cell fractionation

Question 1

what is cell fractionation

Answer 1

-The technique of separating the different organelles in a cell to have a pure sample in order to study cells and organelles

Question 2

what are the 3 steps of cell fractionation?

Answer 2

-Homoginasation
-Filtration
-Differential centrifugatiom

Question 3

what is homogenisation

Answer 3

-Breaks open cell membrane or cell wall of sample

Question 4

why must the homogenate be filtered after homogenization?

Answer 4

-To remove cellular debris, fragments of cell membrane or cell wall and anything left behind
If we didn’t filter these out, our samples of organelles may contain cellular debris that has equal density of an organelle.

Question 5

what 3 conditions must be kept at the processes of homogenisation

Answer 5

-Ice cold : To stop lytic enzyme activity
-pH buffered : To prevent further damage to organelles because organelles are sensitive to change in pH.
-Isotonic : To prevent osmotic lysis, this means that the solution we spin the organelles has to be at the same water potential as the cells themselves.

Question 6

what is a hemogenate

Answer 6

-a suspension of cell fragments obtained when tissue is homogenized.

Question 7

how does Differential centrifugation work

Answer 7

-Organelles have different densities, so some are heavier than others.
So by spinning the samples at different speeds we can separate out the more dense ones than the less dense organelles.

Question 8

what is a pellet and a supernatent

Answer 8

• Pellet: precipitated form of particles
• Supernatent: remaining solution or medium

Question 9

what is the order that organelles get separated at

Answer 9

• Nuclei
• Chloroplasts (if using plant tissues)
• Mitochondria
• Lysosomes
• Endoplasmic reticulum
• Ribosomes