1. Bioenergetics Chapter 3

2. Bioenergetics Converting foodstuffs (fats, proteins, carbohydrates) into energy Chapter 3

3. Metabolism Total of all chemical reactions that occur in the body –Anabolic reactions Synthesis of molecules –Catabolic reactions Breakdown of molecules

4. Cellular Level Look back……

5. Cell Structure Cell membrane –Protective barrier between interior of cell and extracellular fluid Nucleus –Contains genes that regulate protein synthesis Cytoplasm –Fluid portion of cell –Contains organelles (***mitochondria***)

6. Structure of a Typical Cell

7. Even the Smallest Cells… …are huge compared to the “bits and pieces” and chemicals in them. If you had to wait for random action, you’d wait forever!

8. Cellular Chemical Reactions Endergonic reactions –Require energy to be added Exergonic reactions –Release energy Coupled reactions –Liberation of energy in an exergonic reaction drives an endergonic reaction “Harnessed energy to accomplish a task”

9. Example: –“Combustion” of Carbohydrate C 6 H 12 O 6 reacts with 6O 2 to become 6CO 2 and 6H 2 0 and Energy C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 0 + Energy

10. The Breakdown of Glucose: An Exergonic Reaction

11. Can we regulate reactions? Make sure the reactions occur. Make the reactions occur in a timely manner (speed up the reaction). Prevent the reaction from occurring or slow it down – Rate Limiting

12. Enzymes Catalysts that regulate the speed of reactions –Lower the energy of activation –Create specific conditions for reactions

13. Enzymes Factors that regulate enzyme activity –Temperature –pH work in a narrow range – large gain

14. Enzymes Interact with specific substrates –Lock and key model

15. Enzyme-Substrate Interaction

16. Action of Rate-Limiting Enzymes

17. How is energy converted?

18. Energy Systems Overview

19. Currency System Money –Gold, $100’s, $50’s, $20’s, $10’s, $5’s, $2’s, $1’s Dollar coin, fifty cent, quarters, dimes, nickels, pennies. –Exchanged but not destroyed –Recycled?

20. U.S. Currency System A dollar has potential to do work for you. Spend some, but still has potential left Recycle it and it’s ready to go again Only so much in circulation

21. Human Energy Currency System Adenosine Triphosphate – ATP

22. Structure of ATP

23. High-Energy Phosphates Adenosine triphosphate (ATP) –Consists of adenine, ribose, and three linked phosphates Formation Breakdown ADP + P i  ATP ADP + P i + EnergyATP ATPase

24. Where Does ATP Come From? Is it in our food? Can you buy some at the store? – GNC? Does grandma have some in the attic?

25. Where Does ATP Come From? Stored in cells (muscle**) Store limited amounts (heavy molecule) –Use 50 – 100 x body weight in ATP / 24 hrs. Make it from ADP –Recycle “used” ATP

26. Bioenergetics How to make (recycle) ATP - “Phosphorylation” - adding a phosphate

27. Bioenergetics Anaerobic pathways (non-aerobic) –Do not require or involve O 2 –Called direct phosphorylation

28. Bioenergetics Aerobic pathways –Require O 2 molecules –Called oxidative phosphorylation

29. Anaerobic ATP Production Stored ATP –Immediate (1 st ) source of ATP –Amount depends on muscle size –Runs low on substrate almost immediately - ~ 1 sec. –Used during initiation of movement

30. Anaerobic ATP Production ATP-PC system (PC= phosphocreatine) –Stored in skeletal muscle –Source of phosphates –Rapid response but… –Runs low on substrate quickly ~ 1-5 sec PC + ADPATP + C Creatine kinase

31. Anaerobic ATP Production Glycolysis –Occurs in cytoplasm –Fairly rapid response (small lag) ~ 3+ sec –High energy response –High energy because of it’s speed of action –Expensive in terms of energy required –Lasts as long as substrates available ~ 30+ sec –Makes product that can limit its action

32. Anaerobic ATP Production Glycolysis –Energy investment phase Requires 2 ATP –Energy generation phase Produces 4 ATP Produces NADH (carrier molecule) Produces pyruvate or lactate

33. Glycolysis: Energy Investment Phase

34. Glycolysis: Energy Generation Phase

35. The Two Phases of Glycolysis

36. Glycolysis Net ATP production = 4 ATP produced - 2 ATP used 2 ATP available for muscle contraction from each glucose molecule

37. Is That All That Happens? No

38. Oxidation-Reduction Reactions Oxidation –Molecule accepts electrons (along with H + ) Reduction –Molecule donates electrons Nicotinomide adenine dinucleotide (NAD) Flavin adenine dinucleotide (FAD) FAD + 2H +  FADH 2 NAD + 2H +  NADH + H +

39. Conversion of Pyruvic Acid to Lactic Acid Normally, O 2 is available in the mitochondria to accept H + (and electrons) from NADH produced in glycolysis In anaerobic pathways, O 2 is not available H + and electrons from NADH are accepted by pyruvic acid to form lactic acid

40. Conversion of Pyruvic Acid to Lactic Acid

41. So glycolysis is….. 1 x 6 carbon molecule split into 2 x 3 carbon molecules (costs 2 ATP) 2 x 3C molecule rearranged to make 2 x 3C pyruvic acids (makes 2 ATP each) and 4 H + are shuttled by 2NAD to 2 x 3C pyruvic acids to make 2 x 3C lactic acids (if H + s removed from lactic acid = pyruvic acid)

42. A fast method of providing energy for movement without the need for O 2 A self-limiting method *Also a potential provider of H + for aerobic energy production So glycolysis is…..

43. Aerobic ATP Production Part 1 Krebs cycle (citric acid cycle) –Completes the oxidation of substrates –Uses NAD and FAD to shuttle H + s to the Electron Transport System

44. The Krebs Cycle

45. So the Krebs Cycle is…. A 2C molecule added to a 4C molecule (6C) –rearranged to a 5C and then 4C (version) –2 x CO 2 are made –3 x NADH are made –1 x FADH is made –1 x GTP (ATP) is made

46. Aerobic ATP Production Part 2 Electron Transport System “ETS” –Oxidative Phosphorylation

47. Aerobic ATP Production ETS –Electrons removed from NADH and FADH are passed along a series of carriers to drive phosphorylation of ADP to ATP –H + from NADH and FADH are accepted by O 2 to form water – H 2 O (neutral)

48. Formation of ATP in the Electron Transport Chain

49. So for each…… 1 NADH through the ETS = 3 ATP made 1 FADH through the ETS = 2 ATP made

50. The Three Stages of Oxidative Phosphorylation

51. Aerobic ATP Tally – For Glucose

52. Efficiency of Oxidative Phosphorylation Aerobic metabolism of one molecule of glucose –Yields 38 ATP Aerobic metabolism of one molecule of glycogen –Yields 39 ATP Overall efficiency of aerobic respiration is 40% –60% of energy released as heat!!!!!

53. Is Glucose the Only Fuel Source? No

54. Fuels for Phosphorylation Carbohydrates –Glucose (6 carbon molecule) –Glycogen (branched carbon molecules) Glucose stored in muscle cells and liver Glycogenolysis - makes carbons available for metabolism –Occurring in muscle cells - glucose stays in muscle cells –Occurring in liver – glucose put into circulation

55. Fuels for Phosphorylation Fats (18+ carbon molecule) –Primarily fatty acids (FA) Stored as triglycerides Stored in muscle cells and in adipose cells Beta oxidation makes FAs available for Krebs Cycle –Release of FAs from adipose to blood stream –Hormone initiated –All working muscles have access to FAs via cellular storage or via blood stream

56. Fuels for Phosphorylation Proteins –Amino Acids (AA) –Storage is structural (no extra depot) –Carbons are available –Not a primary energy source during exercise (too expensive) –But usable – long duration exercise (up to 15%)

57. What is common between all these fuel sources? - A 2 carbon molecule called….. Acetyl Co-A Fuels for Phosphorylation

58. Relationship Between the Metabolism of Proteins, Fats, and Carbohydrates

59. There’s one other potential fuel source.

60. The Cori Cycle: Lactate As a Fuel Source

61. What’s it all about? Does anybody know? Here’s how I found out. Can You See the “Big Picture” Regarding Aerobic ATP Production?

63. How is control maintained?

64. Control of Bioenergetics Rate-limiting enzymes –An enzyme that regulates the rate of a metabolic pathway Levels of ATP and ADP+P i –High levels of ATP inhibit ATP production –Low levels of ATP and high levels of ADP+P i stimulate ATP production

65. Control of Bioenergetics Rate-limiting enzymes –An enzyme that regulates the rate of a metabolic pathway Levels of ATP and ADP+P i –High levels of ATP inhibit ATP production –Low levels of ATP and high levels of ADP+P i stimulate ATP production Calcium may stimulate aerobic ATP production

66. Action of Rate-Limiting Enzymes

67. Control of Metabolic Pathways

68. Remember….. 1 cell = absolute Whole body = not absolute Where is there interaction between energy systems?

69. Interaction Between Aerobic and Anaerobic ATP Production Energy to perform exercise comes from an interaction between aerobic and anaerobic pathways

70. Interaction Between Aerobic and Anaerobic ATP Production Effect of duration and intensity –Immediate movement Stored ATP –Short-term, high-intensity activities Greater contribution of anaerobic energy systems –ATP-PC and Glycolysis –Long-term, low to moderate-intensity exercise Majority of ATP produced from aerobic sources –Aerobic glycolysis, beta oxidation, protein

71. Questions?

72. End