1. Cellular Respiration Where do animal cells get their energy?

2. Remember  Energy used by all Cells. Organic molecule containing high- energy Phosphate bonds

3. How Do We Get Energy From ATP? in By breaking the high- energy bonds between the last two phosphates in ATP

4. Cellular Respiration The process of cell catabolism in which cells turn food into usable energy in the form of ATP. In this process glucose is broken down in the presence of molecular oxygen into six molecules of carbon dioxide, and much of the energy released is preserved by turning ADP and free phosphate into ATP. Cellular respiration occurs as a series of chemical reactions catalyzed by enzymes, the first of which is glycolysis, a series of anaerobic reactions in which glucose (a 6-carbon molecule) is split into two molecules of lactate (a 3-carbon molecule), producing a net gain of two ATP molecules. In a series of aerobic reactions, lactate is converted to pyruvate, which enters the mitochondrion and combines with oxygen to form an acetyl group, releasing carbon dioxide. The acetyl group (CH 3 CO) is then combined with coenzyme A as acetyl coenzyme A, and enters the Krebs cycle. During this series of reactions, each acetyl group is oxidized to form two molecules of carbon dioxide, and the energy released is transferred to four electron carrier molecules. The electron carrier molecules then release their energy in a process that results in the pumping of protons (hydrogen ions) out across the inner membrane of the mitochondrion. The potential energy of the protons generated by one acetyl group is later released when they recross the membrane and are used to form three molecules of ATP from ADP and phosphate in the process of oxidative phosphorylation. The pyruvate from one molecule of glucose drives two turns of the Krebs cycle. Thus, during cellular respiration one molecule of glucose, as well as oxygen, ADP, and free phosphate are catabolized to yield six molecules of carbon dioxide and an increase in usable energy in the form of eight molecules of ATP.

5.  Glycolysis : the breakdown of glucose by enzymes, releasing energy and pyruvic acid.  Pyruvic Acid : organic acid that occurs as an intermediate in many metabolic processes, especially glycolysis  Anaerobic Respiration : A form of cellular respiration that occurs when oxygen is absent or scarce. The process of generating energy by the oxidation of nutrients and using an external electron acceptor other than oxygen.  Fermentation : enzymatically controlled anaerobic breakdown of an energy-rich compound  Aerobic Respiration : A form of cellular respiration that requires oxygen in order to generate energy. The process of generating energy by the full oxidation of nutrients through Krebs cycle where oxygen is the final electron acceptor.

6. Where Does Cellular Respiration Take Place?  It actually takes place in two parts of the cell: * Glycolysis occurs in the Cytoplasm * Krebs Cycle & ETC Take place in the Mitochondria

7. Review of Mitochondria Structure  Smooth outer Membrane  Folded inner membrane  Folds called Cristae  Space inside cristae called the Matrix

8. Explain: Where do our cells get energy?  6-C sugars are the MAJOR source of energy for cell  What type of macromolecule are 6-C sugars?  Carbohydrates  Cells break down glucose a 6-C sugar to make ATP “energy”

9. 6 Carbon Sugars: They even count the sugars for you…

10. Cellular Respiration (3-stages)  Glycolysis  Krebs Cycle (Citric Acid Cycle)  Electron Transport Chain (ETC) Glucose Glycolysis Krebs cycle Electron transport Fermentation (without oxygen) Alcohol or lactic acid Glucose Glycolysis Krebs Cycle Electron Transport Fermentation (without oxygen) Alcohol or lactic acid

11. Overall Chemical Process C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + usable energy Sugar + Oxygen  Carbon dioxide + Water + ATP

12. Flowchart of Cellular Respiration Glucose (C 6 H 12 0 6 ) + Oxygen (0 2 ) Glycolysis Krebs Cycle Electron Transport Chain Carbon Dioxide (CO 2 ) + Water (H 2 O) + ATP

13. Glycolysis  Where  Cytoplasm  NO O 2 required  Energy Yield  net gain of 2 ATP at the expense of 2 ATP  6-C glucose  TWO 3-C pyruvates  Free e - and H + combine with organic ion carriers called NAD +  NADH + H + (nicotinamide dinucleotide)

14. Glucose To the electron transport chain Glycolysis: 2 Pyruvic acid

15. Glucose To the electron transport chain Glycolysis step 1 2 Pyruvic acid

16. Glucose To the electron transport chain Glycolysis Step 2 2 Pyruvic acid

17. C.R. Reactions  Glycolysis  Series of reactions which break the 6- carbon glucose molecule down into two 3- carbon molecules called pyruvate  Process is an ancient one- all organisms from simple bacteria to humans perform it the same way  Yields 2 ATP molecules for every one glucose molecule broken down  Yields 2 NADH per glucose molecule

18. Summary  In Glucose (6-C) 2 ATP  Out 2 pyruvate; 2(3- C) 2NADH a net of 2 ATP

19. Questions  Where does glycolysis take place? ____________________________________________  It needs _______ ATP to work.  It provides _______ ATP a net gain of _______.  Breaks glucose into TWO ___________.  It is an Aerobic or Anaerobic process?

20. After Glycolysis After glycolysis, about 90 percent of the energy in glucose is still unused. Oxygen is required to extract the rest of the energy (aerobic process).

21. Still Need a review? Click on the picture.

24. Aerobic Cellular Respiration  Oxygen required=aerobic  2 more sets of reactions which occur in a specialized structure within the cell called the mitochondria  1. Kreb’s Cycle  2. Electron Transport Chain

25. Krebs Cycle aka Citric Acid Cycle

26. A Little Krebs Cycle History  Discovered by Hans Krebs in 1937  He received the Nobel Prize in physiology or medicine in 1953 for his discovery  Forced to leave Germany prior to WWII because he was Jewish

27. The Krebs Cycle Citric Acid Production Mitochondrion

28. Kreb’s Cycle  Completes the breakdown of glucose  Takes the pyruvate (3-carbons) and breaks it down, the carbon and oxygen atoms end up in CO 2 and H 2 O  Hydrogens and electrons are stripped and loaded onto NAD + and FAD to produce NADH and FADH 2  Production of only 2 more ATP but loads up the coenzymes with H + and electrons which move to the 3 rd stage

29. Krebs Cycle  Requires Oxygen (Aerobic)  Cyclical series of oxidation reactions that give off CO 2 and produce one ATP per cycle  Turns twice per glucose molecule  Produces two ATP  Takes place in matrix of mitochondria

30. Review of Mitochondria Structure  Smooth outer Membrane  Folded inner membrane  Folds called Cristae  Space inside cristae called the Matrix

31. Krebs Cycle  Each turn of the Krebs Cycle also produces 3 NADH, 1 FADH 2, and 2 CO 2  Therefore, For each Glucose molecule, the Krebs Cycle produces 6 NADH, 2 FADH 2, 4 CO 2, and 2 ATP

32. First Step: Krebs Cycle/Citric Acid Cycle Breakdown of Pyruvic Acid  Where  mitochondria matrix  Pyruvate (3-C)  Acetic acid (2-C)  3rd C forms CO 2  Acetic acid combines with Coenzyme A to form ACETYL-CoA

33. Summary  In Pyruvate NAD CoA  Out CO 2 (as waste) NADH Acetyl-CoA What is releasing Energy with O 2 ?  Aerobic respiration  Where  In the cells mitochondria

34. Second Step: Krebs Cycle or Citric Acid Cycle  Where  Mitochondrial matrix  Energy Yield  2 ATP and more e -  Acetyl-CoA (2-C) combines with 4-C to form 6-C CITRIC ACID  Citric Acid (6-C) changed to 5-C then to a 4-C  Gives off a CO 2 molecule  NAD+ and FAD pick up the released e -  FAD becomes FADH 2  NAD + becomes NADH + H +  Cycle ALWAYS reforming a 4-C molecule

35. Krebs Cycle

36. Still Need a review? Click on the picture. Citric Acid Producti on Mitochondrion

39. Electron Transport Chain Aka ETC

40. Electron Transport Chain  Electron carriers loaded with electrons and protons from the Kreb’s cycle move to this chain-like a series of steps (staircase).  As electrons drop down stairs, energy released to form a total of 32 ATP  Oxygen waits at bottom of staircase, picks up electrons and protons and in doing so becomes water

41. ETC  Where  inner membrane of mitochondria  Energy Yield  Total of 32 ATP  O 2 combines with 2 H + to form H 2 O  Exhale (waste product) - CO 2, H 2 O comes from cellular respiration

42. Electron Transport Chain ATP Production ATP synthase Channel Electron Transport Hydrogen Ion Movement Inner Membrane Matrix Intermembrane Space Mitochondrion

46. Other ETC videos  http://www.science.smith.edu/departments/Biology/Bio231/etc.html

47. So where did all the ATP come from again…

48. Total ENERGY Yield  Glycolysis  2 ATP  Krebs Cycle  2 ATP  ETC  32 ATP  Total  36 ATP

50. What happens if no O 2 ?  Cellular respiration process STOPS… but life needs to go on …

51. Anaerobic respiration

52. Fermentation  Anaerobic respiration (requires no oxygen)  Only 2 ATP are made in anaerobic respiration so it is not as good as aerobic respiration (32 ATP)  Both begin with glycolysis (remember this process was anaerobic.)  No Krebs (citric acid) cycle or electron transport chain

53. Two Types of Fermentation Alcoholic Fermentation -Used by yeasts and a few other micro-organisms with ethyl alcohol and carbon dioxide as waste products. -Causes bread to rise.

54. Lactic Acid Fermentation -Lactic acid is produced from pyruvic acid. -Produced in muscles during rapid exercise when enough oxygen is not present. -Unicellular organisms also produce lactic acid as a waste product. -Prokaryotes are used in the production of cheese, yogurt, buttermilk, sour cream, pickles, sauerkraut, and kimchi.

56. Anaerobic Respiration Glycolysis Glucose Pyruvate + 2 ATP Followed by one of these 2 processes. Only 2 ATP are made in anaerobic respiration so it is not as good as aerobic respiration (36 ATP). Alcoholic Fermentation Pyruvate ethyl alcohol + CO 2 - Carried out by yeast & some bacteria. -Used in brewing beer & making cakes. Lactic Acid Fermentation Pyruvate Lactic Acid -Carried out by your muscle cells when you are exercising hard (need ATP) -Causes muscle cramps & soreness.

57. Aerobic vs. Anaerobic  Anaerobic DOES NOT require oxygen.  It is …  Simple  fast  produces smaller amounts of energy  Aerobic DOES requires oxygen  It…  Yields large amounts of energy  But is not simple, fast or efficient What is the energy molecule that is created? ATP

58. Releasing Energy with out Oxygen  Anaerobic Respiration  NO Additional ATP is Formed  No Oxygen leads to Fermentation  Two Types  Lactic Acid Fermentation  Alcoholic Fermentation

61. What are the 2 chemical equations? Alcoholic fermentation  pyruvic acid + NADH → alcohol + CO ₂ + NAD ⁺ Lactic acid fermentation  pyruvic acid + NADH → lactic acid + NAD ⁺ What are the differences?

62. Review Time…

64. Step 1 Glycolysis occurs in the cytoplasm. Glucose is broken in half to form two pyruvate molecules. A small amount of energy (ATP) is also produced. Glucose Glycolysis Pyruvate ATP Energizes 2 electron carriers.(NAD+ NADH)

65. Step 2: Kreb’s Cycle (Citric Acid Cycle) occurs inside the mitochondria. Pyruvic Acid Kreb’s Cycle e- NADH ATP Citric Acid CO 2

66. Kreb’s Cycle/ Citric Acid Cycle cont… -3 Products from Kreb’s Cycle… 1. Carbon Dioxide released (like in your breath). 2. ATP provides energy for cellular activities. 3. High-energy electron (carried by electron carriers) that can be used to generate large amounts of ATP.

67. Step 3: Electron transport chain occurs in the mitochondria. NADH e- Oxygen we breathe Water 32 ATP We use for energy Electrons move down the electron transport chain. Electrons are caught by oxygen to make water. 32 ATP are also made.

68. Electron Transport Chain -Uses the high-energy electrons from the Kreb’s cycle to convert ADP to ATP. -Electrons are passed from one carrier protein to the next and finally combine with hydrogen ions & oxygen to form water.