Energy and Metabolism

ID #1034

When talking about spontaneous reactions, my notes say much is lost to heat. Is that heat harnessed into energy, or are our cells somewhat inefficient with catabolic reactions? I mean, is only a fraction of the energy released actually used to power cellular functions?


Cells have two main ways to avoid losing significant energy as heat. No biological system is 100% efficient, so some energy will simply be lost as heat, but the goal becomes to minimize that loss. One strategy is to take a reaction that would release tremendous energy and break it down into smaller steps. Each step releases a smaller amount of energy, and hopefully most of that can be harnessed and stored. The other strategy is to use energy sources, like ATP which we'll learn about, which are not really all that high in energy on the spectrum from highest energy compounds to lowest. This way, if a reaction "costs" a moderate amount of energy to drive, you use a currency which releases an amount of energy approximately equal to what the cost is, minimizing the "change" that you get back from that "transaction."

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