Ch3 Microscopes Flashcards

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1
Q

Magnification formula

A

image size / actual size

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2
Q

Magnification

A

how much larger the image size compared to the actual size

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3
Q

Resolution

A

minimum distance at which two objects are to be seen as separate

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4
Q

Cell fractionation conditions

A
  1. cold to reduce enzyme activity
  2. isotonic- same wpt so organelle doesn’t shrink or burst
  3. buffer- maintains constant pH
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5
Q

cell fractionation

A
  1. break down tissue into cells using pestle and mortar
  2. add solution
  3. homogenate to release organelles
  4. filter to remove large debris
  5. centrifuge
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6
Q

Ultracentrifugation

A
  1. filtrate spun at speed
  2. heaviest organelles forced to the bottom of the tube
  3. supernatant fluid at top is removed
  4. repeat at higher speeds
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7
Q

Heaviest to lightest organelles

A
  1. nuclei
  2. chloroplast
  3. mitochondria
  4. endoplasmic reticulum
  5. golgi body
  6. lysosomes
  7. ribosomes
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8
Q

Difference between TEM and SEM

A
  1. TEM uses electrons passing through specimen
  2. SEM uses electrons bounding off specimen surface
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9
Q

Advantage of electron microscopes

A
  1. electron beam has shorter wavelength
  2. higher resolving power
  3. beam can be focused with electromagnets
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10
Q

Advantage of TEM

A

highest magnification
highest resoluiton

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11
Q

Disadvantage electron microscopes

A
  1. vacuum condition requires thin dead specimens
  2. black and white
  3. 2d image
  4. artefacts
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12
Q

Advantage SEM

A

produces 3D image

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13
Q

Electron microscope conditions

A

vacuum so electrons can’t be absorbed or deflected by molecules in air

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14
Q

Reason TEM resolving power can’t be achieved

A
  1. difficulty preparing specimen
  2. higher electron energy beam may destroy specimen
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