2.1.3 Microscopy Flashcards

1
Q

Define magnification

A

How many times bigger an object appears

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2
Q

Define resolution

A

The ability to distinguish two points next to each other

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3
Q

If the resolution of a microscopic image is too low, what can be said about the light/electrons used

A

The wavelength is too long

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4
Q

Magnification equation

A

Magnification = image size / actual size

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5
Q

1cm = ?mm

A

10

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6
Q

1mm = ?µm

A

1000

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7
Q

1µm = ?nm

A

1000

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8
Q

Measurement unit conversion image

A
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9
Q

How to measure an object using a microscope and graticule

A
  • Line up graticule with object
  • Count how many epu for the measurement
  • Calibrate graticule using stage micrometer - how many µm per epu
  • Multiply the number of epu by the calibration factor
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10
Q

Resolution of optical microscope

A

Low

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11
Q

Resolution of SEM

A

Medium

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12
Q

Resolution of TEM and ADVANTAGE

A
  • High
  • Allows organelles to be seen in greater detail
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13
Q

Magnification of optical microscope

A

Low

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14
Q

Magnification of TEM

A

High

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15
Q

Magnification of SEM

A

Medium

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16
Q

How does a optical microscope work

A

Light ray focused onto object then onto eye using glass lenses

17
Q

How does a SEM work

A
  • Electrons deflected/bounce off specimen
  • Foccused by electromagnets
18
Q

How does a TEM work

A
  • Electrons transmitted/pass through specimen
  • Foccused by electromagnets
19
Q

Primary use of optical microscope

A

Study living cells

20
Q

Primary use of SEM

A

View 3D image

21
Q

Primary use of TEM

A

View cell ultrastructure

22
Q

Are optical microscope images in colour

23
Q

Are TEM images in colour

24
Q

Are SEM images in colour

25
Non-limitations to optical microscopes
* Can be dead or alive * No vacuum * Not too thin * Stained with dye * No artefacts * Doesn't take too long
26
Limitations to SEM
* Must be dead * In vacuum * Very thin specimin * Stained with metal * Artefacts may occur * Time consuming
27
Limitations to TEM
* Must be dead * Must be in vacuum * Specimin must be very thin * Stained with metal * Artefacts may occur * Time consuming
28
In microscope images, if the resolution is high/low what can be said about the light or electrons wavelength
* Low resolution = long wavelength * High resolution = short wavelength
29
Describe how to extract chloroplast from a cell sample
* **Homogenise** cells in homogeniser * **Filter** to remove unbroken cells/debris * Place homogenate in test tube and spin in a **centrifuge** at **low** speed * Remove nuclei pellet at bottom * Respin **supernatant** in new test tube at **higher speed** * Remove chloroplast pellet
30
When extracting organelles from cells during ultracentrifugation, what is the order of heaviest organelles, that must be removed
* Nuclei * Chloroplast - **only if plant cell** * Mitochondria
31
When extracting organelles from cells, why must the solution be cold
Reduce enzyme activity, so organelles aren't digested
32
When extracting organelles from cells, why must the solution be isotonic
Prevent water movement into organelles by osmosis - preventing lysis
33
When extracting organelles from cells, why must the solution be pH buffered
* Maintain pH * Prevent denaturations of proteins and enzymes