Cellular Respiration Chapter 4.4

1. Cellular RespirationChapter 4.4 Dr. Bill Stafford 2014

2. KEY CONCEPT The overall process of cellular respiration converts sugar into ATP using oxygen.

3. Cellular Respiration – Chap. 4.4 • Definition – the process by which the cell breaks down food molecules to release the energy stored in them and use that energy to form ATP • Chemical reaction C6H12O6 + 6O2  6CO2 + H2O + energy (ATP) sugar + oxygen carbon + water dioxide

4. Cellular Respiration – Chap. 4.4 • Four stages of cellular respiration • Glycolysis – anaerobic – does not require oxygen • Intermediate stage – where the products of glycolysis enter the mitochondria - aerobic • Citric acid cycle (Krebs cycle) – aerobic – requires oxygen • Electron transport chain (ETC) - aerobic

5. Cellular Respiration • Mitochondria – organelle where citric acid cycle and ETC are located – site of cellular respiration • Double membraned structure with the inner membrane highly folded • The citric acid cycle occurs in the inner membrane spaces • The ETC takes place in the inner membrane

6. Cellular Respiration – Chap. 4.4 • Glycolysis – first stage of the breakdown of glucose • Takes place in the cytoplasm • Anaerobic – does not require oxygen • Gives a net of 2 ATP for each glucose molecule

9. Cellular Respiration – Chap. 9.3 • Intermediate step – where the two pyruvate molecules produced from one glucose molecule during glycolysis enter the mitochondria – requires oxygen (aerobic) • Produces 1 NADH for each pyruvate molecule or 2 NADH for each glucose molecule • Ends up as a 2-carbon molecule Acetyl-CoA and 2 CO2 molecules • Also gives 1 NADH per pyruvate molecule and 2 NADH per glucose molecule

10. Cellular Respiration – Chap. 4.4 • Intermediate step (cont.) 2 pyruvate  2 acetyl-CoA + 2CO2 + 2NADH

11. Cellular Respiration

12. Cellular Respiration – Chap. 4.4 • Citric acid cycle (Krebs cycle) – series of chemical reactions that breaks down acetyl-CoA into 2 CO2 molecules and releases more energy that was stored in the chemical bonds of acetyl-CoA • Takes place in the space inside the inner membrane of the mitochondria called the matrix • Requires oxygen – aerobic • Produces 2 ATP

13. Cellular Respiration – Chap. 4.4 • Citric acid cycle (cont.) For each citric acid cycle Acetyl-CoA  2CO2 + 3NADH + 1FADH2 + 1ATP For each glucose molecule 2acetyl-CoA  4CO2 + 6NADH + 2FADH2 + 2ATP

15. Cellular Respiration – Chap. 9.3 • Electron transport chain (ETC) – takes the energy from the energized electron carried by NADH and FADH2 and uses that energy to produce ATP • Requires oxygen – aerobic • Located in the inner membrane • Electron is passed from step to step to release the energy in the electron slowly and capture the energy • Makes 34 ATP

16. Cellular Respiration – Chap. 4.4 • ETC (cont.) • 1 NADH gives 3 ATP • 1 FADH2 gives 2 ATP • 2 NADH come from glycolysis, 2NADH comes from intermediate step, and 6 NADH comes from citric acid cycle for each glucose – this gives 10 NADH for each glucose molecule which gives 30 ATP from the ETC from NADH • 2 FADH2 comes from citric acid cycle and gives 4 ATP from the ETC

17. Cellular Respiration – Chap. 4.4 • The final electron acceptor at the end of the ETC is oxygen • The ETC will shut down if no oxygen is available because there is no place for the electrons to go 2e- + 2H+ + O  H2O

19. Fermentation – Chap. 4.5 • Definition - Anaerobic process that allows for the net production of 2 ATP if no oxygen is available • Happens in the cytoplasm • 2 major types of fermentation • Lactic acid fermentation – this process allows the NADH molecules produced by glycolysis to give up their electrons and produce NAD+ so that glycolysis can continue to produce 2 ATP Pyruvate + NADH  lactic acid + NAD+ Occurs in us and other animals if we run out of oxygen

21. Fermentation – Chap. 4.5 • 2 major types – (cont.) • Alcoholic fermentation – produces CO2 and ethyl alcohol from pyruvate and NADH and produces NAD+ to allow glycolysis to continue and produce 2 ATP • CO2 production by yeast is what causes bread to rise • Alcohol is used by the beer and wine industry Pyruvate + NADH  ethyl alcohol + NAD+ + 2CO2

23. Fermentation Lactic acid fermentation takes place in our muscles when we over exercise and use up our oxygen – the lactic acid makes our muscles sore Yeast does alcoholic fermentation and this process is used to make beer and wine and the CO2 produced by yeast is what makes bread rise

27. Fermentation • Comparison of fermentation and cellular respiration • Cellular respiration produces 38 ATP aerobically from each glucose molecule using the mitochondria while fermentation produces 2 ATP anaerobically from each glucose molecule • Fermentation takes place only in the cytoplasm • Make a Venn Diagram

28. Interactions • Autotrophs and producers • Mostly photosynthesis – can make their own food and energy from sunlight and CO2 • Could be chemosynthesis

29. Interactions • Heterotrophs and consumers • Must eat food produced by autotrophs for energy to produce ATP • Most do cellular respiration • Some live off fermentation

30. Interactions • Cycle in nature between O2 and CO2 Oxygen carbon dioxide

31. Interactions • Photosynthetic organisms produce 2 things needed by heterotrophs – food and oxygen

32. Interactions • Flow of energy through an ecosystem Photosynthesis cellular respiration chloroplast mitochondria