Methods of studying cells

Question 1

magnification

Answer 1

size of image divided size of real object

Question 2

resolution

Answer 2

minimum distance apart that two objects can be in order for them to appear as separate items

Question 3

cell fractionation

Answer 3

process where cells are broken up and the different organelles they contain are separated out

Question 4

Properties of solution:

Answer 4

cold - reduce enzyme activity that might break down organelles
isotonic - prevent organelles bursting or shrinking as a result of osmosis
buffered - so pH does not fluctuate

Question 5

Homogenation

Answer 5

Cells blended into a homogenate and is then filtered in order to remove debris

Question 6

Ultracentrifugation

Answer 6

spins tubes of homogenate at very high speeds in order to create centrifugal force.

Question 7

Steps of Ultracentrifugation

Answer 7

• tube is spun at low speed
• heaviest organelles are forced to the bottom where they form a sediment
• fluid at top is removed (supernatant) leaving just sediment of nuclei
• supernatant is transferred to another tube and spun at a faster speed
• next heaviest mitochondrian are forced to the bottom

Question 8

organelles and speed of centrifugation

Answer 8

nuclei = 1000
mitochondria = 3500 
lysosomes = 16500

Question 9

Optical microscope

Answer 9

• poor resolution
• ## long wavelength of light

Question 10

transmission/scanning electron microscope

Answer 10

LIMITATIONS

• must be under vacuum so specimens dead
• specimen extremely thin
• image may contain artifacts

Question 11

Differences

Answer 11

SEM can create 3D images and color