All humans need to eat. We eat to get glucose. Glucose is a simple form of sugar. However Glucose is not like the type of sugar in candy.
Your burger Ma'am
Little do we know that when we are eating and digesting, the cells in our bodies are working so hard to provide energy to the rest of the cell. This type of energy is called ATP. This process is called cellular respiration.
To start cellular respiration you need oxygen and glucose. You eat the glucose and you breathe in the oxygen. The oxygen diffuses through the cell membrane and makes it's way to the mitochondria. But the glucose is too big to fit through the cell membrane. So it goes through something called the protein channels!
The triangles are glucose molecules and the ovals are oxygen.
They oxygen and glucose find their way to the mitochondria which turns them into ATP. During this process water and carbon dioxide molecules are also released into the cell.
The ATP float around bumping into other particles. When this happens one of the phosphates falls off. Then it's name changes to ADP! Then the ADP goes back to the mitochondria to grab another one.
Huh! Ok, bye!
The ADP makes it's way back to the mitochondria, still bumping into things but having no effect. At the mitochondria it picks up a third phosphate, becomes an ATP again and begins its journey anew!