Life 212 Final UPDATED Actual Questions
and CORRECT Answers
Bright field - CORRECT ANSWER✔✔- - background is brightly lit
- stained, fixed samples
Phase contrast - CORRECT ANSWER✔✔- - transparent, unstained samples
-special lenses (annular stop turret in our lab
exercises)
-background light is separated from the light diffraction pattern generated by the specimen
Dark field - CORRECT ANSWER✔✔- -background light is dark
-opaque disk inserted between light source and condensor
Dissecting (or stereoscope) - CORRECT ANSWER✔✔- -large working distance
-used for handling large specimens
Inverted - CORRECT ANSWER✔✔- -objective lens below specimen
-condensor above the specimen
-used for tissue culture
Differential Interference Contrast - CORRECT ANSWER✔✔- -separates polarized light into
two beams
-the length of each optical path differs, which gives the appearance of a 3D relief
- uses Nomarski optics
Fluorescence - CORRECT ANSWER✔✔- -compound or inverted
-mercury or xenon light source
-mirrors + excitation + emission filters allow only
emitted light of a specific wavelength to be seen
, Confocal - CORRECT ANSWER✔✔- - a special type of fluorescence scope
-software allows digital capture of image slices.
-multiple images across the vertical Z axis are
captured and reassembled in 3D reconstructions
-reduces background fluorescence from unfocused parts of the specimen
Transmission Electron - CORRECT ANSWER✔✔- ◦Uses high energy electron beam to
bombard thin specimen (~100 nM thick) with electrons
◦Dense parts of the specimen do not allow electrons to pass through the specimen.
◦Cytoplasmic areas appear clear. ◦Resolving Power = 3 to 10 Angstroms (A
Scanning electron - CORRECT ANSWER✔✔- ◦Used for un-sectioned specimens
◦Bombards the surface with electrons to reveal a 3D
image.
◦Resolving power = 30-100A
Atomic Force Microscopy - CORRECT ANSWER✔✔- Used to deduce overall shape of
single molecules in solution with a vertical resolution of ~0.1 nm
Scanning tunneling - CORRECT ANSWER✔✔- ◦Uses a minute probe to scan across a
surface.
◦0.1 nm lateral resolution, 0.01 nm depth
resolution
X-Ray Crystallography - CORRECT ANSWER✔✔- ◦Diffraction patterns are used to deduce
structure
of individual proteins and complexes
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