Microscopy Flashcards
What is the definition of a crystal violet stain?
A salt basic dye
Crystal violet is commonly used in microbiology for staining cells.
What is an acidic dye?
A dye where the chromophore is an anion
Used in negative staining
Stains the background of the cell instead of the cell.
What is a basic dye?
A salt dye where the chromophore is a cation
Used in simple staining.
What is the purpose of a mordant in staining?
To intensify staining by helping retain the dye or coating a structure to enlarge it.
Mordants can enhance the visibility of certain structures.
ex: Iodine in gram staining
What is a smear in microbiology?
A thin film of a solution of water and microbe sample on a slide
Smears are typically heat-fixed before staining.
What does heat-fixing a smear accomplish?
Attaches the microbes to the slide and kills the microbes
Heat-fixing is a critical step in preparing slides for staining.
Why is staining performed in microbiology?
To increase cells’ contrast with the background
Most microorganisms are colorless, making staining essential for visibility.
Organisms are killed by most stains
What is immersion oil used for in microscopy?
Immersion oil is necessary for viewing specimens with certain objective lenses. It increases resolution.
Oil acts as an extension of the lens because oil has a similar refraction rate as glass.
Air causes light to refract more perpendicularly, causing some light to be lost.
Define light microscopy.
Use of any microscope that uses visible light to view a specimen
Light microscopy is one of the most common methods used in biology.
What is a compound microscope?
A microscope that uses a series of lenses to magnify specimens
Compound microscopes are widely used in laboratories.
First microscope was a compound microscope
How is total magnification calculated?
Total magnification = Magnification of objective x Magnification of ocular
This formula helps determine the overall magnification of a specimen.
What is the average size of prokaryotic cells?
Up to 2.0 µm in diameter, 8.0 µm in length
Prokaryotic cells are generally smaller than eukaryotic cells.
What does morphology refer to in microbiology?
The shape of individual cells
Understanding morphology is crucial for identifying different bacteria.
List the common bacterial morphologies.
- Coccus (cocci): Spherical
- Bacillus (bacilli): Rod-shaped
- Coccobacillus: Short, fat bacillus
- Spiral: Curved (vibrio, spirillum, spirochete varieties)
These shapes help in the classification of bacteria.
What does arrangement refer to in bacterial cells?
The characteristic pattern of attachment among cells in a species.
It is determined how cells divides.
Bacterial arrangements can indicate specific species.
What are the common bacterial arrangements?
- Diplo-: Pairs
- Strepto-: Chains
- Staphylo-: Clusters
- No arrangement: Random
These arrangements are used for identifying bacterial species.
What is a simple stain?
Use of a single, basic dye to stain the bacteria on the slide.
Simple stains are often used to quickly visualize the shape and arrangement of bacteria.
What is a negative stain?
Use of acidic dye to stain the background instead of the cells
Negative staining helps in visualizing structures without staining the cells themselves.
What differentiates differential stains from simple stains?
Differential stains react differently with different types of bacteria
This allows for the identification of specific bacterial types, and structures.
Gram-staining
Acid-fast stain
Endospore stain
Flagella staining
What does electron microscopy use instead of light?
An electron beam instead of a lightbeam.
Electron microscopy provides much higher resolution than light microscopy.
What is the resolution?
The ability of lenses to distinguish fine detail
Higher resolution allows for more detailed observations of specimens.
What is the magnification range for Scanning Electron Microscopy (SEM)?
1,000-10,000X magnification
SEM is used to view the surface of cells in 3D.
What is the magnification range for Transmission Electron Microscopy (TEM)?
10,000-100,000X magnification
TEM allows for viewing cross-sections of individual cells, allowing us to visualize organelles
What is an endospore stain?
A stain that requires heat to drive a stain into endospores
Few bacteria have an endospore. Endospore staining is important for identifying certain bacterial species.
What is required for flagella staining?
A mordant to make the flagella wide enough to see
Flagella staining is used to visualize flagella structures on bacteria.
