Metabolic Pathways and Energy Production

1. Metabolic Pathways and Energy Production Metabolism and ATP Energy Important Coenzymes Glycolysis

2. Metabolism All the chemical reactions that occur in the cells of our bodies. Catabolic reactions • Break down large molecules • Provide energy for ATP Anabolic reactions • Use small molecules to build large ones • Require energy catabolic anabolic

3. Cell Structure Typical animal cell • Nucleus • Chromosomes in the nucleus contain genetic material • Cytoplasm is material between nucleus and cell membrane • Mitochondria are where energy-producing reactions occur

4. ATP • Energy is released as food is oxidized • Used to form ATP from ADP and Pi ADP + Pi + Energy ATP • In cells, energy is provided by the hydrolysis of ATP ATP ADP + Pi + Energy

5. Structure of ATP

6. Digestion of Foods Digestion is the first step of catabolism • Carbohydratesglucose, fructose, galactose • Proteins amino acids • Lipids glycerol fatty acids

7. Coenzymes • Substances that connect metabolic pathways • In reduction, coenzymes accept H atoms • In oxidation, coenzymes remove H atoms FAD (flavin adenine dinucleotide) FAD+ -CH2-CH2- FADH2 + -CH=CH- NAD+ (nicotinamide adenine dinucleotide) NAD++ -CH-OH NADH + H+ + -C=O

8. Glycolysis: Oxidation of Glucose 2ATP 2 NAD+ 2ADP 2NADH + 2H+ 4 ADP 4 ATP Glucose two Glyceraldehyde-3-PO4 two Pyruvate

9. Glycolysis: Oxidation of Glucose

10. Glycolysis: Oxidation of Glucose 2 NAD+ 2 NADH + 2 H+

11. Glycolysis: Oxidation of Glucose Glycolysis generates 2 ATP molecules and 2 NADH + 2 H+ Two ATP used in adding phosphate groups to glucose and fructose-6-phosphate (- 2 ATP) Four ATP generated in direct transfer to ADP by two 3-C molecules (+ 4 ATP) Glucose + 2 ADP + 2 Pi + 2 NAD+ 2pyruvate + 2 ATP + 2 NADH + 2 H+

12. Pathways for Pyruvate Aerobic conditions O || CH3–C –COO- + NAD+ + CoA pyruvate O || CH3–C –CoA + CO2 + NADH + H+ acetyl CoA

13. Pathways for Pyruvate Anaerobic conditions (No O2 available) Reduce to lactate to replenish NAD+ for glycolysis O OH || | CH3–C –COO- + NADH + H+ CH3–CH –COO- + NAD+ pyruvate lactate enzyme: lactate dehydrogenase

14. Lactate in Muscles • Strenuous exercise leads to anaerobic conditions • Oxygen in muscles is depleted • Lactate builds up as glycolysis continues • Muscles tire and become painful • Breathing rate increases • Rest repays oxygen debt • Lactate re-forms pyruvate in liver

15. Learning Check M1 Match the following with the terms below: (1) Catabolic reactions (2) Coenzymes (3) Glycolysis (4) Lactate A. Produced during anaerobic conditions B. Reactions that convert glucose to pyruvate C. Metabolic reactions that break down large molecules to smaller molecules + energy D. Substances that remove or add H atoms in oxidation and reduction reactions

16. Solution M1 Match the following with the terms below: (1) Catabolic reactions (2) Coenzymes • Glycolysis (4) Lactate A. 4 Produced during anaerobic conditions B. 3 Reactions that convert glucose to pyruvate C. 1 Metabolic reactions that break down large molecules to smaller molecules + energy D. 2 Substances that remove or add H atoms in oxidation and reduction reactions