READ THIS!-# of atoms in a human cell?

Alexander Berezin berezin at MCMAIL.CIS.MCMASTER.CA
Fri Nov 10 23:50:07 EST 1995



On 10 Nov 1995 paul.boduch at YALE.EDU wrote:

> On Fri, 10 Nov 1995, Alexander Berezin wrote:
> 
> > On Fri, 10 Nov 1995, Paul Boduch (ES 1997) wrote:
> > 
> > > 	Does anybody know the average number of atoms in a human cell? 
> > > Could please e-mail it to me fast? I know for a fact that there's 10^27 
> > > atoms in an average human body. If you knew the average # of cells, you 
> > > could just divide that into 10^27 to come up with the answer.
> > > 
> > > 
> > 
> > VEIW OF A NON-BIOLOGIST (but knew some chemistry once):
> > You better start with the Avogadro #, chemical composition of a cell
> > (I guess, the average atomic weight is about 12 as we are mostly
> > a mixture of H, O, C amd N) and average size of a cell, which 
> > (again a guess) is about several microns.
> > The answer has nothing to do with the weight of human body
> > and likely about the same for all (animal) biostuff.
> > Alex Berezin  
> Sorry, it's been a while since I've done Avogadro # calculations and I 
> don't have the data on the relative proportions of H, O, C, and N which I 
> believe one would need to do the calculation. There's gotta be somebody 
> out there who knows the average # of cells in a human body, so I don't 
> have to pour through hundreds of bio books to find the answer. Anyone?
> 
> 
All right. Than the answer (estimate) is about 10^12 atoms per cell.
(volume of a cell, say 5 x 5 x 5 microns = 100 cubic microns =
= 10^-16 cubic meters; volume of the average human bidy is 100 liters =
= 0.1 cubic meteres = 10^15 cubic microns; 10^27/10^15 = 10^12 atoms
per cell).
Alex Berezin



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