Explore: Drag each molecule from the MOLECULES pane to the RESPIRATION pane.
Observe: Click Next. Observe what happens in the cytoplasm (the stuff surrounding the mitochondria).
This process is called glycolysis. Two pyruvate (C3H3O3–) molecules are produced in glycolysis. The released energy is used to form a net of two ATP (adenosine triphosphate) molecules. Energy is later released when ATP molecules are broken down.
Observe: Click Next. What happens now?
Observe: Click Next. What happens in the mitochondrion?
Energy from the mitochondrion is also stored in the form of ATP. A net of 30 ATP molecules is produced for every two molecules of pyruvate.
In the mitochondrion, the two molecules of pyruvate undergo a series of reactions known as the Krebs cycle, or citric acid cycle. This cycle breaks down the pyruvate molecules further, releasing more energy in the form of NADH and FADH2. These molecules then enter the electron transport chain, where they donate their electrons to a series of protein complexes. This process generates a proton gradient across the inner membrane of the mitochondrion, which is used to produce ATP through a process called oxidative phosphorylation. Overall, the oxidation of the pyruvate molecules in the mitochondrion produces a net of 30 ATP molecules.
