Chapter 3: Microscopy Techniques and Staining in Biological Research

What is the role of the condenser in microscopy?

The condenser focuses light onto the specimen to enhance illumination.

What is the function of immersion oil in light microscopy?

Immersion oil increases the resolution by reducing light refraction between the lens and the specimen.

What are the typical resolution and magnification limits of light microscopy?

Light microscopy typically has a resolution limit of about 200 nm and a magnification limit of around 1000x.

How does bright field microscopy differ from darkfield and phase-contrast microscopy?

Bright field microscopy uses transmitted light to view specimens, while darkfield microscopy enhances contrast by scattering light, and phase-contrast microscopy enhances contrast of transparent specimens by exploiting differences in refractive index.

What are reasons for using darkfield microscopy instead of bright field microscopy?

Darkfield microscopy is used to view specimens that are nearly transparent and to enhance contrast without staining.

What can be resolved better using a phase-contrast microscope compared to a standard bright field microscope?

Phase-contrast microscopy can resolve live, transparent specimens and cellular structures that are difficult to see with bright field microscopy.

Describe fluorescence microscopy and its applications.

Fluorescence microscopy uses fluorescent dyes to label specimens, allowing for the visualization of specific structures or molecules; auramine O can be used to identify mycobacteria.

How are antibodies utilized in fluorescence microscopy?

Antibodies can be conjugated with fluorescent dyes to specifically bind to target antigens in a specimen, allowing for targeted visualization.

What disease is caused by Treponema pallidum?

Treponema pallidum causes syphilis.

What are examples of basic and acidic stains in microscopy?

Basic stains include methylene blue and crystal violet, while acidic stains include eosin and acid fuchsin; basic stains are also known as cationic stains, and acidic stains are known as anionic stains.

What are the advantages and disadvantages of electron microscopy?

Advantages include high resolution and magnification; disadvantages include the need for vacuum conditions and the inability to view live specimens.

What type of microscope is needed to see bacteriophages and why?

An electron microscope is needed to see bacteriophages due to their small size, which is below the resolution limit of light microscopy.

What are the reasons to use SEM vs. TEM?

SEM (Scanning Electron Microscopy) is used for surface imaging and 3D visualization, while TEM (Transmission Electron Microscopy) is used for internal structure analysis at higher resolutions.