ELECTRON TRANSPORT AND OXIDATIVE PHOSPHORYLATION. GLYCOLYSIS. KREBS CYCLE. NADH. FADH2. NADH. NADH. Electron transport chain... Glucose. Pyruvate. Krebs. Cycle. CO2. H2O. Figure: 6.3. Caption: Cellular respiration consists of three component processes: glycolysis, the Krebs cycle, and electron transport combined with oxidative phosphorylation. Each component produces at least some ATP. Because the three components are connected, cellular respiration is an integrated metabolic pathway. Glycolysis and the Krebs cycle are connected by pyruvate; glycolysis and the Krebs cycle are connected to electron transport chains by NADH and FADH2. CO2. ATP. ATP. ATP. Energy/electrons are transferred from glucose to convert NAD+ to NADH, which is used in the ETC to make ATP.