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LB145 Sec 001-004

LB145 Sec 001-004. Today’s Outline. Announcements: StudyNotes5 AND Homework4 are due on Tuesday Feb 19 th . Honors – come see me if you missed the meeting. Glycolysis and the Krebs Cycle. CO 2. H 2 O. Light. NADP +. ADP. +. P. i. Calvin Cycle. Light Reactions. ATP. NADPH.

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LB145 Sec 001-004

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  1. LB145Sec 001-004

  2. Today’s Outline • Announcements: StudyNotes5 AND Homework4 are due on Tuesday Feb 19th. Honors – come see me if you missed the meeting. Glycolysis and the Krebs Cycle.

  3. CO2 H2O Light NADP+ ADP + P i Calvin Cycle Light Reactions ATP NADPH Chloroplast [CH2O] (sugar) O2 Campbell 8e, Fig. 10.5

  4. Methods of Producing ATP GLYCOLYSIS & CITRIC ACID CYCLE Substrate-level phosphorylation occurs when ATP is produced by the enzyme-catalyzed transfer of a phosphate group from an intermediate substrate to ADP.

  5. Typically, a cell will not convert 100% of its glucose stores for ATP production. When the cell has enough ATP, glycolysis stops – how does this occur?

  6. Typically, a cell will not convert 100% of its glucose stores for ATP production. When the cell has enough ATP, glycolysis stops – how does this occur?

  7. Product Feedback Inhibition

  8. Feedback Inhibition Regulates Glycolysis During glycolysis, high levels of ATP inhibit the enzyme phosphofructokinase, which catalyzes one of the early reactions. This is called allosteric inhibition.

  9. Enzyme Inhibition Substrate Competitive inhibitor Enzyme Noncompetitive inhibitor (c) Allosteric inhibition (b) Competitive inhibition (a) Normal binding

  10. Hexokinase • First step • Requires ATP • Allosteric inhibition by high concentrations of glucose-6-phosphate

  11. Pyruvate kinase • Last step (produces ATP) • Inhibited by high concentrations of ATP or acetyl coenzyme A

  12. Energy investment phase Glucose 2 ADP + 2 2 ATP used P Glycolysis: What do you need to know? Energy payoff phase formed 4 ADP + 4 P 4 ATP 2 NAD+ + 4 e– + 4 H+ 2 NADH + 2 H+ 2 Pyruvate + 2 H2O Net 2 Pyruvate + 2 H2O Glucose 4 ATP formed – 2 ATP used 2 ATP 2 NAD+ + 4 e– + 4 H+ 2 NADH + 2 H+

  13. Track the Carbons and Phosphates: Glucose + ATP  Fructose-P + ADP Fructose-P + ATP  P-Fructose-P P-Fructose-P  P-CCC + P-CCC P-CCC + P-CCC + 2NAD+ + 2Pi P-CCC-P + P-CCC-P + 2NADH P-CCC-P + P-CCC-P + 2ADP  P-CCC + P-CCC + 2ATP P-CCC + P-CCC + 2ADP  Pyruvate + Pyruvate + 2ATP Glycolysis: What do you need to know?

  14. NADPH

  15. 2ATP 2ATP 25 ATP

  16. Campbell: Fig. 9-6-3 Electrons carried via NADH and FADH2 Electrons carried via NADH Oxidative phosphorylation: electron transport and chemiosmosis Citric acid cycle Glycolysis Pyruvate Glucose Mitochondrion Cytosol ATP ATP ATP Substrate-level phosphorylation Substrate-level phosphorylation Oxidative phosphorylation

  17. Pyruvate Processing Pyruvate processing is the second step in glucose oxidation. It is catalyzed by the enzyme pyruvate dehydrogenase in the mitochondrial matrix. In the presence of O2, pyruvate undergoes a series of reactions that results in the product molecule acetyl coenzyme A (acetyl CoA).

  18. Fig. 9-10 CYTOSOL MITOCHONDRION NAD+ NADH + H+ 2 1 3 Acetyl CoA Coenzyme A Pyruvate CO2 Transport protein

  19. Pyruvate Quiz 3. In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate1) loses a carbon, which is given off as a molecule of CO2, 2) is oxidized to form a two-carbon compound called acetate, and 3) is bonded to coenzyme A. These three steps result in the formation of: • acetyl CoA, NAD+, ATP, and CO2. • acetyl CoA, O2, and ATP. • acetyl CoA and NADH. • acetyl CoA, NADH and CO2. • acetyl CoA, NADH, ATP and CO2.

  20. Pyruvate Quiz 4. How many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one molecule of pyruvate? • 3 • 5 • 2 • 6 • 4

  21. Citric Acid Cycle / Krebs Cycle The Citric Acid Cycle and the Krebs Cycle are the SAME THING.

  22. Fig. 9-11 Pyruvate CO2 NAD+ CoA NADH + H+ Acetyl CoA CoA CoA Citric acid cycle 2 CO2 FADH2 3 NAD+ NADH 3 FAD + 3 H+ ADP + P i ATP

  23. 2 2 2 2 2 2 2 2 2 2 2 More accurately…

  24. Krebs Cycle Quiz 5. How does the Krebs Cycle export energy? • Mostly as CO2 • Mostly as ATP • Mostly as FADH2 • Mostly as NADH • Mostly as H2O

  25. Krebs Cycle Quiz 6. Which statement about the citric acid cycle is correct? • The citric acid cycle produces most of the ATP that is subsequently used by the electron transport chain. • The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle. • The citric acid cycle oxidizes glucose to carbon dioxide. • The citric acid cycle depends on the availability of NAD+, which is a product of glycolysis. • The oxidation of compounds by the citric acid cycle requires molecular oxygen.

  26. The Citric Acid Cycle What do you need to know: • Be familiar with the intermediates (Carbons/Oxygens). • What molecules are produced? • How many of each molecule is produced per cycle? • How many of each molecule is produced per glucose? • What gets recycled?

  27. For THURSDAY: • For TUESDAY – SN5 and HW4

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