Laws of thermodynamics

1. Laws of thermodynamics • Energy is never created or destroyed, only transformed • Entropy (disorder) increases

2. Convert energy source to ATP: usable cellular energy Transforming energy light food ATP

3. ATP: Energy Currency for the cell • Phosphate bonds are highly unstable. DG = -7.3 kcal/mol H2O Pi

4. ATP powers many reactions in cells

5. ATP powers many reactions in cells

6. Active transport • Specific transport protein required • Energy required! • Any kind of molecules • Either direction • Can move against gradient • Can transport all molecules • No equilibrium

7. Simple active transport • Energy from ATP

8. Simple active transport • Energy from ATP • Directional transport • One kind of molecule

9. Simple active transport • PMCA transporter removes Ca2+ from cytoplasm • Very low [Ca2+] required for signaling Ca2+ ATP ADP

10. How do we get ATP from Glucose? • Transfer energy stored in glucose to a storage molecule • ATP • NADH • Glycolysis- Oxidizing glucose to pyruvate • Citric Acid Cycle – Oxidizing pyruvate to CO2 • Election Transport – Collecting electrons from NADH and transferring this energy towards making ATP.

11. Carbohydrates • H-C-OH units • Often used for energy by cells • Glucose is a simple 6C sugar

12. Polymer: polysaccharides (complex carbohydrates) starch cellulose glycogen chitin peptidoglycan Carbohydrates

13. Gain of electrons Increased number of bonds to O O pulls e– from C Oxidation H OH O O – – – – – – H – C – H H – C – H H – C – H H – C – OH O = C = O – – H H most reduced most oxidized

14. When one molecule is oxidized, another is reduced Electron carriers (“coenzymes”): NAD+, FAD Oxidation reactions OH O – – – H – C – H H – C – H – H NAD+ NADH reduction oxidation oxidation 2 e–

15. glucose free energy (G) CO2 reaction progress → “Burning” sugars • Glucose → CO2 is highly exergonic • Same reaction as burning paper or wood • Oxidation

16. Glucose → CO2 is highly exergonic Same reaction as burning paper or wood Oxidation “Burning” sugars O = C = O

17. Glucose → CO2 is highly exergonic Same reaction as burning paper or wood Oxidation “Burning” sugars glucose free energy (G) CO2 reaction progress →

18. Glucose → CO2 is highly exergonic Same reaction as burning paper or wood Oxidation “Burning” sugars glucose free energy (G) CO2 reaction progress →

19. Biochemical pathway Enzymes catalyze steps Energy captured in ATP “Burning” sugars glucose free energy (G) CO2 reaction progress →

20. Oxidized molecules have less chemical energy Energetic electrons transferred to carriers “Burning” sugars higher energy lower energy OH O – – – H – C – H H – C – H – H NAD+ NADH reduction oxidation 2 e– glucose free energy (G) CO2 reaction progress →

21. Complete oxidation of glucose 4 stages: Glycolysis Citric acid cycle Electron transport Chemiosmosis Aerobic cell respiration oxidation glucose 6 CO2

22. Partial oxidation of glucose in cytosol 1. Glycolysis Yum! gluT oxidation glucose 2 pyruvate 2 ATP, 2 NADH

23. First step: phosphorylation catalyzed by hexokinase Energy invested Allows facilitated transport 1. Glycolysis P hexokinase glucose glucose 6-phosphate ATP ADP

24. Another phosphorylation step 6C molecule split into two 3C molecules 1. Glycolysis P P P P P glucose 6-phosphate glucose hexokinase PFK ATP ADP ATP ADP

25. Oxidation Energy stored as high-energy e– on NADH 1. Glycolysis P P P P P P P P P NAD+ NADH glucose 6-phosphate glucose hexokinase PFK ATP ADP ATP ADP NAD+ NADH

26. 2 ATP synthesis steps Net gain of 2 ATP per glucose 6C glucose → 2 3C pyruvates 1. Glycolysis P P P P P P P P P P P NAD+ NADH ADP ATP ADP ATP glucose 6-phosphate glucose hexokinase PFK pyruvate ATP ADP ATP ADP NAD+ NADH ADP ATP ADP ATP

27. AKA tricarboxylic acid cycle (TCA), AKA Krebs cycle Occurs in matrix of mitochondria (or cytosol in prokaryotes) 2. Citric Acid Cycle (CAC)

28. “Transition step” Transport into matrix Connects glycolysis to CAC 2. Citric Acid Cycle (CAC) pyruvate o.m. Coenzyme A i.m. NADH NAD+ cytosol matrix CO2 acetyl CoA

29. “Transition step” Large protein complex spans o.m. and i.m. Transporter and enzyme Oxidation of one carbon to CO2 Attachment of coenzyme A 2. Citric Acid Cycle (CAC) pyruvate o.m. Coenzyme A i.m. NADH NAD+ cytosol matrix CO2 acetyl CoA

30. 2C acetyl CoA + 4C = 6C citric acid 2. Citric Acid Cycle (CAC) acetyl CoA CoA citric acid

31. 2 oxidation reactions complete the oxidation of glucose 2. Citric Acid Cycle (CAC) acetyl CoA CoA citric acid NADH CO2 NAD+ NADH CO2 NAD+

32. One GTP synthesized and converted to ATP 2. Citric Acid Cycle (CAC) ATP acetyl CoA CoA citric acid NADH CO2 NAD+ NADH CO2 NAD+ GDP GTP ADP

33. Two more oxidation steps regenerate original 4C molecule 2. Citric Acid Cycle (CAC) ATP acetyl CoA CoA citric acid NADH CO2 FADH2 NAD+ FAD NADH CO2 NAD+ GDP NAD+ GTP NADH ADP

34. Where’s the carbon from glucose? 2. Citric Acid Cycle (CAC)

35. Where’s the carbon from glucose? 6 CO2 Where’s the energy from glucose? 2. Citric Acid Cycle (CAC)

36. Where’s the carbon from glucose? 6 CO2 Where’s the energy from glucose? 4 net ATP (2 from glycolysis, 2 for each pyruvate in CAC) 2. Citric Acid Cycle (CAC)

37. Where’s the carbon from glucose? 6 CO2 Where’s the energy from glucose? 4 net ATP (2 from glycolysis, 2 for each pyruvate in CAC) 10 NADH (2 glycolysis, 2 transition, 6 CAC) 2. Citric Acid Cycle (CAC)

38. Where’s the carbon from glucose? 6 CO2 Where’s the energy from glucose? 4 net ATP (2 from glycolysis, 2 for each pyruvate in CAC) 10 NADH (2 glycolysis, 2 transition, 6 CAC) 2 FADH2 (CAC) 2. Citric Acid Cycle (CAC)