Chapter 3 - Observing Microorganisms Flashcards
cm
Centimeter- 1/100 = 0.01 m (meters) = 10^-2
mm
Milimeters - mili = 1/1000 = 0.001 m = 10^3 m
āuām
Micrometer - 1/1,000,000 = 0.000001 m = 10^-6
nm
Nanometer - nano = 1/1,000,000,000 = 0.000000001 m = 10^-9
Total magnification
Objective lens multiplied by ocular lens
Resolution
The ability of the lenses to distinguish two points
Greater resolution is given when provided what?
shorter wavelengths of light
Objective lens
The lenses closest to the specimen
Ocular lens
Eyepiece
Brightfield illumination
Dark objects are visible against bright background, what is primarily done in lab course. Brightfield illumination shows internal structures and the outline of the transparent external covering or pellicle
Fluorescence microscopy
Uses UV, shortwave wavelength , light. Fluorescence substances absorb UV light and emit longer wavelength ,visible, light
Transmission electron microscopy
A beam of electrons passes through ultrathin sections of a specimen, then through and electromagnetic Lens, then focused on a projector lens. Specimens May be stainedwith heavy metal salts for contrast
Scanning electron microscopy
And electron gun produces a beam of electrons That scans the surface of an entire specimen, secondary electrons emitted from the specimen produce a three-dimensional image.
Staining
Coloring Microorganisms with a dye that emphasizes certain structures
Mordant
Maybe used to hold the stain or coat the specimen to enlarge it. Example. Iodine
Gram staining
Classifies bacteria into gram-positive or gram-negative
Gram-positive
Bacteria that have thick peptidoglycan cell walls
Gram-negative
Bacteria that have thin peptidoglycan cell walls and a layer of polysaccharides
Acid-fast staining
Binds only to bacteria that have waxy material in their cell walls
What are the two terms that are used to identify acid-fast stain?
Mycobacterium and nocardia
endospore stain
Resistant, dormant structures inside some cells that cannot be stained by ordinary methods. Primary stain = Malachite green, usually with heat/Steam
Capsule stain
Capsules are a gelatinous covering that do not accept most dyes, India ink or nigrosin contrast the background with the capsule
