CSU LIFE 212 Exam 2 UPDATED Actual
Questions and CORRECT Answers
bright field - CORRECT ANSWER✔✔- background is brightly lit- stained, fixed samples
(Light Microscope, compound)
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
(LM, comp)
Dark field - CORRECT ANSWER✔✔- background light is dark-opaque disk inserted
between light source and condensor (LM, comp)
Dissecting/stereoscope - CORRECT ANSWER✔✔- large working distance-used for
handling large specimens (LM)
Inverted microscope path - CORRECT ANSWER✔✔- objective lens below specimen-
condensorabove the specimen-used for tissue culture (LM)
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 (LM)
Fluorescence - CORRECT ANSWER✔✔- mercury or xenon light source-mirrors +
excitation + emission filters allow only emitted light of a specific wavelength to be seen
(LM)
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 (LM)
, Transmission Electron - CORRECT ANSWER✔✔- specimen (~100 nMthick) with
electrons◦Dense parts of the specimen do not allow electrons to pass through the
specimen.◦Cytoplasmicareas appear clear.◦Resolving Power = 3 to 10 Angstroms (A)
Best are 200000X human eye (electron microscope)
Scanning electron - CORRECT ANSWER✔✔- Used for un-sectioned specimens◦Bombards
the surface with electrons to reveal a 3D image.◦Resolving power = 30-100A (EM)
1 Angstrom - CORRECT ANSWER✔✔- 0.1nm, 10 A = 1 nm
Atomic Force Microscopy/ Scanning Tunneling - CORRECT ANSWER✔✔- Used to deduce
overall shape of single molecules in solution.◦Uses a minute probe to scan across a
surface.◦0.1 nm lateral resolution, 0.01 nm depth resolution (non-imaging)
electrical signal converted to image
X-Ray Crystallography - CORRECT ANSWER✔✔- Diffraction patterns are used to deduce
structure of individual proteins and complexes (NI)
Optical resolution/resolving power - CORRECT ANSWER✔✔- ability to distinguish
between 2 closely positioned features and resolve detail
Numerical aperture - CORRECT ANSWER✔✔- n*sina
quality of objective (part of resolving power)
range of angles over which a system accepts/emits light
function of the refractive index of the medium in which the lens works.
Best light microscopes magnify up to... - CORRECT ANSWER✔✔- 500X human eye
Human eye limit - CORRECT ANSWER✔✔- 100 um
Light microscope limit - CORRECT ANSWER✔✔- 0.2 um
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