Energy and Metabolism

ID #1660

How does spreading the breakdown of glucose into carbon dioxide and water over multiple reactions harness more energy and prevent dissipation of energy as heat?

Suppose you have a reaction where A gets converted into Z. If that reaction occurs in one step, it releases 100 made up units of energy. Now suppose that a typical endergonic reaction in a cell actually requires 5 units of energy to make it happen. The A -> Z reaction could of course "pay" for one of these reactions, but 95 of your units of energy would be lost as heat. But if A gets converted to B in a reaction that only releases 10 units of energy, then B gets converted to C releasing another 10 units, and so on, then each "smaller" reaction can either be directly coupled with a cellular endergonic reaction, or the energy can be "stored" until later. This leaves the heat loss at a minimum, although it cannot be totally avoided.

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