Chapter 3

What is the definition of a micrometer (μm)?

A micrometer (μm) is equal to 10^-3 mm or 10^6 m, representing one millionth of a meter.

What is the size range for bacteria in micrometers?

Bacteria typically range from 0.1 to 5 μm.

What is the resolution limit of a compound light microscope?

The limit of resolution for a compound light microscope is 0.2 μm.

What are the two types of microscopy commonly used for prokaryotic cells?

Light microscopy and electron microscopy.

How does a brightfield microscope work?

A brightfield microscope allows dark objects to be visible against a bright background.

What are the two main types of electron microscopes?

Transmission electron microscopy and scanning electron microscopy.

What is the primary stain used in the Gram stain procedure?

Crystal Violet is the primary stain used in the Gram stain procedure.

What color do Gram-positive bacteria appear after the Gram stain process?

Gram-positive bacteria appear purple after the Gram stain process.

What characterizes acid-fast bacteria in staining techniques?

Acid-fast bacteria have a waxy material in their cell walls and are not decolorized by acid-alcohol.

What is the purpose of a capsule stain?

A capsule stain is used to visualize the gelatinous outer layer of bacteria that protects them and contributes to their pathogenicity.

What is the endospore stain technique used for?

The endospore stain technique is used to identify resistant, dormant structures in gram-positive bacteria.

What role does the mordant play in the Gram staining process?

The mordant, Gram iodine, fixes the color to the cell wall during the Gram staining process.

What does a negative stain technique help to observe?

A negative stain technique helps observe the presence or absence of capsules that do not take up positive or negative charged stains.

What stain is used to visualize flagella?

Carbolfuchsin is used as a mordant to thicken the appearance of flagella during the staining process.

What is the significance of the resolution (0.2 nm) in transmission electron microscopy?

A resolution of 0.2 nm allows for a clear distinction of internal structures of cells and viruses.

What does a simple stain reveal about bacterial morphology?

A simple stain determines the presence and shapes of bacteria, showing cell shape and structure.