2. Cell Fractionation Flashcards
Give two ways homogenisation is done?
Using sound waves and vibrating the cellsGrinding them in a blender
What is the order organelles come out?
Nucleus Chloroplasts Mitochondria Lysosomes ER Ribosomes
Why is microscopy useful in studying cells?
Allows us to see organelles
What do the techniques of fractionation and ultracentrifugation allow us to do?
separate organelles to study function
What happens during fractionation?
Cells broken open
What happens during ultracentrifugation?
Organelles separated
What tissue is commonly used? Why?
Liver (1) High metabolism/ lots of organelles
Why is a buffer solution used?
To maintain a constant pH
Why the solution is used isotonic?
to prevent water entering or leaving the organelles so stops them shrinking or bursting
Why is everything kept ice-cold?
To prevent enzyme activity
Which organelle contains enzymes that might damage the cells or its contents?
Lysosomes
Why is the sample homogenised
To break open cells and release organelles
Why is the homogenate filtered
To remove cell debris
Initially the homogenate is spun at low speed. Suggest what this might be.
800-1000g/ 10 mins
Why does a pellet separate out?
Some organelles are heavier and more dense
What is the first organelle to separate out?
Nuclei
Give another name for the pellet?
sediment
What is the liquid called?
Supernatant
The liquid is centrifuged again at a higher speed e.g. 3-4000g for 10 minutes. Suggest what will separate out now.
Mitochondria
Suggest a tissue you could use to obtain a sample of chloroplasts
Spinach
