How many atoms are in each cell?

[jakebarrington]

How many atoms are there in the average human cell? Including all parts of the cell (lipid bilayer, nucleus, ribosomes, etc.)

[timo]

Assume a thousand times the density of a gas (NA atoms in 23 litres, if I remember correctly) and scale it down to the volume of a human cell. Should give a rough estimate.

[swansont]

Assume a thousand times the density of a gas (NA atoms in 23 litres, if I remember correctly) and scale it down to the volume of a human cell. Should give a rough estimate.

 

Density of water would work, as well, as a justification. Organisms tend to be neutrally buoyant, to a first-order approximation. Both give about a gram per cm^3. (and yes, that number is approximately right — it's 22.4 liters per mole at STP)

[timo]

As a matter of fact by "1000 times the mass of gas" I mean a typical fluid. Of course looking up the density or approximately knowig it is more accurate than my guess. I like the argument for chosing water as a specific fluid.