University:
University of North Georgia
Course:
BIOL 3240K | Cell Biology
Academic year:

2022
Views:

200

Pages:

10
Author:

ilikemyicons0y5

Concept 9.1 Cells Harvest Chemical Energy from Glucose Oxidation In glucose metabolism, glucose is the reducing agent and O2 is the oxidizing agent. The more reduced a molecule is, the more energy it has. In a redox reaction, some energy is transferred from the reducing agent (glucose) to the reduced product. (7) Figure 9.3 Oxidation, Reduction, and Energy Concept 9.1 Cells Harvest Chemical Energy from Glucose Oxidation Transfer of electrons is often associated with transfer of hydrogen ions: H  H  e When a molecule loses H atoms it becomes oxidized. (8) Concept 9.1 Cells Harvest Chemical Energy from Glucose Oxidation Coenzyme NAD+ is a key electron carrier in redox reactions. Reduction: NAD  H  2e   NADH Oxidation: NADH  H  ½ O2  NAD   H2O exergonic: G =  52.4 kcal/mol (9) Figure 9.4 NAD+/NADH Is an Electron Carrier in Redox Reactions Concept 9.1 Cells Harvest Chemical Energy from Glucose Oxidation In aerobic conditions, O2 is available as the final electron acceptor; four metabolic pathways operate. In anaerobic conditions, the pyruvate produced by glycolysis is metabolized by fermentation. (10) Figure 9.5 Energy-Yielding Metabolic Pathways Concept 9.2 In the Presence of Oxygen, Glucose Is Fully Oxidized (1) Glycolysis • Takes place in the cytoplasm • Converts glucose into 2 molecules of pyruvate • Produces 2 ATP and 2 NADH • Occurs in 10 steps Concept 9.2 In the Presence of Oxygen, Glucose Is Fully Oxidized (2) Steps 1–5 require ATP (energy-investing reactions). Steps 6–10 yield NADH and ATP (energyharvesting reactions). Figure 9.6 Glycolysis Converts Glucose into Pyruvate (Part 1)