How it works
This cell fractionation diagram reads left to right. The first view breaks tissue open and spins it once. The second follows the supernatant through spin after spin, with a close-up of what each pellet holds.
Read the full guide
Read the diagram of cell fractionation left to right
Tissue is ground in a homogenizer until its cells break open. The cloudy mixture, the homogenate, goes into a centrifuge. After the spin a pellet lies at the bottom of the tube, and the supernatant is the liquid above it.
Large parts come down first
The supernatant is spun again and again, each time faster or for longer. Nuclei come down first, then mitochondria, then microsomes, then ribosomes. What stays dissolved at the end is the cytosol.
- Spin speeds and times differ from book to book, so the quiz asks only the order.
- Lysate is accepted for homogenate.
Questions and answers
What is cell fractionation?
A way of taking cells apart and separating their organelles, so that each kind can be studied on its own. The cells are broken open, then the mixture is spun in a centrifuge.
What are the steps of cell fractionation?
Homogenization, which breaks the cells open, then differential centrifugation: the mixture is spun, the pellet is kept, and the supernatant is spun again at a greater force or for longer.
Which organelle comes down first in differential centrifugation?
The nucleus. Nuclei are the largest organelles, so they reach the bottom of the tube in the slowest spin. Mitochondria follow, then microsomes, then ribosomes.
What is the difference between a pellet and a supernatant?
The pellet is the packed material at the bottom of the tube after a spin. The supernatant is the liquid left above it.
What are microsomes?
Small closed vesicles that form from broken membranes, such as the endoplasmic reticulum and the cell membrane, when cells are homogenized.