Glycolysis: 2 ATPs are used, each of the 6 carbon atoms in a glucose molecule is broken into two molecules of the three-carbon compound pyruvate and 4 ATP produced and 2 NAD+ are reduced to NADH
Pyruvate is processed to release one molecule of CO2 and the remaining two carbons are used to form acetyl CoA and NAD+ is reduced to NADH
Citric acid cycle: the energy released from the oxidation of acetyl CoA is used to produce three molecules of CO2, two NADH, one FADH, one GTP (liver cells) or ATP (muscle cells), the cycle turns twice for each molecule of glucose processed because glycolysis produces two molecules of pyruvate
The electrons from NADH AND FADH2 are oxidized to NAD+ and FAD, and the electrons are transferred to oxygen which is reduced to form water
