High School

Combustion of glucose ([tex]C_6H_{12}O_6[/tex]) is the main source of energy for animal cells:

[tex]C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O[/tex]
ΔG = -2872 kJ (at 37 °C)

This energy is generally stored as ATP (adenosine triphosphate) molecules, which can release it when convenient by hydrolysis into ADP (adenosine diphosphate) molecules and a phosphate anion (P).

[tex]ATP (aq) \rightarrow ADP (aq) + P (aq)[/tex]
ΔG = -35 to -70 kJ

Suppose under certain conditions hydrolysis of ATP actually releases -66.9 kJ/mol. Calculate the maximum number of ATPs that could be created from ADPs and P by the combustion of a molecule of glucose.

Answer :

To calculate the maximum number of ATP molecules that can be produced from the combustion of a single glucose molecule, we'll follow these steps:

  1. Understand the Energetics of the Reaction:

    • The combustion of glucose releases a free energy change (ΔG) of -2872 kJ/mol.
    • Hydrolysis of ATP releases free energy ranging from -35 to -70 kJ/mol. Under the given condition, ATP hydrolysis releases -66.9 kJ/mol.

  2. Calculate Maximum ATP Production:

    • If ATP hydrolysis releases 66.9 kJ/mol, the same amount of energy is required to synthesize one ATP molecule from ADP and P.
    • The maximum number of ATP molecules produced can be calculated by dividing the total energy released in glucose combustion by the energy required to form one ATP:

    [tex]\text{Maximum ATPs} = \frac{-2872 \text{ kJ/mol}}{-66.9 \text{ kJ/mol}} = 42.93[/tex]

  3. Result Rounding:

    • Since we can't produce a fraction of a molecule, we round down to the nearest whole number. Therefore, a maximum of 42 ATP molecules can be synthesized from one molecule of glucose under these conditions.

This calculation assumes 100% efficiency of energy conversion, which doesn't occur in real cells due to various inefficiencies and losses. However, this provides a theoretical maximum under ideal conditions.

Other Questions