High doses of caffeine interffere with the DNA replication checkpoint mechanism

Question

High doses of caffeine interffere with the DNA replication checkpoint mechanism in mammalian cells. Why then do you suppose the U.S. Surgeon General has not yet issued a warning to heavy coffee and cola drinkers? (To answer this question, let's assume that a 150 ml cup of coffee contains 100 mg of caffeine (196 g/mol), and for the sake of the calculation, that you cannot measurably metabolize or excrete caffeine (Which is not true) in the period of one day once you ingest it.How many cups of coffee would you have to drink in that day to reach the dose (10mM) required to interfere with the DNA replication checkpoint mechanism? (A typical adult contains about 40 liters of water in total body fluid; we'll assume that you can excrete the water that you ingest, thus the total body fluid volume will remain constant at 40 liters))

Explanation / Answer

10Mm = 10millimoles/liter = .01moles/liter (M), minimum concentration to interfere with checkpoints.

.01moles/L= X moles/40L, X=.4moles needed to interfere with checkpoints in a human.

100mg = 1g * (1mol/196g) = .005102moles in one cup of coffee.

150mL=.15L in one cup of coffee.

.005102mol/.15L = .03401M in one cup of coffee.

.4mol=.03401M* X liters

X= 11.7612L needed/.15L in one cup = 78.4 cups of coffee, round to 79.

It is impossible to drink 79 cups of coffee in a day.

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