How to explain homogenisation and ultracentrifugation

Tissue must be prepared in an ICE COLD, ISOTONIC, BUFFER Solutionwhy?Isotonic solution prevents organelles from being damaged by osmosis of water moving in and out of the organelle.ice cold: lower enzyme activity so organelles aren’t digestedbuffer: maintains a constant Internal PH preventing the denaturing of enzymes as the hydrogen bonds and ionic bonds remain intact.We then homogenise (place in blender) to break cell membrane and cell walls (if plants) to release the organelles resulting in homogenate (fluid containing complete cells)filtration of this fluid then occurs to remove debriscentrifugation is where filtrate is placed in centrifuge are low speedheaviest organelles are displace first ( nucleus is heaviest, then chloroplast, mitochondria SER/RER, Golgi apparatus, lysosomes, ribosomes) heaviest organelle is removed first.Once first organelles removed, supernatant placed in another tube and this is repeated at a faster speed until all organelles are separated. (I would draw diagrams as I think visual memory is very productive) I then would produce exam questions to test knowledge and different approaches to questions