1. Metabolic Reactions and Energy Transfer
Learning Outcome 26: Define metabolism.

2. Metabolism The sum of catabolism and anabolism
Catabolism - decomposition reactions that break down molecules and release energy.
Heat, light, sound
Anabolism - synthesis reactions that build molecules and require energy.
Make chemical bonds
DNA

3. Metabolic Reactions
Learning Outcome: 27: Explain the role of ATP in anabolism and catabolism.

4. Coupling of Catabolism and Anabolism by ATP
ATP couples energy-releasing reactions to energy- requiring reactions.
Catabolism - some of the energy (approx. 40%) is transferred to ATP; the rest is given off as heat.
Anabolism - ATP provides the energy for synthesis; some energy is given off as heat.

5. Figure 25.1 Role of ATP in linking anabolic and catabolic reactions.

6. Energy Transfer
Learning Outcome 28: Describe oxidation- reduction reactions.

7. Oxidation – Reduction Reactions
Oxidation (OIL)
The removal of electrons from a molecule.
Results in a decrease in the energy content of the molecule.
Most biological examples are dehydrogenation reactions.
Ex: Lactic acid  Pyruvic acid + 2H
2H is in the form H+ + H-
Dehydrogenation – loss of hydrogen atoms
2 neutral hydrogen atoms are removed as one hydrogen ion (H+) and one hydride ion (H-)
Page 942 in textbook

8. Oxidation – Reduction Reactions
Reduction (RIG)
The addition of electrons to a molecule.
It results in an increase in the energy content of the molecule.
Example: Pyruvic acid + 2H  Lactic acid.
LDH = lactate dehydrogenase
NADH is a coenzyme found in all living cells. It stands for nicotinamide adenine dinucleotide hydride. It is a dinucleotide (2 nucleotides joined through their phosphate groups)
Coenzyme = enhances the work of enzymes in the body
The H stands for the high energy hydrogen  meaning it is a biologically active state
When the body is deficient in NADH, it is kind of like a car that has run out of gasoline. 
The production of NADH declines as we age

9. Lactic Acid Cycle
Lactic acid diffuses from the muscles and is transported through the bloodstream to oxygen-rich tissues such as the heart and liver, where it is catabolized further through the lactic acid cycle or converted to glucose via gluconeogenesis. Even in fully oxygenated muscle tissue, as much as 50% of the metabolized glucose is converted to lactic acid by way of pyruvic acid
If you exercise strenuously without sufficient oxygen, lactic acid accumulates and contributes to muscle fatigue and soreness. When oxygen is later available, lactic acid must be oxidized to pyruvic acid.

10. Oxidation – Reduction Reactions
Oxidation and reduction reactions are always coupled.
Such paired reactions are called redox reactions.
Oxidation reactions are usually exergonic.
Aided by coenzymes
Oxidation is loss
Reduction is gain

11. Redox Coenzymes
When a substance is oxidized, the 2H atoms released are used to reduce another substance.
Two coenzymes that carry 2H atoms from an oxidation reaction to a reduction reaction are:
Nicotinamide adenine dinucleotide (NAD)
Flavin adenine dinucleotide (FAD)
NAD is derived from vitamin B (niacin)
FAD is derived from vitamin B2 (riboflavin)

12. NAD Reduction Malic Acid Oxaloacetic Acid H+ + H- NAD+ NADH + H+
reduced
oxidized
NADH is a coenzyme found in all living cells. It stands for nicotinamide adenine dinucleotide hydride. It is a dinucleotide (2 nucleotides joined through their phosphate groups)
Coenzyme = enhances the work of enzymes in the body
The H stands for the high energy hydrogen  meaning it is a biologically active state
When the body is deficient in NADH, it is kind of like a car that has run out of gasoline. 
The production of NADH declines as we age
The addition of a hydride ion neutralizes the charge

13. NADH + H+ Oxidation Pyruvic Acid Lactic Acid H+ + H- NAD+ NADH + H+
reduced
H+ + H-
NAD+
NADH + H+
oxidized

14. FAD Reduction Succinic Acid Fumaric Acid H+ + H- FAD FADH2 oxidized
reduced
oxidized

15. FADH2 Oxidation Fumaric Acid Succinic Acid H+ + H- FAD FADH2 oxidized
reduced
H+ + H-
FAD
FADH2
oxidized

16. Energy Transfer
Learning Outcome 29: Describe three mechanisms of ATP generation.

17. Three Mechanisms of ATP Generation
Substrate-level phosphorylation
Generate ATP directly by transferring a phosphate group to ADP.
Oxidative phosphorylation
Generate ATP indirectly by transporting electrons from oxidized substances to the electron transport chain.
Photophosphorylation
Generate ATP from light energy.

18. Carbohydrate Metabolism
Learning Outcome 30: Describe the mechanism of glucose movement into body cells.

19. Glucose Movement into Cells
In digestive tract, polysaccharides  monosaccharides.
80% glucose, 20% fructose and galactose
Absorption through epithelial cells of the intestine converts some fructose into glucose
Absorbed monosaccharides are transported to the liver
Liver hepatocytes convert other monosaccharides to glucose.
So…carbohydrate metabolism = glucose metabolism

20. Glucose Movement into Cells
Glucose must pass PM into cytosol before cells can use it.
Absorption via Na+ - glucose symporters
Insulin Dependent GluT molecules
Secondary active transport
In GI tract and kidneys
Family of facilitated diffusion transporters
Most other body cells

21. Glucose Movement into Cells
Normal blood glucose = 90 mg/100 ml of plasma.
Controlled by negative feedback
Approx 2-3g of glucose circulates in your blood

22. Carbohydrate Metabolism
Learning Outcome 31: Describe glucose catabolism.

23. Fates of Glucose ATP production Amino acid synthesis
When body cells need immediate energy glucose is oxidized  ATP
Amino acid synthesis
Glucose can be used to form a.a. and then proteins
Glycogen synthesis
Hepatocytes and muscle fibers = glycogenesis
Formation of glycogen (hundreds of glucose monomers)
Triglyceride synthesis
When glycogen stores are filled
Hepatocytes convert glucose  glycerol and fatty acids for lipogenesis
Triglycerides stored in adipose tissue

24. Glucose Catabolism AKA cellular respiration.
Provides the cell’s chief source of energy.
Occurs in four successive stages:
Glycolysis
Formation of acetyl coenzyme A
The Krebs cycle
The electron transport chain
heat
36 or 38 ATP
C6H12O6 + 6O2
6H2O + 6CO2

25. Oxidation of Glucose
heat
36 or 38 ATP
C6H12O6 + 6O2
6H2O + 6CO2

26. Figure 25.2 Overview of cellular respiration (oxidation of glucose).

27. Glycolysis The first stage of glucose catabolism.
Occurs in the cytosol
Does not require oxygen (anaerobic reaction).
Converts 1 glucose (6 carbons) into two pyruvic acid (3 carbons each).
Energy molecules produced:
2 ATP
2 NADH

28. Figure 25.3 Cellular respiration begins with glycolysis

29. Figure 25.4 The 10 reactions of glycolysis

30. Summary of Glycolysis Where does this happen? What are the reactants?
Cytosol
What are the reactants?
Glucose
What are the products?
2 (3C) pyruvic acids
How much $?
2 ATP
2 NADH

31. The Fate of Pyruvic Acid
Dependent on oxygen availability:
When oxygen is in short supply, pyruvic acid is reduced to lactic acid.
Ex. During strenuous exercise in skeletal muscle fibers – build up causes muscle fatigue.
When oxygen is plentiful, most cells convert pyruvic acid to acetyl coenzyme A.

32. Oxygen Requirements Summary
Glycolysis has no O2 requirement – aerobic or anaerobic conditions
Aerobic respiration is Krebs cycle and electron transport chain – both require O2
All 4 stages of glucose catabolism only occur when O2 is present
When there is little to no O2 then pyruvic acid is converted into lactic acid and cellular respiration halts.

33. Figure 25.5 Fate of pyruvic acid
Because RBC lack mitochondria, they can only produce ATP through glycolysis

34. Formation of Acetyl Coenzyme A
Each step in oxidation of glucose requires a different enzyme and often coenzyme
Acetyl Coenzyme A connects glycolysis (cytosol) to Krebs cycle (mitochondria)

35. Formation of Acetyl Coenzyme A
Occurs in the mitochondrial matrix
Pyruvic acid (3C)  acetyl group (2C).
The carbon is lost as CO2 (decarboxylation).
Coenzyme A is added to the acetyl group to form acetyl CoA
NAD+ is reduced to NADH

36. Figure 25.5 Summary of Acetyl CoA Formation
Reactants:
2 pyruvic acids
2 coenzyme A
Products
2 acetyl CoA
2 CO2
2NADH

37. Krebs Cycle Also called the citric acid cycle
First molecule formed when an acetyl group joins
Step-by-step release of energy stored in acetyl CoA
Involves decarboxylations and redox reactions
Occurs in the mitochondrial matrix
Each time an acetyl CoA enters the cycle, it undergoes one complete “turn”
Starts by forming citric acid and ends by forming oxaloacetic acid

38. Figure 25.6 After formation of acetyl coenzyme A...

39. Krebs Cycle
Each time an acetyl CoA enters the cycle, it undergoes one complete “turn”
Starts by forming citric acid and ends by forming oxaloacetic acid
Products for each turn:
3 NADH
3 H+
1 FADH2
1 ATP – substrate-level phosphorylation
2 CO2 – decarboxylation
Each glucose molec provides 2 acetyl CoA = 2 turns
redox reactions

40. Figure 25.7 The eight reactions of the Kreb’s cycle.
Summary of Kreb’s Cycle
Reactants:
2 acetyl CoA
Products
4 CO2
2 ATP
6 NADH
2 FADH2

41. The Electron Transport Chain
A sequence of electron carrier molecules
Integral membrane proteins
On the inner mitochondrial membrane (cristae)
Capable of a series of redox reactions
The last electron receptor of the chain is O2
Energy stored in NADH
and FADH2 is used to
pump H+ from the matrix
into the space between
the inner and outer membranes.

42. Chemiosmosis produces ATP
Links chemical reactions with pumping H ions.
H+ ions are allowed to diffuse back into the matrix (chemiosmosis)
H+ channels are coupled with ATP synthase
1 NADH  3 ATP molecules
1 FADH2  2 ATP molecules

43. Figure Chemiosmosis

44. Figure 25.9 Electron Transport Chain Details
Each pump = complex of 3+ electron carriers

45. Summary of Aerobic Cellular Respiration
The complete oxidation of one glucose molecule can be represented as follows:
C6H12O6 + 6O2  36 or 38ATP + 6CO2 +6H2O

46. Figure 25.10 Summary of Cellular Respiration

47. Summary of Glucose Oxidation
Glycolysis
2 pyruvic acids
2 ATP (substrate-level phosphorylation)
2 NADH + 2 H+
6 ATP (electron transport chain)
Acetyl Co A synthesis
2 NADH + 2H+
Krebs Cycle
2 GTP
6 NADH + 6 H+
18 ATP (electron transport chain)
2 FADH2
4 ATP (electron transport chain)
Total
38 ATP (theoretical maximum); probably closer to 36 ATP

48. Assigned Reading Outcomes 7-10 Pages 8-11 in notes
Focus on understanding the bolded terms (I encourage you to highlight them in NOTES)
Know the definitions not the cycles
Know which type of metabolism they fall under
Ex. Glycogenesis, glycogenolysis, gluconeogenesis, lipoproteins, chylomicrons, VLDLs, LDLs, HDLs, lipolysis, beta oxidation, lipogenesis