Cellular Respiration: Harvesting Chemical Energy

1. Cellular Respiration: Harvesting Chemical Energy

2. Respiration is the process of extracting stored energy from glucose and storing it in the high energy bonds of ATP.

3. Cellular Respiration Equation Reactants Products C6H12O6 + 6 O2 6 CO2 + 6 H2O and energy • As a result of respiration, energy is released from the chemical bonds and used for “phosphorylation” of ATP. • Phosphorylation is the process of adding a phosphate group to a molecule…. By adding a phosphate ADP it becomes ATP. • The respiration reactions are controlled by ENZYMES.

4. Cellular Respiration • There are two types of Respiration: Anaerobic Respiration and Aerobic Respiration • Some organisms use the Anaerobic Respiration pathway, and some organisms use the Aerobic Respiration pathway.

5. Anaerobes • Anaerobes are organisms that use the Anaerobic Respiration pathway • Most anaerobes are bacteria (not all). • Anaerobes do NOT require oxygen.

6. Aerobes • Aerobes are organisms that use the Aerobic Respiration pathway. • Aerobes require oxygen.

7. Anaerobic Respiration Anaerobic Respiration does NOTrequire oxygen! The 2 most common forms of Anaerobic Respiration are: 1. Alcoholic Fermentation, and 2. Lactic Acid Fermentation

8. The First Stage of Respiration for ALL living organisms, anaerobes or aerobes, is called Glycolysisand takes place in the Cytosol.

9. Glycolysis • glyco means “glucose/sugar”, and • lysis means “to split”. Therefore, • glycolysis means “to split glucose” • This process was likely used to supply energy for the ancient forms of bacteria.

10. Glycolysis • Function - to split glucose and produce NADH, ATP and Pyruvate (pyruvic acid). • Location - Cytosol • Occurs in 9 steps- 6 of the steps use magnesium (Mg) as a cofactor.

11. Reactants for Glycolysis • Glucose • 2 ATP…. As activation energy • 4 ADP and 4P • Enzymes • 2 NAD+(Nicotinamide Adenine Dinucleotide, an energy carrier)

12. Glycolysis 4 ATP’s are produced Pyruvic Acid (3 Carbons) Glucose(6 carbons) 2 ATP’s supply the activation energy Pyruvic Acid (3 Carbons) 2 NAD+ + 2 e- 2 NADH 4 ATP Yield = 2 ATP Net Gain

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

14. Net Result • 2 Pyruvic Acid • 2 ATP per glucose (4 – 2 = 2) • 2 NADH • In summary, glycolysis takes one glucose and turns it into 2 pyruvates (molecules of pyruvic acid), 2 NADH and a net of 2 ATP.

15. Alcoholic Fermentation is carried out by yeast, a kind of fungus.

16. Alcoholic Fermentation • Uses only Glycolysis. • Does NOT require O2 • Produces ATP when O2 is not available.

17. Alcoholic FermentationC6H12O6 2 C2H5OH + 2 CO2 (Ethyl Alcohol or Ethanol) As a result of Alcoholic Fermentation, Glucose is converted into 2 molecules of Ethyl Alcohol and 2 Molecules of Carbon Dioxide.

18. Alcoholic Fermentation Glycolysis Released into the environment 4 ATP’s are produced CO2 (C2H5OH) Pyruvic Acid (3C) Ethyl Alcohol (2C) Glucose (6 carbons) Released into the environment CO2 2 ATP’s supply the activation energy Pyruvic Acid (3C) Ethyl Alcohol (2C) (C2H5OH) 2 NAD+ + 2 e- 2 NADH 2 NAD+ + 2 e- 4 ATP Yield = 2 ATP Net Gain

19. Question • Why is the alcohol content of wine always around 12-14%? • Because Alcohol is toxic and kills the yeast at high concentrations. Oh Yeah…..The Holes in Swiss Cheese are bubbles of CO2 from fermentation.

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

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

22. Lactic Acid Fermentation • Uses only Glycolysis. • Does NOT require O2 • Produces ATP when O2 is not available.

23. Lactic Acid Fermentation • Carried out by human muscle cells under oxygen debt. • Lactic Acid is a toxin and causes fatigue, soreness and stiffness in muscles.

24. Lactic Acid Fermentation Glycolysis 4 ATP’s are produced Pyruvic Acid (3C) Lactic Acid (3C) Glucose (6 carbons) 2 ATP’s supply the activation energy Pyruvic Acid (3C) Lactic Acid (3C) 2 NAD+ + 2 e- 2 NADH 2 NAD+ + 2 e- 4 ATP Yield = 2 ATP Net Gain

25. Fermentation - Summary • Releases 2 ATP from the breakdown of a glucose molecule • Provides ATP to a cell even when O2 is absent.

26. Aerobic Respiration Aerobic Respiration requires oxygen!

27. There are three phases to Aerobic Respiration ... they are: 1. Glycolysis (same as the glycolysis of anaerobic respiration) 2. Krebs cycle (AKA - Citric Acid cycle) 3. Oxidative Phosphorylation and The Electron Transport Chain

28. Phase One: Glycolysis(takes place in the cytoplasm) Glycolysis 4 ATP’s are produced Pyruvic Acid (3C) Glucose (6 carbons) 2 ATP’s supply the activation energy Pyruvic Acid (3C) 2 NAD+ + 2 e- 2 NADH 4 ATP Yield = 2 ATP Net Gain

29. In order for Aerobic Respiration to continue the Pyruvic acid is first converted to Acetic Acid by losing a carbon atom and 2 oxygens as CO2. The Acetic acid then must enter the matrix region of the mitochondria. The CO2 produced isthe CO2animals exhale when they breathe.

30. Phase Two: The Krebs Cycle(AKA the Citric Acid Cycle) Once the Acetic Acid enters the Matrix it combines with Coenzyme A to form a new molecule called Acetyl-CoA. The Acetyl-CoA then enters the Krebs Cycle. CoA breaks off to gather more acetic acid. The Acetic acid is broken down. Sir Hans Adolf Krebs Produces most of the cell's energy in the form of NADH and FADH2… not ATP Does NOT require O2 + 3H 3 NADH

31. Summary As a result of one turn of the Krebs cycle the cell makes: 1 FADH2 3 NADH 1 ATP However, each glucose produces two pyruvic acid molecules…. So the total outcome is: 2 FADH2 6 NADH 2 ATP

32. Phase Three:Oxidative Phosphorylation • Function: Extract energy from NADH and FADH2 in order to add a phosphate group to ADP to make ATP. • Location: Mitochondria cristae.

33. Oxidative Phosphorylation Requires NADH or FADH2 ADP and P O2

34. Oxidative Phosphorylation • Requires the Electron Transport Chain. • The Electron Transport Chain is a collection of proteins, embedded in the inner membrane. • It is used to transport the electrons from NADH and FADH2 . ˜A link to an Internet Animation of the Electron Transport Chain˜ http://vcell.ndsu.nodak.edu/animations/etc/movie.htm

35. The Electron Transport Chain

36. Cytochrome c • Cytochrome c: • is one of the proteins of the electron transport chain; • exists in all living organisms; • is often used by geneticists to determine relatedness.

37. Chemiosmotic Hypothesis • Biologists still don’t know exactly how ATP is made. • The best theory we have is called the Chemiosmotic Hypothesis.

38. The Chemiosmotic Hypothesis • proposes that the Electron Transport Chain energy is used to move H+ (protons) across the cristae membrane, and • that ATP is generated as the H+ diffuse back into the matrix through ATP Synthase.

40. 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”.

41. Comparing Aerobic andAnaerobic Respiration • Aerobic Respiration- • requires a mitochondrion and oxygen • is a three phase process • Anaerobic – • does not require oxygen • consists of one phase only-Glycolysis

42. Strict vs. Facultative Respiration • Strict - can only carry out Respiration only one way… aerobic or anaerobic. Ex - you • Facultative - can switch respiration types depending on O2 availability. Ex – yeast • Aerobes – organisms that require oxygen • Anaerobes - organisms that DO NOT require oxygen • Obligate Anaerobes – oxygen is LETHAL to these organisms • Facultative – organisms that can live with or without oxygen

43. 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

44. However... Some energy (2 ATP’s) is used to shuttle the NADH from Glycolysis into the mitochondria…..So, some biologists teach there is an actual ATP yield of 36 ATP’s per glucose.