ATP: The energy of the cell
The endgame of cellular respiration is ATP. Adenosine triphosphate is the energy currency of the cell—it’s a high-energy molecule with a carbon backbone attached to three phosphate groups (hence triphosphate). In these phosphate bonds, it’s able to store energy.
When one of these bonds is broken, one phosphate group will be removed from ATP and stored energy will be released. But the molecule will no longer be adenosine triphosphate—it becomes adenosine diphosphate, or ADP.
We can also go the other way and create ATP from ADP by adding a phosphate group back on (phosphate groups are often denoted as “Pi”), but this takes a bit of force to do. This process is called phosphorylation.
It’s important to know that ATP is what we want to get out of cellular respiration. Cells are provided with energy in the form of glucose, and they want to break it down into energy it can use: ATP. It’s literally a process of currency conversion—it’s a bit more complicated than changing from pounds to dollars, but it’s a whole lot cooler, too, because each one of your cells carries out these complex processes every second of every day.
Let’s check out the first stage: glycolysis.
Images sourced from Wikimedia Commons
Further resources: Khan Academy: ATP