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1. Pencil • Science Journal • If you need to take the quiz, see me. • http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__how_the_krebs_cycle_works__quiz_2_.html Please Take Out the Following

2. Name the chief currency of the cells energy and where in the cell it is made. Science Question of the day

3. Chief energy currency of the cell is ATP. It is made in the mitochondria of the cell. Answer

4. Food • Energy • ATP • Mitochondria • Membrane bound organelles • Permeability • Investing and harvesting ATP http://www.sumanasinc.com/webcontent/animations/content/cellularrespiration.html Review Time

5. Cellular respiration: Harvesting of energy from breakdown of organic molecules produced by plants The overall process may be summarized as + energy + + 6 CO2 C6H12O6 6 H2O 6 O2 (heat or ATP) carbon dioxide glucose water oxygen 6.6 An Overview ofCellular Respiration • Cellular respiration is carried out in two stages: • 1. Glycolysis • 2. Oxidation Occurs in the cytoplasm Occurs in the mitochondria

6. Fig. 6.16 An overview of aerobic respiration Oxygen is the terminal electron acceptor in aerobic respiration

7. Glycolysis is the first stage in cellular respiration Takes place in the cytoplasm Occurs in the presence or absence of oxygen Involves ten enzyme-catalyzed reactions These convert the 6-carbon glucose into two 3-carbon molecules of pyruvate 6.7 Using Coupled Reactionsto Make ATP

8. Fig. 6.19 Pyruvate is oxidized Pyruvate is reduced Occurs in animal muscle cells Occurs in yeast cells

9. Fig. 6.17 How glycolysis works 1 2 3 Priming reactions Cleavage reactions Energy-harvesting reactions 6-carbon glucose (Starting material) 2 ATP P P P P 6-carbon sugar diphosphate 6-carbon sugar diphosphate P P P P 3-carbon sugar phosphate 3-carbon sugar phosphate 3-carbon sugar phosphate 3-carbon sugar phosphate NADH NADH 2 ATP 2 ATP 3-carbon pyruvate 3-carbon pyruvate

10. Fig. 6.18 Glycolysis

11. Fig. 6.18 Glycolysis This coupled reaction is calledsubstrate-level phosphorylation

12. The oxidative stage of aerobic respiration occurs in the mitochondria It begins with the conversion of pyruvate into acetyl coA Fig. 6.20 Depending on needs 6.8 Harvesting Electronsfrom Chemical Bonds

13. Fig. 6.21 How NAD+ works 6.8 Harvesting Electronsfrom Chemical Bonds Substrate is oxidized NAD+ is reduced

14. The Krebs Cycle • Takes place in the mitochondria • It consists of nine enzyme-catalyzed reactions that can be divided into three stages • Stage 1 • Acetyl coA binds a four-carbon molecule producing a six-carbon molecule • Stage 2 • Two carbons are removed as CO2 • Stage 3 • The four-carbon starting material is regenerated

15. Fig. 6.22 How the Krebs cycle works 1 2 3 CoA– (Acetyl-CoA) 4-carbon molecule (Starting material) 4-carbon molecule (Starting material) 6-carbon molecule 6-carbon molecule NADH NADH FADH2 4-carbon molecule 5-carbon molecule 4-carbon molecule NADH ATP CO2 CO2

16. Fig. 6.23 The Krebs cycle

18. Fate of Glucose • Glucose is entirely consumed in the process of cellular respiration • It is converted to six molecules of CO2 • Its energy is preserved in • Four ATP molecules • Ten NADH electron carriers • Two FADH2 electron carriers

19. 6.9 Using the Electrons to Make ATP • The NADH and FADH2 carry their high-energy electrons to the inner mitochondrial membrane • There they transfer them to a series of membrane-associated carriers – the electron transport chain • Three of these carriers are protein complexes that pump protons out of the matrix • The electrons are finally donated to oxygen to form water

20. Intermembrane space H+ H+ Inner mitochondrial membrane H+ e– e– FADH2 NADH 2H+ + ½O2 + H+ NAD+ H2O Protein complex I Protein complex II Protein complex III Mitochondrial matrix Fig. 6.24 The electron transport chain NADH activates all three pumps FADH2 activates only two pumps

21. Fig. 6.25 • The proton gradient induces the protons to reenter the matrix through ATP synthase channels • The proton pumps lead to an increase in proton concentration in the intermembrane space • The proton reentry drives the synthesis of ATP by chemiosmosis

22. Intermembrane space Pyruvate from cytoplasm H+ H+ NADH H+ 1. Electrons are harvested and carried to the transport system. 2. Electrons provide energy to pump protons across the membrane. Acetyl-CoA NADH H2O Krebs cycle 1 2 FADH2 3. Oxygen joins with protons to form water. O2 O2 + 2H+ CO2 32 ATP ATP e– e– e– 4. Protons diffuse back in, driving the synthesis of ATP. H+ 2 ATP synthase Mitochondrial matrix Fig. 6.26 An overview of the electron transport chain and chemiosmosis

23. Other Sources of Energy • Food sources, other than sugars, can be used in cellular respiration • These complex molecules are first digested into simpler subunits • These subunits are modified into intermediates • These intermediates enter cellular respiration at different steps

24. Fig. 6.27 How cells obtain energy from foods

25. CH4 Methane SO4 H2S Hydrogen sulfide Sulfate Anaerobic Respiration • The use of inorganicterminal electron acceptors other than oxygen CO2 Archaea

26. Fermentation • The use of organic terminal electron acceptors • The electrons carried by NADH are donated to a derivative of pyruvate • This allows the regeneration of NAD+ that keeps glycolysis running • Two types of fermentation are common among eukaryotes • Lactic fermentation • Ethanolic fermentation