L3 + Chp 3 Flashcards
How are microorganisms measured?
micrometers (μm) and nanometers (nm)
How many nanometers is 10 μm?
1000nm/1 μm x 10nm = 10,000 nm
What is Light microscopy?
uses visible light to observe specimen
What are the 6 different types of light microscopy?
- compound light microscopy
- darkfield microscopy
- phase contrast microscopy
- differential interference contrast microscopy
- fluorescence microscopy
- confocal microscopy
What is compound light microscopy?
objective lens is magnified bu the ocular lens
What is the total magnification of a microscope w/ a 40X objective lends and a 10X ocular lens?
400X
What is total magnification regarding compound light microscopy?
objective lens x ocular lens
What is resolution regarding compound light microscopy?
the ability of the lenses to distinguish two points
do short or long wavelengths of light provide greater resolution?
shorter wave lengths
What is refractive index regarding compound light microscopy?
measure of light-bending ability of a medium
what is used to keep light from refracting?
immersion oil
what is brightfield illumination regarding compound light microscopy?
common type light microscopy
- dark objects visible against bright background
- light reflected off specimen DOES NOT enter objective lens
Through what lenses doe slight pass in a compound microscope
condensor, objective, ocular lenses
What is Darkfield microscopy?
light objects visible against dark background
What is Phase contrast microscopy?
allows examination of living organisms and internal cell structure
brings together two sets of light rays, direct rays, and diffracted rays to form an image
What is differential interference contrast microscopy?
uses two light beams and prisms to split light beams = more contrast and color to the specimen
What is fluorescence microscopy
uses short wavelength UV light
- absorbs UV light and emit longer wavelength
- cells may be stained w/ fluorescent dyes
What is Confocal microscopy
- cells are stained with fluorochrome dyes
- short wavelength (blue) light is used to excite a signle plane of a specimen
What is super resolution light microscopy
uses two laser beams
1 stimulates fluorescent molecules to glow
2 cancels out all fluerescence
What is electron microscopy
- uses electrons instead of light
- shorter wavelength
- used for images too small to be seen w/ light
WHat is scanning electron microscopy
produces a beam of electrons that scans the surface of an entire specimen
- emitted from the specimen produce a 3 dimensional image
- magnifies objects 1,000 to 500,000
What is Staining
coloring microorganisms w/ a dye that emphasizes certain structures
What is a Smear
thin film of a material containing microorganisms spread over a slide
What is a Chromophore
stains consisting of a positive and negative ion, one of which is colored
What is a basic dye in staining?
a salt in which the color is in the positive ion; used for bacterial stains
What are acidic dyes?
a salt in which the color is in the negative ion; used for negative staining
What is negative staining?
coloring the background instead of the cell
What is a mordant?
substance added to a staining solution to make it stain more intensely
What is a differential stain?
stain that distinguishes objects on the basis of reactions to the staining procedure
What is a gram stain?
differential stain that classifies bacteria into two groups, gram positive and gram-negative
What are gram-positive bacteria?
bacteria that retain crystal violet color after decolorizing by alcohol; they stain dark purple
What are gram-negative bacteria?
bacteria that LOSE the crystal violet color after decolorizing by alcohol; they stain red after treatment w/ safranin
What is an Acid fast stain
differential stain used to identify bacteria that are not colorized by acid-alcohol
What is acid fast stain used for?
Identification of
- mycobacterium tuberculosis
- nocardia
What are special stains?
used to color parts of microorganisms, like endospores, flagella, or capsules
What is a capsule? What is a capsule stain?
gelatinous covering composed of a polysaccharide or polypeptide that does not accept most dies.
capsule stain: suspension of india ink or nigrosin that contrasts the background with the capsule, which appears as a halo around the cell
What is Endospore spore staining
resistant, dormant structures inside some cells that cannot be stained by ordinary methods
What is a Flagella stain
- structures of locomotion
- uses a mordant and carbolfuchsin to thicken appearance of flagella, making them visible under the light microscope
How do unstained capsules appear? Stained capsules?
What does it mean when a microscope has a resolution of 0.2 nm?
