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calculating the molar ration - (Jun/03/2005 )

hi, i am new here. I am a molecular biology student. I was doing extra problems for my exam on tuesday and was wondering if some could help me.

i have to calcuate teh lipid mole fraction of cholesterol in plamsa membrane.

this is what i am thinking, teh average molecuar weight of protien is 800g/mol and 400g/mol for choesterol.
i have teh cholesterol percentage in plasma membrane as 0.13 mg/mg of protein.

therefore I think
that for ever 1 mg of protein there is .13 mg of cholesterol
then 400g/mol / .00013 g = will give you moles of cholesterol??? is this right????



sum up informations:
protein molecular weight : 800g/mol cholesterol molecular weight : 400g/mol
mass ratio is 0.13 mg for 1mg of protein

0.13 mg of cholesterol is (0.00013/400) 0.325┬Ámol
1mg of protein is (0.001/800) 1.25┬Ámol

hence the molar ratio is cholest / protein : 0.325/1.25
that is 0.26 mol of cholesterol for 1 mol of protein...