How Do Human Cells Calculate and Utilize ATP?

[deenuh20]

Biochemistry--Double check my answers please

Homework Statement

Part 1: 32 kJ/mol of free energy is needed to synthesize ATP from ADP and Pi when all reactants are at standard conditions (1M). In a human hepatocyte (liver cell), concentrations are far less. Calculate the actual free energy of the synthesis of ATP when concentrations are [ATP]=3.5 mM, [ADP]=1.50mM and [Pi]=5.0mM.

Part 2: A 150 lb human adult requires ~2000 kcal of caloric intake per day. Assuming that efficiency of metabolism is only 50%, calculate the mass of ATP used by a human adult in 24 hours. Use number obtained in #4 for your calculation. (Note: 1 calorie = 4.184 Joules)

Homework Equations

delta G= standard G + RT ln (products/reactants)

The Attempt at a Solution

For part 1, I did:

Delta G= 32,000 J/mol + (8.315 J/(mol*K))(298K) ln (ATP/(ADP*Pi))
Delta G= 32,000 J/mol + (2477.87 J/mol) ln (3.5x10^-3)/(1.5x10^-3 x 5x10^-3)
Delta G= 32,000 J/mol + (2477.87 J/mol) ln (466.667)
Delta G= 47228 J/mol

For part 2, I did:

[(0.5)*(2000 x 10^3 cal)*(4.184 J)*(503 g/mol ATP)] all divided by 47228 J and got 44561.5 g ATP


Thanks for your help!

 

[TeethWhitener]

This all looks fine. I want to point out that, yes, in fact your body does use on the order of 40-50 kg of ATP per day, due to the massive amount of recycling that goes on in your cells.