Cell fractionation Flashcards
Define cell fractionation
Process where cells are broken upon and the different organelles they contain are separated out
Before cell fractionation what type of solution is the tissue placed in
Before cell fractionation the tissue is placed in a cold buffered solution (of the same water potential as the tissue)
Why is the solution cold
To reduce enzyme activity that might break down the organelles
Why is the solution the same water potential as the tissue
To prevent the organelles bursting/shrinking as a result of osmotic gain/loss of water
Why is the solution buffered
So that the pH doesn’t fluctuate as this could alter the structure of organelles or affect the functioning of enzymes
What are the 2 stages to cell fractionation
Homogenation
Ultracentrifugation
Explain what happens during the process of homogenation
The cells are broken up by a homogeniser. This releases the organelles from the cell
The homogenate is then filtered to remove any complete cells and large pieces of debris
Explain what happens during ultracentrifugation
The filtrate is placed in a tube and then put in the centrifuge.
This is then centrifuged at low speeds to form pellet (rich in nuclei) at the bottom of the tube (made from the heaviest organelles)
The previous supernatant is then centrifuged at medium speed to form a pellet rich in mitochondria at the bottom of the tube
The previous supernatant is then centrifuged at high speeds to form a pellet rich in lysosomes
How has this technique allowed advances in biological knowledge
As it allows a detailed study of the structure and function of organelles by showing what the isolated components do
