Chapter 2: Microscopy Flashcards
The smallest distance by which 2 objects can be separated and distinguishable
Resolution
The size at which objects become visible depends on…
The resolution of the observer’s eye
The resolution of the human retina
150um
The ability to determine the presence of an object
Detection
The approx range in size of eukaryotic microbes
10-100um
The approx range in size of prok microbes
0.4-10um
4 common shapes of bacteria
- Bacilli
- Cocci
- Spirochetes
- Spirella
_______ occurs when the wavefront interacts with an object smaller than the wavelength of light
Scattering
Generates a dark image of an object over a light background
Bright-field microscopy
5 ways to increase resolution
- Use shorter wavelength
- Lessen contrast
- Use immersion oil
- Use wider lens closer to specimen
- Higher numerical aperture
Does a shorter or longer wavelength increase resolution?
Shorter
A system of multiple lenses designed to correct or compensate for aberration
A compound microscope
When a microscope stays focused after objectives are switched it is…
Parfocal
Advantage of wet mount
Observation of cells in a natural state
Disadvantages of wet mounts
Low contrast
Sample may dry up quickly
Simple stain
Adds dark color to the cells but not external media or surrounding tissue
Stains one kind of cell and not another
A differential stain
Colors the background, making the capsule more visible
Negative stain
Carbolfuchsin used to stain mycobacterium
Acid-fast stain
Uses malachite green
Spore stain
