In this video, we're going to talk about the ATP cycle. So let's begin with a molecule called ADP. ADP is adenosine diphosphate, and it has two phosphate groups. Now we're going to convert this to ATP, adenosine triphosphate, which has three phosphate groups. So to show that visually, here's what we can do.
I'm going to put A for adenosine. and the two phosphate groups there. And ATP has three phosphate groups.
Now in order to make ATP from ADP, we need an inorganic phosphate. Now ATP has more energy than ADP. So in order to go from ADP to ATP, we need to put energy in. to this process.
So because we're putting energy in, this is going to be an endergonic reaction or an endergonic process. Anytime energy is absorbed in a reaction, you have an endergonic reaction. Now let's talk about the other part of the cycle, converting ATP to ADP. In this case, we need to lose a phosphate group. So a phosphate group is going to come out of the cycle.
Now, on the first half, or on the left side, we put in energy to make ATP. So in this case, energy is going to come out. The right side is basically the reverse of the left side.
So we're going from a molecule that has more energy to a molecule that has less energy. So thus energy will be released. Now because we're releasing energy, that process is known as an exergonic process. Anytime energy is released in a reaction, it's an exergonic reaction. Now there's one more thing that we need, and that is water.
To convert ATP to ADP, we need water. And so this is a hydrolysis reaction. We need to use water to break one of the phosphate bonds. Now, if the right side is a hydrolysis reaction, the left side must be a dehydration synthesis reaction.
So water is released on the left side. So that is the ATP cycle. That's how ADP converts into ATP.
and vice versa. Now let's summarize the reaction another way. So when we combine ATP with water, we're going to make ADP, adenosine diphosphate, and we're going to release a phosphate group, and we're going to get energy in the process. So that is an example of the hydrolysis reaction.
And as we said before, this is an exergonic reaction since energy is released. Now on the other side, we have ADP reacting with inorganic phosphate, and we need to put in energy to make this work. And we're going to produce ATP, and we're going to release water as a byproduct. So this process is a dehydration synthesis reaction because we're forming a bond and we're releasing water. We're forming a bond between the two phosphate groups.
So because we're putting in energy or because energy is on the left side of the chemical equation, this is an endergonic reaction. We need energy to drive this reaction forward. And so that's the ATP cycle. In order to make ATP, you need to put energy into it. So ATP is a form of short-term energy storage.
But once we convert ATP back into ADP, then that energy that was stored can be released to do useful work, such as powering active transport, or synthesizing molecules, or even driving other endergonic reactions. So ATP is the energy currency of the cell. It's very useful for getting things done and accomplishing many cellular processes. So that's it for this video. Thanks for watching and don't forget to subscribe.