cell fractionation and ultracentrifugation Flashcards
(13 cards)
What does centrifugation separate?
Structures of different densities
What does differential centrifugation involve?
Centrifuging at different speeds to separate the different organelles in a cell
How are the cells first broken open?
By grinding (homogenising) a tissue in a cold, isotonic buffer solution using a blender
Why is an isotonic solution used?
It prevents the osmotic water movement in or out of organelles causing them to burst or shrivel
Why is a low temperature used?
It prevents the action of enzymes which might cause the self-digestion of the organelles
Why is a buffer solution used?
It maintains the pH so that proteins, particularly enzymes, are not denatured
What is centrifugation?
The filtering of cell debris
Why is centrifugation used?
It removes cell debris that have not burst in homogenisation
What happens in the first stage of centrifugation?
The homogenate is centrifuged at a low speed - the nuclei form a pellet at the bottom of the tube
What is the part above the pellet called?
The supernatant liquid
What is different about the second spin?
It is faster and longer
What is collected in the second spin?
Mitochondria if animal tissue, chloroplasts if plant tissue
What is collected in the third spin?
Endoplasmic reticulum
