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Chapter 7

Chapter 7. Cellular Respiration. What was the relationship between Photosynthesis and Respiration?. Photosynthesis. 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2. Respiration. Cellular Respiration. Process in which cells make ATP by breaking down organic compounds. Burn a marshmallow

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Chapter 7

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  1. Chapter 7 Cellular Respiration

  2. What was the relationship between Photosynthesis and Respiration? Photosynthesis 6CO2 + 6H2O C6H12O6 + 6O2 Respiration

  3. Cellular Respiration • Process in which cells make ATP by breaking down organic compounds. • Burn a marshmallow Energy is released from the bonds of sugar

  4. Cellular Respiration Occurs in 3 steps: • Glycolysis - If O2, (Aerobic respiration) continues into: • The Krebs Cycle • Electron Transport Chain Or if not O2(Anaerobic respiration) Fermentation

  5. Glycolysis • Process that takes a 6 carbon sugar and breaks it down (oxidizes) it to produce two molecules of the 3 – Carbon compound Pyruvic acid (Pyruvate). • Occurs in the cytosol • Animation - Smith G3P G3P

  6. 4 Steps: Animation - McGraw 1. 2ATP releases 2P. These P’s attach onto glucose. (2 ADP result) P – C – C – C – C – C - C - P 2. The above molecule splits into 2, 3-C molecules of G3P (PGAL) C – C – C- P C – C - C - P 3. G3P is oxidized(loss of e-) & adds on an additional P. P – C – C - C - PP – C - C – C - P Produces 2, 3 – C compounds 2NAD+ (nicotinamide adenine dinucleotide) are reduced, pick up the H’s to become 2NADH + 2H+. 4. P’s are now removed. Produces 2 molecules of Pyruvic acid (Pyruvate). The 2 P’sfrom each Pyruvic acid are used to make 4 molecules of ATP

  7. 2 G3P 2 G3P 2 ATP needed as Activation energy 4 ATP & 2 NADH are produced & 2 molecules of Pyruvic Acid

  8. Energy balance account: • 2 ATP needed in Step 1 + 4 ATP from Step 4 2 ATP netted from Glycolysis

  9. Fermentation IF no oxygen is present then Fermentation results. No additional ATP are produced after Glycolysis 1. Alcoholic Fermenation – yeast (and some bacteria or plant) 2. Lactic Acid Fermentation – bacteria (& muscles when little O2 present)

  10. Lactic Acid Fermentationproduces Lactic Acid Pyruvic acid is converted into Lactic Acid w/ aid of an enzyme, an H from NADH + a H+ NADH is oxidized to become NAD+ C – C – C C – C – C Used in food processing to sour foods such as yogurt, sour cream, sauerkraut, buttermilk.

  11. Muscle Fatigue • Also occurs in muscle cells during strenuous activities (not enough O2). Lactic Acid builds up in muscle cells, acid irritates cells resulting in pain and cramping – Feel the burn 2ATP is better than none

  12. Alcoholic Fermenation produces ethyl alcohol Pyruvic acid releases a CO2molecule C – C – C C – C + CO2 NADH is oxidized & also release 2 H. These are added to the 2 C compound. Forms ethyl alcohol Basis of wine & beer making. Also necessary in the baking industry to make bread rise (those bubbles are CO2 bubbles and ethyl alcohol is produced.

  13. Alcoholic Fermentation Lactic Acid Fermentation

  14. G3P G3P

  15. If alcoholic fermentation occurs in the rising of bread, why don’t you get drunk from eating bread?

  16. So how efficient is fermentation at releasing energy from glucose? • Calorie is the measure of the amount of energy in food • Kilocalorie (kcal) is 1000 calories (“heat”) • 1 mole of C6H12O6 contains 686 kcal. • It takes 7.3 kcal to make 1 ATP Efficiency of glycolysis = 2 x 7.3 ATP X 100% 686 kcal = 2.1%

  17. With something the size of you, a blue whale or a giant red wood tree, would 2 ATP/glucose molecule be enough to power them? Aerobic respiration is ~20 times more efficient at extracting ATP energy from glucose than is Glycolysis alone.

  18. Overview of Aerobic Respiration

  19. Steps in Aerobic Respiration: • Begins as Glycolysis netting 2 ATP per molecule of glucose. • Krebs cycle – oxidation of glucose/pyruvic acid is completed • Electron Transport Chain – NADH that was reduced from Krebs is used to make ATP. This is where all the action is (ATP production)!

  20. The Krebs cycle and the Electron Transport chain occur in the Mitochondrial matrix & Cristae

  21. CO2

  22. To start this all off, following Glycolysis: • Coenzyme A reacts w/ Pyruvic acid (3 Carbon) to produce acetyl coenzyme A(acetyl CoA), a 2 carbon compound with the release of CO2. 1 NAD+ becomes reduced accepts a H to form NADH + H+. C – C – C C – C + CO2 + NADH Animation

  23. Krebs Cycle (aka: Citric Acid cycle): Breaks down acetyl CoA to release CO2, H atoms and produce ATP. Hans Kreb (1900 – 1981) German/British. Krebs Cycle – 1957 Animation – Smith Animation – McGraw GTP is Guanosine Triphosphate – another energy transfer molecule

  24. Per molecule of Glucose, how many times must the Kreb Cycle cycle? 2 times releasing 6 molecules of CO2

  25. 5 Steps: All take place in the mitochondrial matrix • 2 carbon acetyl CoA combines with 4 carbon oxaloacetic acidCitric acid (6 C’s). Coenzyme A is regenerated. • Citric acid releases CO2 and a H, now a 5-C compound. NAD+ is now NADH + H+ • 5 C compound releases another CO2 & a H, forming a 4-C compound & producing NADH. 1 ATP molecule is produced also • 4-C compound releases 2H to produce FADH2 from FAD (flavin adenine dinucleotide). FAD is another electron acceptor. • 4-C compound releases another H to produce oxaloacetic acid. NAD+gets the H to become NADH. Now we are back to the beginning of the Krebs cycle!

  26. Summary of Krebs cycle: • 2 pyruvic acid molecules enter the cycle. So each molecule needs to go through the cycle - cycles 2 times • 2 turns through produces: • 6 NADH (2 more from Acetyl CoA) • 2FADH2 • 2 ATP • 4 CO2 (2 more from Acetyl CoA)

  27. From Glycolysis, 2 NADH were produced and from Pyruvic acid to acetyl CoA, 2 more was produced (2 molecules of acetyl Co A started it). Add that to the 6 from Krebs and that totals 10 NADH to go into the Electron transport chain along with the 2 FADH2.

  28. Electron Transport Chain Occurs on the cristae of the mitochondria • What will happen here: • NADH and FADH2will provide the energy to produce 34 ATP molecules. • Electrons (H’s) from above are passed down each step of the Electron Transport Chain & release energy at each step. • This energy pumps protons from mitochondrial matrix to other side of membrane (Chemiosmosis again!) using ATPsynthase. • Animation – Smith • Animation - McGraw

  29. Electron Transport Chain

  30. Acetyl CoA production Krebs Cycle Electron Transport Chain

  31. Okay, so where does Oxygen come into play in Aerobic Respiration? • When the electrons get to the final step in the Electron Transport Chain, these electrons need to be unloaded. • Oxygen accepts the last electrons from the last molecule in the chain. • It also accepts protons from NADH and FADH2. • 4e- + 4p+ + O2 2 H2O

  32. Energy Yield from Aerobic Respiration: • From 1 molecule of glucose: Glycolysis2 ATP Krebs cycle 2 ATP Electron Transport Chain34 ATP 38 ATP 38 ATP yielded from Aerobic Respiration per molecule of glucose

  33. ATP Accounting

  34. Song time A Summary

  35. Efficiency rating 38 ATP x 7.3 kcal x 100% 686 kcal = 40 % 38 ATP from Aerobic Respiration = 19x • ATP from Anaerobic Respiration Quiz time!!

  36. Summary C6H12O6 6O2 6CO2 + 6H2O + + 38 ATP This energy will be used for growth and metabolism.

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