Topic 3 Flashcards
What microscopy techniques are used to view live cells?
Dark field Phase Contrast Fluorescent Confocal Laser scanning Atomic Force
What is Dark Field Microscopy?
the visualization through a microscope of live microbes as halos against darkness
What is Fluorescence Microscopy?
the visualization of live 3D microbes that have absorbed light and are releasing light of a greater wavelength
What is confocal laser scanning microscopy?
a type of fluorescent microscopy where a live sample is scanned by a laser to reveal 3D topography
What is atomic force microscopy?
uses a probe to measure the vanderwaal forces of the surface of a live microbe
What microscopy techniques can be used to view the components inside of a cell?
phase contrast
fluorescence
Transmission EM
cyro-electron
What microscopy techniques can be used to view the 3D topography of a living or fixed cell?
fluorescent confocal laser (live only) atomic force scanning EM (fixed only) cyro-electron (fixed only)
Why are heavy metals used in electron staining?
heavy metals are used because the samples lack electron density and are unable to scatter electrons; heavy metals settle on the surface of the sample which is where to electrons will scatter so the structure can be outlined
Rank light microscopy, electron microscopy, atomic force microscopy, and X-ray crystallography in from least to greatest resolution?
light microscopy, electron microscopy, atomic force microscopy, and x-ray crystallography
What is bright-field microscopy?
the microbes are stained (fixed) dark against a bright field, can resolve up to 1000x
How are gram-positive and negative cells identified?
gram-positive - appears purple due to thicker cell wall
gram-negative - appears pink due to thinner cell wall
Give an example of a spore stain.
Malachite green
What is phase-contrast microscopy?
exploits the differences in refractive indices between cytoplasm and organelles of live microbes
What is transmission electron microscopy (TEM)?
specimen is fixed and spliced into thin sections so they electrons passing through can reveal internal structure
What is scanning electron microscopy (SEM)?
electrons scan the surface of a metal-fixed specimen to reveal 3D features
