteric bacteria from other Gram-negative bacilli.

Motility Test Agar Concentration

Agar concentration reduced to $0.4\text{\%}$ to create a semisolid medium.

Tetrazolium Salt (TTC)

An indicator in motility agar that turns red and insoluble when reduced by gaining an electron from bacterial metabolic activity.