X-Message-Number: 21319
Date: Sat, 01 Mar 2003 14:07:19 +0100
From: Henri Kluytmans <>
Subject: How many atoms in a Red Cell

Kennita Watson wrote :

>I'm asking this just because I think someone here might
>know off the top of their head:  About how many atoms
>are there in the average red blood cell?  The average
>white blood cell?  Just curious.

Not off the top of my head though, but here we go :

---------------------------------------------------------

For the average Red Blood Cell :

Size 			:	7.82 x 2.58 micron biconcave disk =  ~30-35 micron^3 volume
Density 		:	1100 kg/m3

Let's assume 	:	65% water 20% proteins 12% lipids 3% other
				(from nanomedicine in weight % for typical human cell)

Weights of atoms (not considering isotopes) in amu's :  H=1 C=12 N=14 O=16 

Molecular weight typical protein	:	50,000 amu
Molecular weight typical lipid		:	700 amu
Molecular weight water molecule		:	18 amu

Atomic constitution of these molecules.
I'm guessing lipids and proteins are constituted of about :
30% C, 47% H, 12% O and 11% N atoms. (Im using 25C,40H,10O,10N)

# atoms :

Typical protein 	= ~6650 atoms	(I guess about 5% error in estimate ?)
Typical lipid		= ~95   atoms	""
Water molecule		=  3    atoms

One mole = 6.02 x 10^23 molecules   (weight of 1 mole of H = 1 gram)

=====================

Result for 1 cubic micron of cell volume (weight = 1.1*10^-12 gram) :

1.1*10^-12 *0.65/18 *6.02*10^23 = 2.39 *10^10 molecules = 7.2 *10^10 atoms
"		*0.20/50000  "		= 2.64 *10^6  molecules = 1.8 *10^10 atoms
"		*0.12/700    "		= 1.13 *10^8  molecules = 1.1 *10^10 atoms

Water		:  7.2 * 10^10 atoms
Proteins	:  1.8 * 10^10 atoms 	
Lipids	:  1.1 * 10^10 atoms
Other		:  0.3 * 10^10 atoms  (just a guess)

Total		:  10.4 * 10^10 atoms  for  1 cubic micron of cell volume  (5% error?)
		   ==================	

----------

Volume of Red Cell   = ~ 30-35 micron^3  

Volume of White cell = ~ 1000-4000 micron^3


Cheers,
>Hkl

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