1. Chapter 7: Cell Respiration
Cell respiration is the controlled release of energy from organic compounds to produce ATP.
ATP from cell respiration is immediately available as a source of energy in the cell.
Anaerobic cell respiration gives a small yield of ATP from glucose.
Aerobic cell respiration requires oxygen and gives a large yield of ATP from glucose

2. Cell Respiration: Overview
A. Cell respiration is used by all cells to produce ATP
1. Organic molecules contain energy in their molecular structures
a) Each covalent bond in glucose, amino acid, or fatty acid represents stored chemical energy

3. Cells break down (metabolize) their nutrients by slow oxidation (Can use glucose, amino acids, or fatty acids)
a) Covalent bonds are broken (oxidized) by a series of chemical reactions by the use of enzymes
b) When a covalent bond is broken a small amount of energy is released
c) Energy is released in a controlled way in order to trap the released energy into ATP

4. Fermentation (without oxygen)
Chemical Pathways
Section 9-1
Glucose
Krebs cycle
Electron transport
Glycolysis
Alcohol or lactic acid
Fermentation (without oxygen)
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5. Glycolysis is the first step in cell respiration
1. All cells using glucose will start cell respiration in the same way
2. Overview of steps
a) Glucose enters through cell membrane and floats in the cytoplasm
b) Enzymes modify the glucose

6. c) Series of reactions that cut the 6C glucose into two 3C molecules (pyruvate) d) Some covalent bonds are broken and a small amount of energy is released and forms ATP e) 2 molecules of ATP are used to start the reaction and 4 molecules of ATP are produced, so there is a net gain of 2 ATP molecules Glycolysis

8. Anaerobic Respiration
1. Cell respiration: variety of biochemical pathways that can be used to metabolize glucose
2. Anaerobic: do not require oxygen
3. Aerobic: do require oxygen

9. 4. Fermentation: breakdown of organic
4. Fermentation: breakdown of organic molecules for ATP production in an anaerobic way
a) Alcoholic
b) Lactic acid
Alcoholic fermentation
1. Yeast: single-celled fungus that uses alcoholic fermentation for ATP production when no oxygen is present

10. 2. Yeast uses glucose and goes through glycolysis to produce 2 ATP and 2 pyruvate 3. Pyruvate is then converted to ethanol, carbon dioxide, and NAD+ 4. Carbon dioxide makes dough rise 5. Ethanol is used in alcoholic drinks

11. New Glarus Brewery

12. E. Lactic Acid Fermentation 1
E. Lactic Acid Fermentation 1. Converts pyruvate into lactic acid (lactate) and NAD+, when oxygen is not present 2. Allows glycolysis to continue, which will produce a small amount of ATP 3. Muscles cells will use lactic acid fermentation during strenuous exercise when they are not getting enough oxygen

13. Lactic Acid Fermentation
Section 9-1
Lactic acid
Glucose
Pyruvic acid
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14. 4. Used by microorganisms, which is used in food products like yogurt and cheese Fermentation clip

15. Examples of Food Products Using Fermentation
Bread: yeast, fungus Yogurt: streptococcus, bacteria Cheese: streptococcus, bacteria Soy sauce: aspergillus, fungus Cured olives: lactobacillus, bacteria

16. Aerobic cell respiration is the most efficient pathway
1. Cells that have a mitochondria
usually use an aerobic pathway for
cell respiration
Steps
Glycolysis: make 2 ATP and 2 pyruvate molecules
2 pyruvate enter mitochondria and are metabolized

17. Pyruvate loses a CO2 molecule and becomes acetyl-CoA
Acetyl-CoA enters the Krebs cycle
Krebs cycle: series of reactions that begins and ends with the same molecule
a) 2 molecules of CO2 are released
b) Some ATP and other molecules are made that will further generate more ATP by using oxygen (Electron Transport Chain)
Summary: Aerobic cell respiration breaks down a glucose molecule and the end products are CO2, water, and ATP

18. Equation: C6H12O6 + 6O2  6H2O + 6CO2 + ATP

20. Electron Transport Chain
Flowchart
Section 9-2
Cellular Respiration
Glucose (C6H1206) +
Oxygen (02)
Glycolysis
Krebs Cycle
Electron Transport Chain
Carbon
Dioxide
(CO2) +
Water
(H2O)
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21. Respiration: An Overview
Section 9-1
Mitochondrion
Electrons carried in NADH
Electrons carried in NADH and FADH2
Pyruvic acid
Glucose
Electron Transport Chain
Krebs Cycle
Glycolysis
Mitochondrion
Cytoplasm
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22. Interactive Respirometer: devices used to measure an organism’s rate of respiration by measuring the oxygen rate of exchange 1. Carbon dioxide that is produced is absorbed by potassium hydroxide 2. Measurement of oxygen exchange can then be taken

26. Cell Respiration: Higher Level
Oxidation and reduction
1. Cellular metabolism is the sum total of all the chemical reactions carried out by an organism
a) Catabolic: breakdown of complex molecules into small molecules (cellular respiration)
b) Anabolic: synthesis of more complex molecules from simpler ones (photosynthesis)

27. Hints
Oil: Oxidation is loss (of electrons)
Rig: Reduction is gain (of electrons)
Oxidation and reduction reactions occur together in a chemical reaction (Redox reaction)
Redox reactions play a key role in the flow of energy through living systems: Electrons that are flowing from one molecule to the next are carrying energy with them

28. C6H12O6 + 6O2  6CO2 + 6 H2O + energy
a) Glucose is oxidized because electrons are transferred from it to oxygen.
b) The protons follow the electrons to produce water.
c) Oxygen atoms on the reactant sided are reduced
d) Large drop in potential energy of the compounds on the product side of the equation

30. B. Glycolysis: sugar splitting
Characteristics
a) Perhaps the first biochemical pathway to evolve
b) Uses no oxygen
c) Occurs in cytosol/cytoplasm
d) No organelles required
e) Occurs in both prokaryotic and eukaryotic cells
f) Hexose sugar, usually glucose, is split in three stages

31. Three stages of glycolysis 1
Three stages of glycolysis 1. Two ATP are used a) Phosphorylation: phosphates from ATP are added to glucose to form fructose-1,6-biphosphate b) Step creates a less stable molecule

32. 2. Lysis: Splitting of fructose-1,6-biphosphate into two 3-carbon sugars called glyceraldehyde-3-phosphate (G3P)

33. Oxidation phase: 2 molecules of G3P undergo oxidation
a) NAD+ (electron carrier) is reduced to form NADH
b) Released energy is used to
add phosphates to the 3-C compound
Enzymes then remove phosphates
to form ATP from ADP
d) End result: 4 ATP, 2 NADH, and 2
pyruvate

34. Summary of glycolysis
a) 2 ATPs are used to start process
b) 4 ATPs are produced for net gain of 2
c) 2 molecules of NADH are produced
d) Pathway involves substrate level phosphorylation, lysis, oxidation, and ATP production

35. e) Occurs in cytoplasm f) Controlled by enzymes: when ATP levels in the cell are high, feedback inhibition will block the first enzyme of the pathway to slow or stop the process g) 2 pyruvate molecules are present at the end of the pathway Glycolysis

36. Link Reaction
1. If oxygen is present after glycolysis, the pyruvate enters the matrix of the mitochondria by active transport
2. Pyruvate is decarboxylated: removal of a carbon atom to form carbon dioxide and 2-C acetyl group
a) CO2 is released as a waste gas
b) Acetyl group is oxidized with the formation of NADH
Acetyl group combines with coenzyme A (CoA) to form acetyl CoA
Acetyl CoA will enter the next step, the Krebs cycle

37. Coenzyme: molecule that aids an enzyme in its action and usually acts as electron donors or acceptors

38. Acetyl CoA can be produced from most carbohydrates and fats
a) If ATP levels are high, then acetyl CoA can be stored as a lipid
b) If ATP levels are low, then acetyl CoA will enter the Krebs cycle

39. Krebs cycle: tricarboxylic acid cycle
1. Overview
a) Occurs in matrix of mitochondria
b) Cycle because it begins and ends with the same substance

40. Steps
Acetyl CoA combines with 4-C oxaloacetate to form 6-C citrate
2. Citrate is oxidized and decarboxylated to from a 5-C compound
a) CO2 is released
b) NAD+ is reduced to NADH

41. 5-C compound is oxidized and decarboxylated to
form a 4-C compound
a) CO2 is released
b) NAD+ is reduced to form NADH

42. 4-C compound undergoes various changes and produces several products
a) NADH
b) Coenzyme FAD is reduced to FADH2
c) Reduction of ADP to make ATP
d) 4-C compound changed into starting compound of oxaloacetate
Krebs cycle
krebstca

43. Summary for one molecule of glucose
a) Krebs cycle runs twice for each glucose molecule since 2 molecules of pyruvate are made in glycolysis
b) 2 ATP
c) 6 NADH
d) 2 FADH2
e) 4 CO2
Special note on CO2: 2 CO2 are released in the link reaction and 4 are released during Krebs cycle, so glucose is completely catabolized and energy is now carried as NADH, FADH2, or stored as ATP

44. Summary of ATP production for glycolysis and Krebs cycle
a) 4ATP made in glycolysis
b) 2 ATP from Krebs cycle
c) 2 ATP were used to start glycolysis
d) Total of 4 ATP gained and made by substrate-level phosphorylation
e) Substrate-level phosphorylation: ATP is made by phosphate group being transferred directly to ADP from phosphate-bearing molecule

45. E. Electron transport chain 1
E. Electron transport chain 1. Electron transport chain: most of the ATP is made, oxygen is needed, and occurs in the inner mitochondrial membrane and cristae membranes of the mitochondria 2. Molecules are embedded in the membranes that are easily oxidized and reduced 3. Electrons (energy) carriers are close together and pass the electrons from one to another because of an energy gradient

46. 4. Each carrier has a slightly different electronegativity and therefore a different attraction for electrons 5. Cytochromes: carriers that are proteins with heme (haem) group 6. Coenzyme Q: carrier that is not a protein 7. Electrons are passed down the chain from one carrier to the next

47. Electron Transport Chain: Oxidation and reduction reactions

48. 8. During the process of electron transport, small amounts of energy are released 9. NADH and FADH2 supply the electrons that move through the electron transport chain 10. Oxygen is the final electron acceptor because it has a very high electronegativity and has a strong attraction for electrons

49. 11. The oxygen with its electrons combines with 2 hydrogens from the surroundings and forms water
Energy lost at each step is used by the cell for phosphorylation to make ATP
Electron transport chain

50. Chemiosmosis: process of making ATP by the movement of protons (H atoms) to provide energy so phosphorylation can occur
1. Oxidative phosphorylation: uses the electron transport chain to make ATP

51. Mitochondria structure is closely related to its function in cellular respiration
a) Matrix: space where the Krebs cycle occurs
b) Cristae: folded interior membranes that holds enzymes and provides a large surface area for electron transport chain and forms a barrier allowing protons to increase on one side

54. ATP synthase: enzyme in the inner membranes that uses the energy of an ion gradient to allow the phosphorylation of ADP to form ATP
a) Ion gradient is created by a difference in hydrogen ion concentration across the cristae membranes
b) H+ are pumped out of the matrix into the intermembrane space and the energy is provided by the electrons moving through the electron transport chain

55. c) More H+ on one side of the membrane creates the gradient
H+ then moves passively through a channel in ATP synthase back into the mitochondrial matrix
As the H+ moves through the ATP synthase, the enzyme harnesses the available energy and allows the phosphorylation of ADP into ATP
ATP synthase

58. Summary of ATP production in cellular respiration
1. Complete catabolism of one molecule of glucose
a) Reactants: glucose and oxygen
b) Many enzymes, carriers, and other molecules used in the process
c) Products: CO2, water, and ATP
2. ATPs are essential because they provide the energy by which life is maintained

59. Three main processes in cellular respiration
Energy flow
Three main processes in cellular respiration
Glycolysis
Krebs cycle
Electron transport chain

60. 36 ATP are produced, but in reality it is closer to 30
a) Some H+ may move back to the matrix without going through ATP synthase
b) Some energy used to move pyruvate into mitochondria
c) About 30% of the energy present in chemical bonds of glucose is generated into ATP and the rest of the energy is lost from the cell as heat

61. Cellular respiration: process by which ATP is provided to the organisms so it can live
a) Complex series of chemical reactions
b) Mostly takes place in mitochondria
c) All organisms need the ability to produce ATP for energy, so all organisms carry out respiration
C6H12O6 + 6O2 6CO2 + 6H2O + ATP

62. Cell Respiration Song