In this video, we're going to introduce energy coupling. Energy coupling is essentially when energy released by an exergonic reaction is used to power or drive an endergonic reaction that requires an energy input. Recall from our last lesson video that ATP hydrolysis is a reaction that is an exergonic reaction. ATP hydrolysis releases energy into the environment. ATP hydrolysis is usually what's going to be coupled to endergonic reactions because the released energy from ATP hydrolysis is used to provide the energy input that those endergonic reactions need to proceed.
Let's take a look at our image down below to get a better feel for energy coupling. Notice on the left-hand side, we're showing you this pizza, because a lot of the energy that we get is from the foods that we end up eating. When we eat pizza, the pizza is going to have all different kinds of molecules in it. It's going to have carbohydrates, proteins, lipids, and more. These molecules in the foods that we eat end up providing energy for our bodies.
Our bodies are going to perform exergonic reactions to essentially break down the foods. Here, we’re showing you the reaction for exergonic reactions. They start with large food molecules and break them down into smaller components, ultimately allowing for converting the energy that's in food into chemical energy in the form of ATP. This energy is going to be used to make ATP. Once ATP is made, then the cell can perform ATP hydrolysis.
In this box, you can see the reactants that are needed for ATP hydrolysis to occur. They're going to need ATP and water. ATP hydrolysis is going to be an exergonic reaction. When ATP is hydrolyzed, it is going to release a lot of energy, as we can see here being released, and also, it's going to end up creating a phosphate group as well as ADP. But this energy that is released is really important and this is where the energy coupling comes into play because ATP hydrolysis is an exergonic reaction that releases energy, and this energy is going to be used directly to provide the energy input that's needed for an endergonic reaction, like what you see here.
Using smaller molecules to build larger molecules and also using ATP, the energy released by ATP in order to create kinetic energy, such as when you're riding your bicycle, the energy that's essentially being used is coming from ATP hydrolysis. ATP hydrolysis is going to create ADP and a phosphate group, and these are really the reactants needed for ATP formation or ATP production. You can see that ATP production, the energy that's going to be added into ADP, is going to come directly from the energy in foods that we eat. Ultimately here, what you can see is that with energy coupling, the movements that we have, the kinetic energy that we need to ride a bike, is ultimately going to be derived directly by ATP hydrolysis. ATP hydrolysis has ATP whose energy comes directly from the foods that we eat, breaking down the foods that we eat.
Ultimately, it's the foods that we eat that can be traced to providing the energy for our movements and muscle contractions. Here, exergonic reactions are used to power endergonic reactions, and this is the idea of energy coupling. This here concludes our introduction to energy coupling, and we'll be able to get some practice applying these concepts as we move forward in our course. So I'll see you all in our next video.
