Chapter 4 - Microscopy, Staining, Classification Flashcards
Why is the metric system used in science?
The metric system is a decimal system. Each unit is one tenth the size of the next smallest unit. This makes dealing with very small units easier than the English system.
One thousandth of a millimeter
micrometer
One thousandth of a micrometer
nanometer
the distance between two corresponding parts of a wave of a radiation beam
wavelength
Increase in the apparent size of an object
magnificiation
refraction
the bending of light
why does a lens bend light
the leading edge of the light beam slows as it enters a lens and the beam bends. Light also bends as it leaves the lens and reeenters the air.
the ability to distinguish two points that are close together
resolution
Formula for resolution
resolution = 0.61 X wavelength/numerical aperture
the ability of a lens to gather light
numerical aperature
Differences in intensity between two objects or between and object and its background
contrast
Microscope with single lens
simple microscope
microscope with multiple lenses
compound microscope
lenses closest to the eyes
ocular lenses
total magnification
objective lens magnification X ocular lens magnification
directs light through a specimen
condenser lens
a microscopic image
micrograph
microscope that uses an ultraviolet light to fluoresce objects
fluorescent microscope
microscope that uses fluorescent dyes or stains and ultraviolet lasers
confocal microscope
microscope that generates a beam of electrons that ultimately produce an image on a computer screen.
transmission electron microscope
Disadvantages of scanning and transmission electron microscope
Requires a vacuum, so the organism to be scanned must be dead
microscope that passes a beam of electrons across a surface
scanning electron microscope
microscope which measures the flow of electrons to and from a probe and the surface of a specimen
scanning tunneling microscope
microscope that traverses the tip of a pointed probe across the surface of a specimen
atomic force microscope
staining
coloring specimens with stains
thin film of organisms on a slide
smear
positively charged dye that stain acidic surfaces. work best in high pH
basic dyes
dyes that stains alkaline structures
acidic dye
Distinguishes between purple staining gram-postive cells and pink gram-negative cells
Gram stain method
colors all cells
primary stain
binds to a dye and makes it less soluble
mordant
breaks down the cell wall of Gram-negative cells, allowing the stand and mordant to be washed away
decolorizing agent
works on cells with thick lipid layer in their cell wall
acid fast staining
dormant cells, highly resistant to destruction
endospores
a stain that stains the background behind a cell because it does not bind with negatively charged cells
negative stain
what is a negative stain used for?
mostly to identify negatively charged bacterial capsules
