Cell fractionation and ultracentrifugation

Question 1

What is cell fractionation and ultracentrifugation?

Answer 1

Breaking down a cell to isolate organelles to give scientists information about the structure

Question 2

Step 1) cell fractionation and ultracentrifugation

Answer 2

The tissue is homogenised in a blender (e.g liver, heart or leaf) in ice-cold, isotonic and buffered solution to break open the cells and release the organelles

Question 3

Step 2) Cell fractionation and ultracentrifugation

Answer 3

The mixture is filtered to remove any large prices of tissue/cells/debris that’s not broken up by the homogeniser producing a solution of suspended organelles (supernatant)

Question 4

Step 3) Cell fractionation and ultracentrifugation

Answer 4

Differential centrifugal ion is carried out in the supernatant
•Starts off at a low speed for the densest organelles e.g. the nucleus
•They are forced to the bottom of the tube into a pellet, this pellet is removed and the solution above the pellet is the supernatant

Question 5

Step 4) Cell fractionation and ultracentrifugation

Answer 5

Supernatant is now centrifuges at a higher speed for smaller, less dense organelles that are forced to the bottom of the tube into a pellet. Pellet is removed and the supernatant is centrifuged at an even higher speed

Question 6

Step 5) Cell fractionation and ultracentrifugation

Answer 6

Process repeated as many times as needed at higher speeds each time to separate them according to their density

Question 7

How can you confirm the presence of an organelles in a pellet?

Answer 7

Use a microscope

Question 8

Most dense organelle

Answer 8

Nucleus

Question 9

Second most dense organelles

Answer 9

Mitochondria and chloroplasts

Question 10

Least dense organelle

Answer 10

Ribosomes