by Claire Greene Whitfield
Fun Rating: 5/5
Difficulty Rating: 1/5
What is the general purpose?
Centrifugation is a widely used technique for separating different components of samples – think about how the ‘snow’ inside a snowglobe settles at the bottom after a long period of time.
By spinning the sample (or snowglobe) around at high speeds, we can separate the ‘snow’ layer from the liquid layer more quickly. We can use this same logic to sort the contents of biological samples! |
| Figure 1. The different layers of a snowglobe with and without a centrifuge step. Image created by the author in BioRender |
Why do we use it?
Using centrifugation to separate your samples saves time, energy, and even money. Although the centrifuge itself can be expensive, it can last a long time and is used frequently for a variety of protocols, such as DNA extraction, mammalian cell culture, and cellular fractionation. A centrifuge is considered essential in most biological research labs that study molecular biology, genetics, microbiology and immunology!
How does it work?
A centrifuge works by spinning your samples in a circle really fast so that the heaviest (most dense) components are pulled to the bottom of the tube and the lighter (least dense) components form layers on top.
| Figure 2. Centrifuges come in many shapes and sizes, but they all work the same way to separate samples into layers. Top image created by the author in BioRender; bottom image modified from glanlab.com |
The high-speed spinning motion creates what are called ‘centrifugal forces’ – or rotational forces that send particles away from the rotating center. This technique is helpful in the laboratory for separating DNA from proteins, fats, and other cell components, as in DNA extraction.
Have you ever heard a family member or friend talk about having their blood tested? Centrifugation can also be used to sort different types of blood cells from patient samples in hospitals and clinics. If you ever wondered how hospital staff process the sample for testing, centrifugation is the answer! Once centrifuged, the blood separates into several layers: red blood cells, white blood cells (which are essential to the immune system!), platelets, and plasma. Click here to learn more about the different components of blood and how important it is to the body!
| Figure 3. Centrifugation is used in hospitals and clinics to process blood samples for analysis. Image source: https://pathologytestsexplained.org.au/ptests.php?q=Full+blood+count |
Insider tip: Scientists will sometimes say “spin down” instead of centrifuge!
