Cell Fractionation And Ultracentrifugation

Question 1

What does cell fractionation mean?

Answer 1

The process of breaking up and separating out the different organelles

Question 2

What does the term ultracentrifugation mean?

Answer 2

Fragments in the sample are separated by a centrifuge

Question 3

Define the importance of the sample being in a cold, isotonic and buffered solution.

Answer 3

Cold - to reduce enzyme activity and prevent damage to organelles
isotonic - to prevent organelles shrinking or busting due to osmosis
buffered - to maintain a constant and optimum pH to prevent denaturing

Question 4

Describe and explain how cell fractionation and ultracentrifugation can separate organelles from a suspension of cells.

Answer 4

• place the tissue in a cold, isotonic and buffered solution. Cold to reduce enzyme activity, isotonic to prevent organelles shrinking or bursting due to osmosis, buffered to maintain and optimum pH and prevent denaturing of the organelles or proteins.
• homogenise tissue, break up the cells using a homogeniser into a homogenate, this breaks up cells to release organelles.
• filter the homogenate, do this to remove the unbroken cells and debris from the homogenate.
• spin filtrate in centrifuge, the heaviest organelle will create a pellet at the bottom.
• pour off supernatant and spin the solution again till you reach the organelle you wish to isolate