The Weight of a Cell
6 days ago
- #cell biology
- #scientific history
- #measurement techniques
- A single yeast cell weighs about 100 picograms, and an E. coli bacterium weighs about one picogram.
- Early methods to measure cell weight used Stokes' law, requiring only a microscope, sugar water, and a camera.
- Stokes' law calculates drag force on a sphere moving through a liquid, allowing mass determination if radius, velocity, and fluid properties are known.
- In 1953, researchers measured yeast cell weight by filming their descent in sugar water and applying Stokes' law, yielding an average of 79 picograms.
- Modern devices like the suspended microchannel resonator measure cell mass with femtogram precision by detecting frequency shifts as cells pass through a vibrating beam.
- E. coli cells weigh about 0.55 picograms on average, with growth rates varying by size.
- Historical experiments, like Lord Rayleigh's calculation of oil molecule size, demonstrate how simple tools and mathematics can yield precise biological measurements.