B ioc he mi st ry Bioenergetics: How the body converts food to energy

1. BiochemistryBioenergetics:How the body convertsfood to energy

2. Bioenergetics • Metabolism: The sum of all Chemical Reactions involved in maintaining the dynamic state of the cell • Catabolism - breaking down of molecules to supply energy • Anabolism - synthesis of molecules • Biochemical Pathway - a series of consecutive chemical reactions

3. Common Catabolic Pathway Conversion of FOOD to ATP: • FOODproduces C4 and C2 fragments • C4 and C2 fragments enter Citric Acid Cycle • CO2, NADH, FADH2, are produced • Electron Transport produces ATP

4. C4 inner membrane C2 C4 C2 CO2 CO2 C2 CO2 Citric Acid Cycle outer membrane ATP NADH FADH2 e- transport e- transport O2 O2 ATP ATP ATP ATP H2O

5. Cells and Mitochondria Components of a typical cell: • nucleus - replication of cell begins here • lysosomes - remove damaged cellular components • Golgi bodies - package and transport proteins • organelles - specialized structures with specific function • mitochondria - common catabolic pathway

6. Cells and Mitochondria

7. Cells and Mitochondria

8. Mitochondria • Mitochondria • Two membranes • Common Catabolic Pathway • Enzymes located in folds or “Crista” • Transport thru the inner membrane occurs with the help of Protein Gates

9. Mitochondrion

10. Common Catabolic Pathway 2 Parts: • Citric Acid Cycle • or Tricarboxylic Acid Cycle • or TCA cycle • or Kreb’s Cycle • Oxidative Phosphorylation • or Electron Transport • or Respiratory Chain 1 2

11. Compounds - ADP • Adenosine diphosphate (ADP)

12. triphosphate Compounds - ATP • AMP, ADP, ATP High energy phosphate anhydride bonds

13. Compounds - ATP • ATP • We make about 88 lbs. of ATP a day!!! • Used for: • muscle contraction • nerve signal conduction • biosynthesis

14. Fig. 26.6, p.651

15. NAD+ FAD Compounds - Redox • NAD+ and FAD • Oxidizing agents • Actually coenzymes • Contain an ADP core (part of R or R’)

16. to ET Compounds - Redox • NAD+ is converted to NADH Oxidized form Reduced form

17. to ET Compounds - Redox • FAD is converted to FADH2 Oxidized form Reduced form

18. Compounds • The Acetylcarrying group - Acetyl coenzyme A • Carrying handle is Pantothenic Acid and Mercaptoethylamine

19. Coenzyme A

20. Coenzyme A 2C 3C 4C

21. Fig. 26.8, p.652

22. http://www.youtube.com/watch?v=iXmw3fR8fh0 http://www.youtube.com/watch?v=lvoZ21P4JK8 http://www.youtube.com/watch?v=A1DjTM1qnPM http://www.youtube.com/watch?v=FgXnH087JIk

23. C2 C4 C6 CO2 C5 C4 CO2 Citric Acid Cycle • Acetyl CoA contains a 2 carbon fragment that is carried into the Citric Acid Cycle • Also called the: • Tricarboxylic Acid Cycle • TCA Cycle • Kreb’s Cycle • Acetyl group is split out as CO2

24. Citric Acid Cycle • Step 1 • oxaloacetate will show up in last step • acetyl CoA is the THIO ESTER of acetic acid (CoA is Co Enzyme A)

25. Citric Acid Cycle • Step 1B • citrate or citric acid produced • citrate has 6 C (How many acid groups?)

26. Fig. 26.8, p.652

27. Citric Acid Cycle • Step 2 • dehydration to cis-Aconitate • hydration to isocitrate • enzymes required for each Rx

28. Fig. 26.8, p.652

29. Citric Acid Cycle • Step 3 • oxidation and decarboxylation • CO2 is from the ???

30. Fig. 26.8, p.652

31. Citric Acid Cycle • Step 4 • Where did the CO2 come from???

32. Fig. 26.8, p.652

33. Citric Acid Cycle • Step 5 • GTP is Guanosine triphosphate (as good as ATP!)

34. Fig. 26.8, p.652

35. Citric Acid Cycle • Step 6 • Oxidation with FAD • Fumaric Acid is trans-Fumaric Acid • Barbiturate is an inhibitor of Succinate dehydrogenase

36. Fig. 26.8, p.652

37. Citric Acid Cycle • Step 7 • hydration reaction • fumarase is enzyme

38. Citric Acid Cycle • Step 8 • oxidation using NAD+ • product is oxaloacetate!

39. Fig. 26.8, p.652

40. 4 H+ + 4 e- + O2 2 H2O Electron (and H+) Transport • End products of the Citric Acid Cycle Reduced (or spent) Coenzymes • NADH • FADH2 • Carry H+ and e- and yield energy when combining with oxygen:

41. Electron (and H+) Transport • Many Enzymes are involved in ET • Enzymes are imbedded in inner membrane of the mitochondria • Enzymes are in a particular sequence • each accepts electrons • increasing affinity for electrons • Final acceptor of electrons is molecular O2 to make water O2

42. Fig. 26.10, p.656

43. Electron Transport chain - youtube http://www.youtube.com/watch?v=xbJ0nbzt5Kw http://www.youtube.com/watch?v=Idy2XAlZIVA http://www.youtube.com/watch?v=A32CvcfA_K0&feature=PlayList&p=F09BC040A0B953F8&playnext=1&playnext_from=PL&index=10 http://www.youtube.com/watch?v=1engJR_XWVU

44. O2 2 H+ 2 H+ 2 H+ Lipid bilayer b Flavo- protein Q enzyme FeS protein a3 a c c1 ATPase b cytochromes NADH NAD+ FADH2 FAD overall3 ATP produced overall2 ATP produced 2 H+ + 2 e- + 1/2 O2 H2O Electron (and H+) Transport • Many Enzymes are involved in Oxidative Phosphorylation O2- ATP

45. The Energy Yield from a C2 • Each NADH produces 3 ATP • Each FADH2 produces 2 ATP (Each pair of H+produces 1 ATP) • For each C2 unit (acetyl CoA) we produce... • 1 GTP directly (same as 1 ATP) from step 5 TCA • 3 NADH in ET (3 x 3 = 9 ATP) Indirect • 1 FADH2 in ET (1 x 2 = 2 ATP) Indirect For a total of ..................... 12 ATP (and some waste CO2) Indirect (from ET) $

46. Conversion of ATP How does the body utilize this Chemical Energy? • Conversion to Other Forms • biosynthesis • Electrical Energy • ion gradients (K+, Na+) • Mechanical Energy • muscle contraction • Heat Energy • maintain 37 oC or 98.6 oF

47. contraction Muscle Contraction Chemical Energy converted to Mechanical Energy: • Thick (myosin) and thin (actin) filaments • Hydrolysis of ATP causes the interaction of the filaments (muscle contraction)