1. Cellular Respiration Chapter 7 Table of Contents Section 1 Glycolysis and Fermentation Section 2 Aerobic Respiration

2. Section 1 Glycolysis and Fermentation Chapter 7 Objectives Identify the two major steps of cellular respiration. Describe the major events in glycolysis. Compare lactic acid fermentation with alcoholic fermentation. Calculate the efficiency of glycolysis.

3. Chapter 7 Harvesting Chemical Energy Cellular respiration is the process by which cells break down organic compounds to produce ATP. Both autotrophs and heterotrophs use cellular respiration to make CO 2 and water from organic compounds and O 2. products of photosynthesis are reactants in cellular respiration. Cellular respiration can be divided into two stages: glycolysis and aerobic respiration. Section 1 Glycolysis and Fermentation

4. Chapter 7 Photosynthesis-Cellular Respiration Cycle Section 1 Glycolysis and Fermentation

5. Chapter 7 Glycolysis Section 1 Glycolysis and Fermentation

6. Chapter 7 Glycolysis first step both of aerobic and anaerobic respiration Takes place in the cytoplasm During glycolysis, one six-carbon glucose molecule is broken down into 2 pyruvic acid molecules (2 carbons each) A net yield of two ATP molecules is produced for every molecule of glucose that undergoes glycolysis. Section 1 Glycolysis and Fermentation

7. Chapter 7 Glycolysis Takes place in the cytoplasm 1)2 phosphates from ATP attach to glucose to form new 6 carbon compound 2)Unstable compound splits into two 3 carbon compounds (G3P) 3)Phosphate group added to G3P, hydrogen removed by NAD+ to make NADH 4)Phosphate bonds are broken & 2 ATP are produced along with 2 pyruvic acid and 2 NADH Section 1 Glycolysis and Fermentation

9. Chapter 7 Anaerobic Cell Respiration Oxygen not required or not present Takes place in the cytoplasm Glycolysis is the first step Section 1 Glycolysis and Fermentation

10. Chapter 7 Fermentation (Two Types) Lactic Acid Fermentation –In lactic acid fermentation, an enzyme converts pyruvic acid into another three-carbon compound, called lactic acid; NAD+ is produced (used for glycolysis) Alcoholic Fermentation –In alcoholic fermentation, pyruvic acid is converted into ethyl alcohol, NAD+ and CO2 are produced Section 1 Glycolysis and Fermentation

11. Chapter 7 Two Types of Fermentation Section 1 Glycolysis and Fermentation

12. Chapter 7 Objectives Relate aerobic respiration to the structure of a mitochondrion. Summarize the events of the Krebs cycle. Summarize the events of the electron transport chain and chemiosmosis. Calculate the efficiency of aerobic respiration. Contrast the roles of glycolysis and aerobic respiration in cellular respiration. Section 2 Aerobic Respiration

13. Chapter 7 Overview of Aerobic Respiration In eukaryotic cells, the processes of aerobic respiration occur in the mitochondria. Aerobic respiration only occurs if oxygen is present in the cell. The Krebs cycle occurs in the mitochondrial matrix. The electron transport chain is located in the inner membrane.

14. Section 2 Aerobic Respiration Chapter 7 The Krebs Cycle In the mitochondrial matrix, pyruvic acid produced in glycolysis reacts with coenzyme A to form acetyl CoA. Then, acetyl CoA enters the Krebs cycle. 1. Two C acetyl CoA combines with oxaloacetic acid to produce citric acid (6 C) while regenerating coenzyme A 2. Citric acid releases CO2 & H atom w/ electron and forms a 5 C compound. H and electron transferred to NAD+, reducing it to NADH. 3. 5 C compound releases CO2 & H atom w/ electron and forms a 4 C compound. NADH and ATP produced. 4. Another 4 C compound produced by removing H+, FADH2 is produced. H+ released to regenerate oxaloacetic acid to keep the Krebs cycle going, NADH also produced. Overall Production: 6 NADH, 4 CO2, 2 ATP, 2 FADH2

15. Section 2 Aerobic Respiration Chapter 7 Electron Transport Chain and Chemiosmosis High-energy electrons in hydrogen atoms from NADH and FADH 2 are passed from molecule to molecule in the electron transport chain along the inner mitochondrial membrane.

16. Section 2 Aerobic Respiration Chapter 7 Electron Transport Chain and Chemiosmosis, continued Protons (hydrogen ions, H + ) are also given up by NADH and FADH 2. As the electrons move through the electron transport chain, they lose energy. This energy is used to pump protons from the matrix into the space between the inner and outer mitochondrial membranes. The resulting high concentration of protons creates a concentration gradient of protons and a charge gradient across the inner membrane.

17. Section 2 Aerobic Respiration Chapter 7 Electron Transport Chain and Chemiosmosis, continued As protons move through ATP synthase and down their concentration and electrical gradients, ATP is produced. Oxygen combines with the electrons and protons to form water.

18. Section 2 Aerobic Respiration Chapter 7 Electron Transport Chain and Chemiosmosis, continued The Importance of Oxygen –ATP can be synthesized by chemiosmosis only if electrons continue to move along the electron transport chain. –By accepting electrons from the last molecule in the electron transport chain, oxygen allows additional electrons to pass along the chain. –As a result, ATP can continue to be made through chemiosmosis.

19. Section 2 Aerobic Respiration Chapter 7 Efficiency of Cellular Respiration Cellular respiration can produce up to 38 ATP molecules from the oxidation of a single molecule of glucose. Most eukaryotic cells produce about 36 ATP molecules per molecule of glucose.

20. Section 2 Aerobic Respiration Chapter 7 A Summary of Cellular Respiration Another Role of Cellular Respiration –Providing cells with ATP is not the only important function of cellular respiration. –Molecules formed at different steps in glycolysis and the Krebs cycle are often used by cells to make compounds that are missing in food.

21. Chapter 7 Summary of Cellular Respiration Section 2 Aerobic Respiration

22. Chapter 7 Cellular Respiration Versus Fermentation Section 1 Glycolysis and Fermentation