Microscopy Flashcards

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1
Q

What is the equation for magnification?

A

Magnification = image size/ actual size

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2
Q

What is magnification?

A
  • the degree to which the size of an image is larger than the object itself
  • too high, can result in blurred image
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3
Q

What is resolution?

A
  • the ability to see two distinct points separately that are very close together
  • increases the level of detail
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4
Q

How do you calculate total magnification?

A

eyepiece x objective

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5
Q

What is staining?

A

Using chemicals that react with other chemicals in the sample to…

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6
Q

What is sectioning?

A

Using wax to stop the structure of the specimen from being distorted

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7
Q

Describe an electron microscope:

A
  • uses beam of electrons with a wavelength of 0.004nm
  • resolution = 0.1nm (500,000x greater than human eye)
  • uses magnets to focus
  • creates an electron micrograph
  • allows us to image viruses and DNA, which are smaller than 200nm
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8
Q

What is an electron micrograph

A

an image on a screen or photographic paper created by an electron microscope

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9
Q

Describe optical microscopes

A
  • magnification: x1500
  • resolution: 200nm
  • method: light beams pass via object
  • image type: 2D
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10
Q

Describe SEM

A
  • magnification = x100,000
  • resolution = 1nm
  • method: electron beam reflects off object’s surface; directed onto sample
  • image type: 3D
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11
Q

Describe TEM

A
  • magnification: x500,000
  • resolution: 0.05nm
  • method: electron beam passes through sample
  • image type: 2D (the darker the parts seen, the thicker the sample)
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12
Q

Describe a TEM image

A

Slices through a plane of view which can be at any angle through any part of an organelle

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13
Q

Pros of an optical microscope:

A
  • can see colour
  • easy to use
  • accessible
  • relatively cheap
  • do not need a vacuum; can observe a living sample
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14
Q

Cons of an optical microscope:

A

Low resolution and magnification; low retail

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15
Q

Pros of an electron microscope:

A

electrons have a smaller wavelength (up to 100,000x) therefore there is a higher magnification and higher resolution

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16
Q

Cons of an electron microscope

A
  • cannot see colour
  • requires skill and training to use
  • inaccessible
  • relatively expensive
  • needs a vacuum- cannot observe a living sample
  • requires greater preparation time (days)
  • electrons can bounce off air
17
Q

How to use an electron microscope:

A
  • fix the specimen
  • dehydrate
  • cut into thin slices
  • stain
  • mount onto copper grid
  • place in vacuum in the microscope
18
Q

How do you calibrate the eyepiece graticule?

A

???

19
Q

Units

A
cm = 1/100th m
mm = 1/1000th m
μm = 1/1000000 m
nm = 1/1000000000 m