Chapter 8: Glycolysis and Cellular Respiration

1. Chapter 8: Glycolysis and Cellular Respiration

2. What is Photosynthesis?

3. Glucose • A key energy-storing molecule: • Nearly all cells metabolize glucose for energy • Other organic molecules are converted to glucose for energy harvesting

4. Overview of Glucose Breakdown C6H12O6 + 6O2 6CO2 + 6H2O + ATP + (heat E)

5. Glucose Breakdown • The main stages of glucose metabolism are: • Glycolysis • Cellular respiration

6. Glycolysis • Glycolysis • Occurs in cytosol • Does not require oxygen • Breaks glucose into pyruvate • Yields two molecules of ATP per molecule of glucose

7. Fermentation • If oxygen is absent fermentation occurs • pyruvate is converted into either lactate, or into ethanol and CO2 • If oxygen is present, cellular respiration occurs

8. Cellular Respiration • Occurs in mitochondria (in eukaryotes) • In cytosol (in prokaryotes) • Requires oxygen • Breaks down pyruvate into carbon dioxide and water • Produces an additional 32 or 34 ATP molecules, depending on the cell type

11. Summary of Glycolysis • Each molecule of glucose is broken down to 2 molecules of pyruvate. • A net of 2 ATP and 2 NADH molecules are formed.

12. Fermentation • Occurs under anaerobicconditions • Pyruvate is converted into lactate or ethanol and CO2 • Fermentation does not directly produce more ATP • But is necessary to regenerate NAD+, which must be available for glycolysis to continue

13. Fermentation • Some cells ferment pyruvate to form acids • Human muscle cells can perform fermentation • Anaerobic conditions produced when muscles use up O2 faster than it can be delivered (e.g. while sprinting) • Lactate (lactic acid) produced from pyruvate

15. Fermentation • Some microbes ferment pyruvate to other acids (as seen in making of cheese, yogurt, sour cream) • Some microbes perform fermentation exclusively (instead of aerobic respiration) recipes.howstuffworks.com preparednesspro.files.wordpress.com/2009/08/c...

16. Fermentation • Yeast cells perform alcoholic fermentation • Glucose is fermented to ethanol and CO2

18. Cellular Respiration • Occurs within mitochondria in eukaryotic cells

20. Electron Transport Chain • Most of energy in glucose is stored in electron carriers NADH and FADH2 • Only 4 total ATP produced per glucose after complete breakdown in the Krebs Cycle • NADH and FADH2 deposit electrons into electron transport chainsin the inner mitochondrial membrane • Electrons join with oxygen gas and hydrogen ions to make H2O at the end of the ETCs

22. Chemiosmosis 1. Energy released from electrons as they are passed down the ETC 2. Released energy used to pump H+ across inner membrane • H+ accumulate in intermembrane space 3. H+ form a concentration gradient across the membrane (a form of stored energy) 4. H+ flow back into the matrix through an ATP synthesizing enzyme

23. Chemiosmosis • Flow of H+ provides energy to link 32-34 molecules of ADP with phosphate, forming 32-34 ATP • ATP then diffuses out of mitochondrion and used for energy-requiring activities in the cell

26. Influence on How Organisms Function • Metabolic processes in cells are heavily dependent on ATP generation • Muscle cells switch between fermentation and aerobic cell respiration depending on O2 availability

27. vitalsigns-health.co.uk news.bbc.co.uk

28. The End