Microbiology Fundamentals: Tools of the Laboratory

Flashcards based on Microbiology Fundamentals Lecture Notes to help students review key concepts for their upcoming exams.

What are the Five I's of Microbiology?

Inoculation, Incubation, Isolation, Inspection, and Identification

What is the definition of 'Medium' in microbiology?

Nutrients for the growth of microbes

What is an 'Inoculum'?

A small sample of microbes

What is 'Inoculation'?

The introduction of an inoculum into media to culture microbes

What is an incubator?

A temperature-controlled chamber to encourage the multiplication of microbes

What are the three physical states of media?

Liquid, Semisolid, and Solid

What is Agar?

Complex polysaccharide isolated from Gelidium, solid at room temperature, liquefies at 100°C, solidifies at 42°C, flexible and moldable, not a digestible nutrient for most microorganisms

What is defined or synthetic media?

Composition is precisely chemically defined

What is complex media?

One or more components is not chemically defined; contains extracts of animals, plants, or yeasts

What is general-purpose media?

Grow as broad a spectrum of microbes as possible; generally complex

What is enriched media?

Contains complex organic substances such as blood, serum, hemoglobin, or special growth factors for the growth of fastidious microbes

What is selective media?

Contains one or more agents that inhibit the growth of a certain microbe or microbes

What is differential media?

Allow multiple types of organisms to grow but display visible differences in how they grow

What is reducing medium?

Contains a substance that absorbs oxygen or slows the penetration of oxygen; important for growing anaerobic bacteria

What is transport media?

Used to maintain and preserve specimens that have to be held for a period of time before clinical analysis

What is carbohydrate fermentation media?

Contains sugars that can be fermented with a pH indicator to show this reaction

What is a colony?

A macroscopic cluster of cells appearing on a solid medium arising from the multiplication of a single cell

How can microbes be identified?

Microscopic appearance, characterization of cellular metabolism, determination of nutrient requirements, products given off during growth, presence of enzymes, and mechanisms for deriving energy, genetic and immunologic characteristics

What are the dimensions of macroscopic organisms given in?

Centimeters (cm) and meters (m)

What are the dimensions of microscopic organisms range from?

Millimeters (mm), to micrometers (μm), to nanometers (nm)

What is Bright-Field Microscopy?

The most widely used type of light microscope

What is Dark-Field Microscopy?

Brightly illuminated specimens surrounded by a dark (black) field

What is Phase-Contrast Microscopy?

Transform subtle changes in light waves passing through the specimen into differences in light intensity

What is Fluorescence Microscopy?

Uses dyes (acridine, fluorescein) and minerals that show fluorescence, emitting visible light when bombarded by short ultraviolet rays

What is Confocal Microscopy?

Uses a laser beam of light to scan various depths in the specimen

What is Transmission Electron Microscope (TEM)?

The method of choice for viewing the detailed structure of cells and viruses

What is Scanning Electron Microscope (SEM)?

To create an extremely detailed three-dimensional view of all kinds of objects

What are Fresh, Living Preparations?

Cells are suspended in water, broth, or saline to maintain viability and provide a medium for locomotion

What is a wet mount?

Consists of a drop or two of culture placed on a slide and overlaid with a cover slip

What is a hanging drop?

A drop of culture is placed in a concave (depression) slide, Vaseline adhesive or sealant, and cover slip are used to suspend the sample

What is staining?

Procedure that applies colored chemicals (dyes) to specimens

What is a positive stain?

Dye sticks to the specimen and gives it color

What is a negative stain?

Does not stick to the specimen but settles some distance from its outer boundary, forming a silhouette

What are Simple Stains?

Only require a single dye and an uncomplicated procedure

What are Differential Stains?

Use two differently colored dyes: the primary dye and the counterstain

What are the sequential applications of the Gram Stain?

Crystal violet (the primary stain), Gram’s iodine (the mordant), An alcohol rinse (decolorizer), Safranin (the counterstain)

What does the acid-fast stain do?

Differentiates acid-fast bacteria (pink) from non-acid-fast bacteria (blue)

What does the endospore stain do?

Stain distinguishes between endospores and vegetative cells