Glycolysis takes place in the cytoplasm of your cells. It takes a glucose molecule and splits in half into 2 pyruvic acids. It also produces 2 ATP by adding a phosphate group to a ADP, and NADH by adding electrons to NAD+. After glycolysis comes the second major stage: Krebs Cycle. It takes place in the mitochondria, and during the cycle the pyruvic acids are completely broken down. The energy that's left is stored into NADH or FADH2 molecules or produced into 2 molecules of ATP. Water is a by-product of glycolysis and Carbon dioxide is a by-product of the Krebs Cycle.
Yeah coach. I just passed out for a minute. I haven't eaten anything all day.
Well, it looks like you need more energy. Have you heard of cellular respiration?
I know, coach. And no, I haven't.
Cellular Respiration is about how we get our energy from food, particularly sugar. When we eat food, our body breaks down the sugars into glucose, and then this glucose is used to start the first major stage of cellular respiration: Glycolysis.
The last major stage is the electron transport chain. After the Krebs Cycle, the NADH molecules donate their electrons to the electron transport chain. The electrons are passed through a series of proteins, and then at the end an oxygen molecule accepts them and bonds with 2 hydrogen ions to form water. As a result of this process, energy is produced to move hydrogen ions through the inner mitochondrial membrane and the ATP synthase, which produces most of the ATP we use for energy - about 28 ATP!
So there you go. That's how your body gets the energy that it needs so you can practice without passing out. You need to make sure you eat enough in the future.
Thanks coach, that's very cool, can I go get food now?