Methods Of Studying Cells Flashcards
1
Q
How does a SEM work?
A
- Scan a beam of electrons across specimen.
2
Q
Features of a Optical microscope
A
- Uses light
- Can only distinguish between 2 objects that are 0.2µm apart
- Magnification is 1500x
3
Q
Features of an electron microscope
A
- Use electrons to form an image
- Shorter wavelength - can distinguish between two objects that are 0.1µm apart.
- Magnification is x 1,500,000
4
Q
What are the 2 types of microscope?
A
- Light microscope (optical microscope)
- Electron Microscope (beam of electrons)
5
Q
Advantages and Disadvantages of TEM
A
Adv:
-High resolution
Dis:
- Only used on thin specimens that are non-living.
- Complex staining process involved.
6
Q
What is an artefact?
A
- Things that result from the way the specimen is prepared e.g. dust or air bubbles.
7
Q
How does a TEM work?
A
-Uses electromagnets so electrons go THROUGH the cell
-Electrons are absorbed at denser parts of the cell making the cell darker.
-Parts of the image are lighter meaning the electrons have passed through.
8
Q
Advantages and the single disadvantage of SEMs
A
Adv:
- 3D
- Scan thick surfaces
- Coloured
Dis:
- Low resolution (still 10 x better than a light microscope.
9
Q
What is resolution? (Resolving Power)
A
- Resolution is the minimum distance apart that 2 objects can be to appear as separate objects.
10
Q
What is magnification?
A
- How many times bigger the image is than the specimen
