1. Energy Releasing Pathways ATP

2. Aerobic Respiration A redox process
Glucose contains energy that can be converted to ATP
Uses oxygen therefore aerobic

3. Cellular Energy Transfer
Cells transfer energy by redox reactions
Remember:
oxidation is the loss of electrons
reductions is the gain of electrons
Oxidation involves loss of energy
Reduction involves the gain of energy

5. Aerobic Respiration- Redox
C6H12O6 + 6 O2 + 6 H2O  6 CO H2O + Energy
Water is both a reactant and a product
Glucose is oxidized to form CO2
Oxygen is reduced, forming water
The electrons produced are used to form ATP
oxidation
reduction

6. Aerobic Respiration- 4 Stages
               
               
Glycolysis
Formation of acetyl coenzyme A
Citric Acid Cycle
Electron transport system and chemiosmosis

7. Glycolysis Glucose is converted to 2 3-carbon molecules of pyruvate
ATP and NADH are formed
Occurs in the cytosol
Yellow- products
Green- reactants

8. Glycolysis Pyruvate Yield
Glycolysis means “sugar splitting”
One 6-carbon molecule is converted to two 3-carbon molecules
Occurs in cytosol
Occurs in both aerobic and anaerobic conditions
A series of reactions; each catalyzed by a different enzyme
Glucose yields two pyruvates

11. Glycolysis
First phase requires ATP investment
2 ATPs used
G3P

12. Glucose Fructose- 1,6-diphosphate 2 glyceraldehyde-3-phosphate (G3P)
PHASE 1
Glucose
2 ATPs used
Fructose- 1,6-diphosphate
2 glyceraldehyde-3-phosphate (G3P)

13. Glycolysis
Second phase yields NADH and ATP

14. PHASE 2
G3P
Pyruvate
G3P
Pyruvate
+ 2 NADH
+ 4 ATP

16. Pyruvate to acetyl CoA
A carboxyl group is removed from pyruvate (carbon dioxide is produced)
NADH is produced
acetyl group joins with coenzyme A forming acetyl CoA
Coenzyme A is made from pantothenic acid

17. Pyruvate
Coenzyme A
+ NADH
+ CO2
acetyl CoA

18. Glycolysis
acetyl CoA
Krebs Cycle

20. Acetyl Coenzyme A Pyruvate is converted into acetyl CoA
NADH is produced
Carbon dioxide is a waste product
Occurs in the mitochondria
Yellow- products
Green- reactants

24. 2 pyruvate + 2 NAD+ + 2 CoA ----> 2 acetyl CoA + 2 NADH +
2 carbon dioxide

25. Citric Acid Cycle Oxidizes acetyl CoA Also known as Krebs cycle
Occurs in mitochondria (matrix)
Series of steps ultimately reforming oxaloacetate
All of the energy of glucose is carried by NADH and FADH2

26. Citric Acid Cycle
Acetyl CoA combines with oxaloacetate, forming citrate
Citrate undergoes conversions, ultimately re-forming exaloacetate
Carbon dioxide is a waste product
ATP, NADH, and FADH2 are produced

27. Acetyl CoA
oxaloacetate
+ 6 NADH
+ 2 FADH2
+ 2 ATP

28. One Turn of Citric Acid Cycle*
2C molecule enters the cycle & joins a 4C molecule.
In a series of steps, the remaining H and high energy e- are removed from the 2C.
3 NAD+ are converted into 3 NADH & 3H+.
1 FAD is converted into 1 FADH2.
1 ATP is made.
2 CO2 are released.
At the end of the cycle, nothing remains of the original glucose molecule.
* remember…this is x2!

37. Types of Reactions Dehydrogenation Decarboxylations
Hydrogens are transferred to a coenzyme (NAD+ or FAD)
Decarboxylations
Carboxyl groups are removed from the substrate as carbon dioxide
Preparation reactions
molecules are rearranged in preparation for decarboxylations or dehydrogenations

38. Electron Transport System Chemiosmosis
Electrons that originated in glucose are transferred via NADH and FADH2 to a chain of electron acceptors
Hydrogen ions are pumped across the inner mitochondrial membrane
ATP is produced by chemiosmosis

39. Electron Transport Chain
Coupled to ATP synthesis
Transports e- from NADH and FADH2 to O2
Electrons  FMN  a series of cytochromes and coenzyme Q

40. Electron Carriers Most electron carriers carry hydrogen atoms
Electron carriers transfer energy
Electrons lose energy as they are transferred between acceptors
NAD+ is a common hydrogen acceptor is respiratory and photosynthetic pathways
Nicotinamide adenine dinucleotide

41. Electron Carriers
Nicotine adenine dinucleotide phosphate (NADP+) is involved in photosynthesis

43. NAD+ is a coenzyme derived from the vitamin nicotinic acid (niacin)

44. Electron Carriers
Flavin Adenine Dinucleotide- FAD+ is involved in cellular respiration

46. Electron Carriers
Cytochromes- proteins containing iron

49. Electron Transport Chain
Electrons lose energy as they pass through the chain

50. Electron Transport Chain
Hydrogen ions (protons) are passed into the intermembrane space of the mitochondria

51. Electron Transport Chain
Electrons are finally passed to oxygen thereby forming water

52. NADH
2H+
FMN
Complex I
2H+ Q
FADH2
cyt b
2H+
Complex II
cyt cr
cyt c O2
H2O
cyt a
cyt a3
Complex III

57. Chemiosmotic Model Peter Mitchell
1978 Nobel Prize in Chemistry for a 1961 paper on the chemiosmotic model
Cornwall, UK
Glynn Research Laboratories
Died in 1992
Peter Mitchell

58. Chemiosmotic model
Explains the coupling of ATP synthesis to electron transport
A proton gradient is formed across the inner mitochondrial membrane

59. Chemiosmotic Model
Protons diffuse through the channels formed by the enzyme complex ATP synthase
Movement of protons catalyze production of ATP

61. http://telstar. ote. cmu. edu/biology/animation/ATPSynthesis/biochem

63. Energy Yield Efficiency is about 40%; the rest is disseminated as heat
Maximum yield of ATPs
from NADH- 3 ATP
from FADH2- 2 ATP
The NADHs from glycolysis produce fewer ATPs due to the necessity of transport of NADH across the mitochondrial membrane

64. Energy Yield
The NADHs from glycolysis produce fewer ATPs due to the necessity of transport of NADH across the mitochondrial membrane
36 to 38 ATPs yield

65. ATP produced
GLUCOSE

66. 2 ATP
GLUCOSE
2 ATP
produced directly
GLYCOLYSIS

67. 38 ATP 16 ATP 34 ATP 8 ATP 14 ATP 2 ATP 2 NADH 2 NADH 6 NADH 2 FADH2
GLUCOSE
2 ATP
produced directly
GLYCOLYSIS
6 ATP
through electron transport +
2 NADH
PYRUVIC ACID
6 ATP
through electron transport +
2 NADH
2 ATP
produced directly +
ACETYL CoA
18 ATP
through electron transport +
KREBS CYCLE
6 NADH
4 ATP
through electron transport +
2 FADH2

68. Other Nutrients Nutrients other that glucose provide energy
Humans gain more energy from oxidation of fatty acids than glucose
Lipids contain 9 kcal per gram
Lipids are broken down and glycerol enters glycolysis; fatty acids are converted to acetyl CoA and enter the citric acid cycle

69. Other Nutrients Proteins are broken down into amino acids
Amino acids are deaminated (the amino acids are removed)
The remaining carbon chain centers at various points
Proteins contain about 4 kcal per gram

70. Regulation of Aerobic Respiration
ATP synthesis continues until ADP stores are depleted
Enzyme regulation is important
An important regulation point is phosphofructokinase

71. PFK is activated by ADP/AMP
PFK is the committed step in glycolysis. Once this step is done then glycolysis will carry through.
PFK is inhibited by
ATP
low pH
citrate groups
PFK is activated by ADP/AMP

72. Anaerobic Respiration
Various inorganic substances serve as the final electron acceptor like sulfur
Yield is only the two ATP molecules from glycolysis
Seen is some bacteria

73. Alcoholic Fermentation
Produces ethanol
Pyruvate is converted to ethanol to regenerate NAD+
Ethanol is a potentially toxic waste product
Yeast carry out alcoholic fermentation when oxygen deprived

75. Lactate Fermentation
Bacteria and some fungi carry out lactate fermentation
Pyruvate is converted to lactate to regenerate NAD+
Strenuous exercise in mammals results in lactate fermentation as well

78. Must Know...

79. http://micro. magnet. fsu