Ch3 Microscopes Flashcards
1
Q
Magnification formula
A
image size / actual size
2
Q
Magnification
A
how much larger the image size compared to the actual size
3
Q
Resolution
A
minimum distance at which two objects are to be seen as separate
4
Q
Cell fractionation conditions
A
- cold to reduce enzyme activity
- isotonic- same wpt so organelle doesn’t shrink or burst
- buffer- maintains constant pH
5
Q
cell fractionation
A
- break down tissue into cells using pestle and mortar
- add solution
- homogenate to release organelles
- filter to remove large debris
- centrifuge
6
Q
Ultracentrifugation
A
- filtrate spun at speed
- heaviest organelles forced to the bottom of the tube
- supernatant fluid at top is removed
- repeat at higher speeds
7
Q
Heaviest to lightest organelles
A
- nuclei
- chloroplast
- mitochondria
- endoplasmic reticulum
- golgi body
- lysosomes
- ribosomes
8
Q
Difference between TEM and SEM
A
- TEM uses electrons passing through specimen
- SEM uses electrons bounding off specimen surface
9
Q
Advantage of electron microscopes
A
- electron beam has shorter wavelength
- higher resolving power
- beam can be focused with electromagnets
10
Q
Advantage of TEM
A
highest magnification
highest resoluiton
11
Q
Disadvantage electron microscopes
A
- vacuum condition requires thin dead specimens
- black and white
- 2d image
- artefacts
12
Q
Advantage SEM
A
produces 3D image
13
Q
Electron microscope conditions
A
vacuum so electrons can’t be absorbed or deflected by molecules in air
14
Q
Reason TEM resolving power can’t be achieved
A
- difficulty preparing specimen
- higher electron energy beam may destroy specimen
