Microscopy Flashcards
Resolution
Determines the smallest object a person can see, distance between 2 foveal fixes, 150 unit apart
What magnification are eukaryotes?
10-100 um
What magnification are prokaryotes?
0.4-10 um
What are some contradictions of microscopy?
microbes function as communities, some viruses are as large as bacteria, some communities should be studied as whole
Define Light Microscopy.
resolves images according to light absorption
Define Electron Microscopy.
uses beams of electrons for smaller details
Define Atomic Force Microscopy.
uses intermolecular forces to map 3D-topography
Define X-Ray crystallization.
detects the interference patterns of X-Rays entering a molecule
How many nanometers is visible light?
400-700nm
What conditions must exist for electromagnetic radiation to resolve an object?
1) wavelength of radiation must be equal or smaller than size of object
2) contrast between the object and its background
3) detector for significant resolution for given wavelength
What type of microscopy has a resolution of 1000x?
bright field
What does oil immersion do?
minimizes loss of reflected light, sharpens image
Gram-positive.
retains the violet stain because of thicker cell wall
Gram-negative.
stains cells red/pink
What are the 4 fates when light interacts with an object?
1) absorption
2) reflection
3) refraction
4) scattering
What is phase contrast microscopy?
differences in refractive index between cytoplasm and surrounding medium (patterns of light and dark)
Define fluorescence microscopy.
when the specimen absorbs light of defined wavelength and emits light of longer wavelength, allows observation of live microbes in real time
Define autofluorescence.
some cell components are naturally fluorescent
Define fluorophores.
fluorescent chemical compounds with specificity for cellular target
What are the 4 parts of fluorophores?
1) chemical affinity
2) labelled antibody
3) DNA hybridization
4) gene fusion tags
How does confocal microscopy work?
scanned by laser light to reveal topography
What type of electron microscopy is sliced into 2D?
transmission (more than 1000x)
What type of electron microscopy is unsliced into 3D?
scanning (more than 1000x)
What is cryo-scanning?
high strength electron beams that permit low temperature imagine without specimen staining
