Cell Fractionation

Question 1

What does homogenisation do to the cell?

Answer 1

It breaks up the plasma membrane so the organelles are released in a special isotonic, ice-cold, buffered solution

Question 2

Why must the solution be isotonic, ice-cold and buffered?

Answer 2

Isotonic: stops osmosis to prevent damage to organelles
Buffered: maintains the pH
Ice-cold: reduce enzyme activity

Question 3

What does filtration do?

Answer 3

Removes large cell debris or tissue debris by filtering the solution through a gauze

Organelles are smaller than debris and pass through the gauze

Question 4

What is Ultracentrifugation?

Answer 4

Solution is spun at a low speed.
Heavy organelles go to the bottom of the tube and forms a pellet

The supernatant is then removed from the top and spun at a higher speed etc

(This process repeats)

Question 5

What order do the organelles seperate

Answer 5

They separate in order of mass

```
Nuclei
Chloroplasts
Mitochondria
Lysosomes
Endoplasmic reticulum
Ribsomes
~~~

Question 6

What are the 3 steps in cell fractionation?

Answer 6

Homogenisation
Filtration
Ultracentrifugation