This is elderberry wine on its way to completion. I added sugar to the elderberries and then added yeast. Yeast is a living things, a single-celled type of fungus. Like us it needs to do some form of respiration to turn its food into useable energy. Unlike us, it can only do a type of anaerobic respiration - respiration without oxygen. For yeast, the full reaction is called FERMENTATION.
However, it does involve the GLYCOLYSIS reaction in the CYTOPLASM of the cell that we have studied. Here it is...
The energy supply to start the reaction comes from ATP. This contains 3 phosphate groups but bonds are broken as it loses a phosphate group to become ADP. Breaking these bonds releases some energy and this energy is used to turn glucose into glucose phosphate, Glucose has SIX carbon atoms as does glucose phosphate. But then glucose phosphate splits into two TP molecules. Each TP molecule contains only THREE carbon atoms.
Each TP molecule now needs to turn into pyruvate. To do so, it needs to lose a hydrogen and a phosphate. Bonds are broken so the TP loses energy. That energy has to go somewhere. It is used up turning ADP back into ATP. And the NAD+ mops up the spare hydrogen atom.
We can get away with saying that ATP is high energy and ADP is low energy. Going from ATP to ADP releases energy. Going from ADP to ATP needs energy. Overall glycolysis makes more ATP than it uses up. So the cell ends up with more high energy ATP than it had at the start. So we say that the cell has gained energy from the breaking up of glucose into two pyruvate molecules.
