Cell Fractionation Flashcards
What is cell fractionation?
The process where cells are broken up and the different organelles are separated out
What happens before cell fractionation can begin?
The tissue is placed in a cold, buffered solution of the same water potential as the tissue (to prevent osmosis)
What is the solution like that the tissue is placed in to before cell fractionation?
Cold, buffered, and of the same water potential as the tissue
Why is the solution cold?
To reduce enzyme activity that may break down the organelles (digestive enzymes from the lysosomes)
Why is the solution of the same water potential as the tissue?
To prevent organelles from bursting (lyse) or shrinking as a result of osmotic gain or loss of water
What is hypotonic?
Dilute solution (lots of water)
What is hypertonic?
Concentrated solution i.e. lots of solute
What are the two stages to cell fractionation?
Homogenation and ultracentrifugation
What is homogenation?
Cells are broken up by a blender which releases the organelles (e.g. pestle and mortar)
The homogenate is then filtered
Why is the homogenate filtered?
To remove any debris and incomplete cells
What is ultracentrifugation?
The homogenate is separated in a machine called a centrifuge. This spins homogenate at a very high speed
What will happen to an animal cell in centrifugation?
The heaviest organelles (nuclei) are forced to the bottom of the tube forming a pellet
The fluid at the top of the tube is removed (supernatant) and is then transferred to another tube and then centrifuged again
What is the medium weight organelle?
Mitochondria
What is the lightest organelle?
Ribosomes
