Cellular Respiration

1. Cellular Respiration

2. Cellular Respiration • Cellular respiration releases chemical energy from sugars and other carbon-based molecules to make ATP. • It is an aerobic process. • needs oxygen to take place.

3. Cellular Respiration • Cell respiration takes place in the mitochondria. • Foods are broken down into small molecules like glucose. • Glucose is broken down during glycolysis.

4. Glycolysis • Glycolysis • Takes place BEFORE cell respiration. • Splitsthe glucose molecule into two three-carbon molecules and makes two molecules of ATP. • It takes place in the cytoplasm of the cell. • It is an anaerobicprocess. • Does NOT require oxygen to take place.

5. Glycolysis 1. Two ATP molecules are used to energize a glucose molecule. • The glucose is then split into two three-carbon molecules. 2. Energized electrons from the three-carbon molecules are transferred to molecules of NAD+. • This makes NADH. (this is an enzyme that helps energy production) • A series of reactions convert the three-carbon molecules into pyruvate. (used in cellular respiration) • 4 ATP molecules are made.

6. Krebs Cycle • The first part of cellular respiration. • Sometimes called the citric-acid cycle. • Producesmolecules that carry energy to the second part of cellular respiration. (NADH and FADH2) • Takes place in the interior space (matrix) of the mitochondria.

7. Krebs Cycle 1. Pyruvate broken down. • Pyruvate is split into a two-carbon molecule and carbon dioxide (given off as waste). • The two-carbon molecule donates high energy electrons to NAD+, forming a molecule of NADH. • This will move to the electron transport chain. 2. Coenzyme A • Bonds to the two-carbon molecule made by the breakdown of pyruvate.

8. Krebs Cycle 3. Citric acid formed. • The two-carbon molecule binds to a four-carbon molecule to form citric acid. • Coenzyme A returns to step 2. 4. Citric acid broken down. • The citric acid molecule is broken down by an enzyme, and a five-carbon molecule is formed. • A molecule of NADH is made and moves out of the Krebs cycle. • A molecule of carbon dioxide is given off as waste.

9. Krebs Cycle • 5. Five-carbon molecule broken down. • A four-carbon molecule, a molecule of NADH, and a molecule of ATP are formed. • NADH leaves the Krebs Cycle. • Carbon dioxide is given off as waste. • 6. Four-carbon molecule rearranged. • Enzymes rearrange the four-carbon molecule, releasing high-energy electrons. • NADH and FADH2 (another enzyme/electron carrier) are made. • They leave the Krebs cycle and the four-carbon molecule remains.

10. Krebs Cycle Products • The Krebs cycle will break down TWO pyruvate molecules at the same time. • Products: • 6 carbon dioxide molecules. • 2 molecules of ATP • 4 molecules of NADH • Will go to the electron transport chain. • 2 molecules of FADH2 • Will go to the electron transport chain.

11. Electron Transport Chain • Second part of cellular respiration. • Energy from the Krebs cycle (NADH and FADH2) is transferred to a chain of proteins in the inner membrane of the mitochondrion. • A large number of ATP molecules are made. • Oxygen is used to make water molecules. • Water and heat are given off as a waste

12. Electron Transport Chain 1. Electrons removed. • Proteins inside the mitochondrion take high-energy electrons from NADH and FADH2. • Two molecules of NADH and one of FADH2 are used. 2. Hydrogen ions transported. • Hydrogen ions are built up along the inner mitochondrial membrane using energy from the electrons.

13. Electron Transport Chain • 3. ATP produced. • The hydrogen pumps through a protein channel in the mitochondrial membrane with ATP synthase. • ATP synthase adds phosphate groups to ADP to make ATP molecules. • Each pair of electrons (hydrogen) that passes through results in an average of 3 ATP molecules made. • 4. Water formed. • Oxygen enters the cycle and picks up extraneous hydrogen, forming water. • This is given off as a waste.

14. Electron Transport Chain

15. Electron Transport Chain Products • For EACH molecule of glucose the ETC can make: • Up to 34 molecules of ATP

16. Cellular Respiration Products • Up to 38 ATP are made from the breakdown of ONE glucose molecule. • 2 ATP from glycolysis • 36-34 ATP from cellular respiration (Krebs Cycle and Electron Transport Chain) • Other products include carbon dioxide and water. • The equation for cellular respiration is: • C6H12O6 + 6O2 6CO2 + 6H2O

17. Fermentation • Fermentation is an anaerobic process that takes place when there is less oxygen in the body (i.e. during strenuous activity) • Fermentation does NOT make ATP, but it allows glycolysis to continue. • Glycolysis needs NAD+ to pick up electrons when it splits glucose into pyruvate. • Fermentation removed electrons from NADH molecules and recycles NAD+ molecules for glycolysis.

18. Lactic Acid Fermentation in Animals 1. Pyruvate and NADH from glycolysis enter fermentation. • Two NADH molecules are used to convert pyruvate into lactic acid. • As the NADH is used, it converts back to NAD+. 2. TWO molecules of NAD+ are recycled back to glycolysis. • This allows your body to continue to break down sugar for energy!

19. Alcoholic Fermentation in Plants 1. Pyruvate and NADH from glycolysis enter alcoholic fermentation. • The NADH molecules provide energy to break pyruvate into alcohol and carbon dioxide. • As the NADH are used, they are converted to NAD+. 2. The molecules of NAD+ are recycled back to glycolysis. • The recycling of NAD+ allows glycolysis to continue.

20. Cellular Respiration and Photosynthesis • Cellular Respiration and Photosynthesis are approximately the reverse of each other. • Photosynthesis stores energy. • Cellular Respiration releases it.

21. Photosynthesis and Cellular Respiration—write this down 