| Magnification calculation | image size/actual size |
| Cell fractionation | - Process where cells are broken up, separating organelles |
| Process required before cell fractionation | Tissue placed in solution which is:
- Cold, to reduce enzyme activity
- Same water potential as tissue, prevent bursting or shrinking of organelles
- Buffered, so pH does not alter the structure of organelles |
| Two stages of cell fractionation | - Homogenation
- Ultracentrifugation |
| Homogenation | - Cells are broken up by a homogeniser (blender)
- Separating organelles from cell
- Resultant fluid, homogenate, is then filtered to remove any debris |
| Ultracentrifugation | - Process by which the fragments in the filtered homogenate are separated in a centrifuge
- Spins at a high speed |
| Ultracentrifugation process | - Tube of filtrate is slowly spun in centrifuge
- Heaviest organelles, the nuclei, are forced to the bottom, forming thin sediment
- The fluid at the top, supernatant, is removed, leaving sediment
- Supernatant transferred to another tube and faster in centrifuge
- The heaviest organelles, mitochondria, are forced to the bottom
- Process continued to separate more organelles |
