Cellular Respiration: Harvesting Chemical Energy

1. Cellular Respiration: Harvesting Chemical Energy

2. Respiration is the process of extracting stored energy from glucose to make ATP.

3. Cellular Respiration Equation C6H12O6 + 6 O2 6 CO2 + 6 H2O and energy As a result of respiration, energy is released from the chemical bonds found in complex organic molecules (food).

4. Aerobic Respiration • Aerobic Respiration is respiration which takes place in the presence of oxygen

5. Respiration is controlled by Enzymes …rate is controlled by enzymes

6. Cell Respiration is divided into 3 stages. (components) 1. Glycolysis 2. Krebs Cycle 3. Oxidative Phosphorylation

7. Glycolysis • Glyco- glucose, -lysis: to split • Universal step in all forms of respiration • Likely used to supply energy for the ancient cells.

8. Glycolysis • Function - To split glucose and produce NADH, ATP and Pyruvate (pyruvic acid). • Location - Cytoplasm. • Occurs in 9 steps…. 6 of the steps use magnesium Mg as cofactors.

10. NAD+ Energy carrier • Nicotinamide Adenine Dinucleotide NAD+ + 2 e- NADH NAD+ = oxidized form NADH = reduced form

11. Requirements for Glycolysis • Glucose • 2 ATP…. As activation energy • 4 ADP • 2 NAD+ • Enzymes

13. The Products of Glycolysis • 2 Pyruvic Acids (a 3C acid) • 4 ATP • 2 NADH

14. Net Energy Result • 2 ATP per glucose • 2 NADH • In summary, glycolysis takes one glucose and turns it into 2 pyruvate, 2 NADH and a net of 2 ATP.

15. Krebs CycleAlso called: Citric Acid Cycleor Tricarboxylic Acid Cycle • Function: Oxidize pyruvic acid to CO2 • Produce: 3NADH, 1FADH2 and 1ATP • Location: Mitochondria matrix

16. Formation of Acetyl CoA:Acetyl CoA is formed when the pyruvate , from glycolysis, combines with Coenzyme A… tis takes place in the matrix.

17. Requirements for Krebs Cycle • Pyruvic acid (3C acid) • Coenzyme A • 3 NAD+ • 1 ADP • 1 FAD • Double this list for each glucose.

20. Products of Krebs Cycle • 3 CO2 • Acetyl CoA • 3 NADH • 1 ATP • 1 FADH2 • Double this list for each glucose.

21. Krebs Cycle • Produces most of the cell's energy in the form of NADH and FADH2… not ATP • Does NOT require O2 • The CO2 produced by the Krebs cycle is the CO2 animal exhale when they breathe.

22. Oxidative Phosphorylation • Process of extracting to energy from NADH and FADH2 to form ATP. • Function: Convert NADH and FADH2 into ATP. • Location: Mitochondria cristae.

23. Oxidative Phosphorylation • NADH or FADH2 • ADP • O2

24. Oxidative Phosphorylation • Requires the Electron Transport Chain… the Electron Transport Chain is a collection of proteins, embedded in the inner membrane, used to transport the electrons from NADH and FADH2

25. Cytochrome c • Cytochrome c: is one of the proteins of the electron transport chain… often used by geneticists to determine relatedness… exists in all living organisms. • The Cytochromes alternate between RED and OX forms and pass electrons down to O2

27. ATP Yield • Each NADH energizes 3 ATP • Each FADH2 energizes2 ATP

28. Chemiosmotic Hypothesis • ETC energy is used to move H+ (protons) across the cristae membrane. • ATP is generated as the H+ diffuse back into the matrix through ATP Synthase

30. ATP Synthase • Uses the flow of H+ to make ATP. • Works like an ion pump in reverse, or like a waterwheel under the flow of H+ “water”.

32. Alcoholic Fermentation • Carried out by yeast, a kind of fungus.

34. Alcoholic Fermentation • Uses only Glycolysis. • An incomplete oxidation - energy is still left in the products (alcohol). • Does NOT require O2 • Produces ATP when O2 is not available.

36. Lactic Acid Fermentation • Uses only Glycolysis. • An incomplete oxidation - energy is still left in the products (lactic acid). • Does NOT require O2 • Produces ATP when O2 is not available.

38. Lactic Acid Fermentation • Done by human muscle cells under oxygen debt. • Lactic Acid is a toxin and causes soreness and stiffness in muscles.

39. Fermentation - Summary • Way of using up NADH so Glycolysis can still run. • Provides ATP to a cell even when O2 is absent.

41. Aerobic vs Anaerobic • Aerobic - Respiration with O2 • Anaerobic - Respiration without O2 • Aerobic - All three Respiration steps. • Anaerobic - Glycolysis only.

42. Strict vs. Facultative Respiration • Strict - can only carry out Respiration one way… aerobic or anaerobic. • Facultative - can switch respiration types depending on O2 availability. Ex - yeast

43. ATP yields by Respiration type • Anaerobic - Glycolysis only Gets 2 ATPs per glucose. • Aerobic - Glycolysis, Krebs, and Oxidative Phosphorylation (electron transport chain) Generates many more ATPs per glucose.

44. Aerobic ATP yield • Glycolysis - 2 ATPS, 2 NADHs • Krebs - 2 ATPS, 8 NADHs, 2 FADH2 • Each NADH = 3 ATP • Each FADH2 = 2 ATP

45. ATP Sum • 10 NADH x 3 = 30 ATPs • 2 FADH2 x 2 = 4 ATPs • 2 ATPs (Gly) = 2 ATPs • 2 ATPs (Krebs) = 2 ATPs • Max = 38 ATPs per glucose

46. However... • Some energy is used in shuttling the NADH from Glycolysis into the mitochondria. • Actual ATP yield ~ 36/glucose

47. Yeast • Would rather do aerobic Respiration; it has 18x more energy per glucose. • But, anaerobic will keep you alive if oxygen is not present.

48. Importance of Respiration • Alcohol Industry - almost every society has a fermented beverage. • Baking Industry - many breads use yeast to provide bubbles to raise the dough.

49. Matching Sugar Cane Gin Barley Saki Grapes Tequila Juniper Cones Vodka Agave Leaves Beer Rice Wine Potatoes Rum

50. Question • Why is the alcohol content of wine always around 12-14%? • Alcohol is toxic and kills the yeast at high concentrations.