module 2 - 2.3 more microscopy Flashcards

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1
Q

what are the main components of a light microscope?

A

they have 2 lenses which reduced chromatic abberation
typical magnification 1500x (theoretical resolution)

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2
Q

why do light microscopes have 2 lenses?

A

to reduce chromatic abberation

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3
Q

what are the disadvantages of light microscopy?

A
  • increased magnification
  • increased resolution NOT easily achieved (due to limit of resolution of 200nm/0.2μm
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4
Q

what are the advantages of electron microscopy?

A
  • electrons can be waves or particles, wave particle duality
  • resolution from 0.5nm to 10nm
  • electron microscopes allow cells ultrastructure to be seen
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5
Q

what are the 2 types of electron microscopes?

A

transmission electron microscope (TEM)
scanning electron microscope (SEM)

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6
Q

what are the components of a transmission electron microscope?

A
  • sample embedded in resin, stained with heavy metal compounds & cut into thin sections in ultramicrotome
  • specimen is ultra-thin section, between 70-350nm
  • beams of electrons in vacuum are transmitted through sample
  • image magnified and focused onto an imaging device
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7
Q

what are 3 examples of imaging devices?

A

fluorescent screen, layer of photographic film, or sensor

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8
Q

what are the components of a scanning electron microscope?

A
  • produces image of sample by scanning surface with beam of electrons in a vacuum
  • electrons interact with atoms
  • covered with electrically conducting material
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9
Q

what is an artefact?

A

visual anomalies during visual representation

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10
Q

what is a mesosome?

A

they are invaginations in the plasma membrane of bacteria
produced by chemical fixation techniques

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11
Q

what are some differences between light and electron microscopes?

A

LIGHT- inexpensive to buy and operate, small and portable, simple sample prep, no vacuum required, natural colour/ stain, living specimen
ELECTRON - expensive to buy and operate, large and installed, complex sample prep, vacuum required, black and white image, dead specimen

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12
Q

what are some components of laser scanning confocal microscopes?

A
  • optical microscope
  • single focused light from a laser is moved across the specimen, causes fluorophores in the specimen to fluorescence
  • higher optical resolution and contrast
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