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It's pretty simple. A reaction occurs that releases energy (like ATP losing a phosphate to become ADP + Pi). If this is uncoupled, the energy will merely turn into heat. If it is coupled, then it can be used to fuel some other process. For instance, if you couple the ATP -> ADP reaction to a certain protein, the energy can be used to modify the shape of that ...

A coupled biochemical reaction is one where the free energy of a thermodynamically favourable reaction (such as the hydrolysis of ATP) is used to 'drive' a thermodynamically unfavourable one, by coupling or 'mechanistically joining' the two reactions. To put it another way, two (or more) reactions may be combined by an enzyme (for example) such that a ...

Since there seems to be several distinct sub-topics in your question, I will answer them one-by-one: 1). There are a variety of mechanisms that allow endothermic animals to maintain thermal homeostasis in a cold environment. The main ones are: a). The shivering response: When the core body temperature of a endotherm drops below a critical value (36.8C in ...

Measuring the work done by a biological system seems pretty impossible. Imagine how many different ways one cell of your body uses energy (ATP). You can't really measure all the work done by every cell on a macro scale. Metabolic efficiency has been defined as... "health". That seems just a little ambiguous. That's why we use things like averages to ...

From pure biophysical viewpoint the question "Why does water buffer sudden temperature changes?" can be answered in the following way: Water has relatively high specific heat capacity. This is the measure of the energy required to raise the temperature of one kilogram of a substance by one kelvin without a change of state occurring. "Relatively high" ...

The phosphoryl transfer potential is one way to think about the free energy available to do useful work when ATP is hydrolysed. As you can see from the free energy equation below, a positive change in entropy will help to decrease (i.e. make more negative) the free energy change. This is why an endothermic reaction can still occur spontaneously if the ...