Microbiology Laboratory Equipment and Materials

A comprehensive set of study flashcards covering key laboratory equipment, principles, and procedures in microbiology.

What range of mass measurement is an analytical balance commonly used for?

Sub-milligram range.

How does an electric analytical balance determine the mass of a substance?

It uses an electromagnet to create a force that counteracts the mass of the substance rather than measuring the mass directly.

What three factors are combined in an autoclave to achieve sterilization and disinfection?

Time, pressure, and steam.

What is the primary sterilization agent used in an autoclave?

Steam.

How is the air intake adjusted on a Bunsen burner?

Openings on the sides of the metal tube can be adjusted with a collar to control the amount of air entering.

What is a common microbiology laboratory application for the Bunsen burner?

Micro-loop sterilization.

On what physical principle does a laboratory centrifuge operate to separate mixture components?

Sedimentation, where high-speed rotation causes denser particles to move away from the center while lighter particles remain near the center.

Why are sample tubes aligned at an angle in a laboratory tabletop centrifuge?

To allow particles to travel a shorter distance before hitting the bottom.

What parameter does a colony counter estimate when scanning culture plates?

The number of CFU (colony forming units) to estimate the density or concentration of microorganisms in liquid culture.

What is the underlying working principle of deep freezers for long-term culture preservation?

Under extremely low temperatures, there is minimum microbial growth, allowing preservation without changing the concentration of microorganisms.

How does a homogenizer break down large globules in a coarse emulsion into smaller particles?

By passing them under high pressure through a narrow orifice formed by a metal rod with parallel comb-like openings.

Why are hot plates often preferred over water baths for heating glassware in a laboratory?

Water baths can be hazardous in the event of spills or overheating.

What is the primary operational difference between a forced air hot air oven and a static air hot air oven?

A forced air hot air oven uses a fan to distribute heated air evenly throughout the oven, whereas a static air hot air oven uses heating coils at the bottom with no fan.

What special function does a shaking incubator provide compared to a standard incubator?

It provides continuous movement of the culture required for cell aeration and solubility studies.

How long before use must a Laminar Air Flow cabinet be turned on?

15 minutes before use to ensure complete sterilization.

Which components inside a Laminar Hood maintain a sterile workstation environment?

A High-Efficiency Particulate Air (HEPA) filter and a shortwave ultraviolet germicidal lamp.

Why is a magnetic stirrer preferred over other mechanical stirrers in microbiology labs?

It is noise-free and uses a tiny stir bar that reduces the risk of contamination.

What are the primary labeled components of the compound light microscope?

Eyepiece, Camera port, Coarse focus knob, Fine focus knob, Objective lens, Slide area, Stage, Condenser, and Light source.

Why is a digital pH meter referred to as a potentiometric pH meter?

Because it measures the difference in electric potential between a reference electrode and a pH electrode.

Which physical law governs quantitative analysis in spectrophotometry, and what does it state?

Beer-Lambert Law, which states that the absorbance of light by a solution of a particular wavelength is directly proportional to the concentration of the substance.

How does a vortex mixer agitate liquid samples inside sample tubes?

Motorized draft shafts oscillate and transfer movement to the sample tubes, causing sample fluids to undergo turbulent flow.

What safety advantage does a water bath offer when heating chemical reagents?

It provides controlled, uniform heating suitable for flammable chemicals that could ignite under direct flame.

What basic physical processes are utilized by a water distiller to purify water?

Water is brought to a boil and then condensed back into liquid form.

In gel electrophoresis, in which direction do sample components migrate relative to the electrodes?

They move away from the negative ($\Theta$) electrode toward the positive ($\oplus$) electrode.

What are the four step-by-step procedures involved in Gram staining?

1. Prepare smear and stain with Crystal violet. 2. Apply Gram's Iodine as mordant. 3. Wash with 95% ethanol or acetone decolorizer. 4. Counterstain with Safranin.

Which side of paper should face the petri dish when wrapping it, and why?

The clean side should face the petri dish, because if paper with print gets wet, the ink will transfer to the dish and obscure microbial observation.

Why are cotton plugs utilized when culturing aerobic microorganisms in test tubes?

Cotton plugs allow gas exchange while preventing outside microorganisms from contaminating the culture.