1. Metabolism
Metabolism – all chemical reactions necessary to maintain life.
Anabolic reactions – synthesis of larger molecules from smaller ones. (dehydration synthesis)
Catabolic reactions –(hydrolysis) of complex structures into simpler ones.
Cellular respiration – food is broken down within cells to their basic organic building blocks.
The energy captured from the food is used to produce ATP

2. Cellular Energy
All cells require a constant supply of ATP. It is essentially the currency that all cells use for energy. Without a constant supply the cell will die.
Specific proteins in the cell are capable of hydrolyzing ATP ATP ADP + P (energy released for reactions)
ATPase
ADP(adenosine diphosphate) and a phosphate group synthesize ATP by creating high energy bond between the 2nd and 3rd phosphate group
ADP + P ATP ( energy storing)
The energy from eating organic compounds provide the energy to create ATP

3. Cellular Energy
The energy stored in the phosphate bonds of ATP originally comes from the plants ability to capture radiant energy from the sun. This allows the plants to convert inorganic molecules into organic molecules. This process called photosynthesis.
Radiant energy
6H2O + 6CO ATP  C6H12O6 + 6O ADP +36 P
The energy is stored within the H’s of organic molecules (monosaccharides, fatty acids and amino acids).
We eat the plants and animals that eat the plants. Our cells can extract the energy stored within the H’s and produce ATP
The more H’s food has the more energy it contains.

4. Energy Metabolism
During cellular respiration the energy stored in a glucose’s H are removed and taking to a specific part to the cell to harness the energy and make ATP. Several B vitamins are required for this process.
2 B-vitamin derivatives coenzymes NAD (niacin) and FAD (Riboflavin) are required for oxidation-reduction reactions to remove the hydrogen.
These enzymes oxidizes sugar intermediates
(loss of an electron/hydrogen atom)
NAD NADH reduced
(gain of an electron/hydrogen atom)
FAD FADH2 reduced
the reduced coenzymes are taken to the cristea of mitochondria where 32 of the 36 ATP’s are formed.

5. Cellular Respiration

6. 7

7. C6H12O6 + 6O2  6H2O + 6CO2 + 36 ATP + heat
Cellular Respiration
Since all carbohydrates are transformed into glucose, it is essentially glucose metabolism
Oxidation of glucose is shown by the overall reaction:
C6H12O6 + 6O2  6H2O + 6CO ATP + heat
Glucose is oxidized in three pathways
Glycolysis (cytoplasm) =sugar/lyses (splitting)
Krebs cycle (matrix of mitochondria)
The electron transport chain (cristae of mitochondria)

8. Glycolysis: Phase 1 and 2 Phase 1: Sugar activation
Two ATP molecules are hydrolyzed providing the energy required to start Glycolysis
Glucose is into converted into fructose-1,6-diphosphate after 2 hydrolyzed phosphates for each ATP attach to the Glucose.
Phase 2: Sugar cleavage
Fructose-1,6-bisphosphate is cleaved into two 3-carbon isomers
Bishydroxyacetone phosphate( gets converted to G3P)
Glyceraldehyde 3-phosphate ( G3P) Also known as Phosphglyceraldahyde

9. Glycolysis: Phase 3 Phase 3: Oxidation and ATP formation
The 3-carbon sugars are oxidized (reducing NAD+ forming NADH)
Inorganic phosphate groups (Pi) are attached to each oxidized fragment
The terminal phosphates are cleaved and captured by ADP to form four ATP molecules by substrate level phosphorylation.

10. Glycolysis: Phase 3 The final products are: Two pyruvic acid molecules
Two NADH molecules (reduced NAD+)
A net gain of two ATP molecules

11. Glycolysis Overview A three-phase pathway in which: Pyruvic acid:
Glucose is oxidized into pyruvic acid
NAD+ is reduced to NADH
2 ATP is synthesized by substrate-level phosphorylation
Pyruvic acid:
Moves on to the Krebs cycle in an aerobic pathway
Is reduced to lactic acid in an anaerobic environment

12. 9

13. Intermediate Step For Krebs Cycle
Occurs in the mitochondria and is fueled by pyruvic acid
If there is enough O2 present pyruvic acid is converted to acetyl CoA in three main steps:
Oxidation
Hydrogen atoms are removed from pyruvic acid
NAD+ is reduced to NADH
Decarboxylation
Carbon is removed from pyruvic acid in the form of Carbon dioxide forming acetic acid
acetic acid is combined with coenzyme A to form acetyl CoA

14. Pyruvic Acid → Acetyl CoA
During this step the products are:
2 molecules of CO2
2 molecules of NADH
2 molecules of Acetyl CoA

15. Krebs Cycle

16. End Products of Krebs Cycle
2 acetyl CoA entering the Krebs Cycle will yield:
6 NADH and 2 FADH2 shuttles H to electron transport chain located on the cristea.
ATP will be produced by oxidative phosphorylation
4 CO2
2 ATP via substrate level Phosphorylation.

17. Electron Transport Chain

18. Electron Transport Chain (ETC)
The NADH and FADH2 from glycolysis, acetyl CoA formation and the Krebs cycle are shuttled to the cristea (inner membrane of the mitochondria)
The cristea has 3 integral membrane proteins that pump protons into the intermembrane space from the matrix. This creates a proton gradient.
NADH drops a pair of electrons (e-) at the first protein complex while FADH2 goes to the second complex.
The oxidation of NADH and FADH2 back to NAD and FAD enables these co-enzymes to travel back to the cytoplasm and mitochondria to oxidize another sugar molecule.

19. Electron Transport Chain
The e- energize the first protein complex results in 2 protons (H+) from the matrix to be pumped into the intermembrane space.
The e- are shuttled from the first protein complex to the second one by Co-enzyme Q10
2 more protons get pumped out into the intermembrane space.
Cytochrome (Cyt c) moves the e- to the final protein complex
This creates a high H+ concentration in the intermembrane space

20. ATP Synthase.
The H+ diffuse along their concentration gradient back into the matrix through the channel protein ATP synthase.
As the H+ go through the ATP synthase complex energy is created to phosphorylate ADP to make ATP
(Oxidative Phosphorylation) ATP produced way
In order to ensure a H+ gradient O2 must be present in the mitochondria.
The electrons are transferred to the O2 at the last enzyme complex making O2 especially negative
O2- atom combined with the H+ that have diffused back into the matrix from the intermembrane space to form water (H2O)
O2 must work as the final electron acceptor in the ETC

21. Lactic Acid Fermentation
If there is not enough O2 present in the Mitochondria the NADH will return to the cytosol and reduce pyruvic acid to form Lactic acid.
Lactic acid is another source for ATP
Lactic acid will be oxidized back to pyruvic acid once O2 is present again

22. Clinical Connection There are several forms of Anemia.
Iron deficiency is one of the most common types
Iron is critical for O2 carrying hemoglobin
Iron is also vital for transferring electrons along the chain.
Symptoms include SOB, fatigue, weakness and unusual food cravings ( pica)
More common in the elderly
Vitamin C aids in the absorption of iron
Iron is important for energy production!

23. Glycogen Metabolism
ATP is quickly used after it is formed -- it is not a storage molecule
extra glucose will not be oxidized, it will be stored
Glycogenesis -- synthesis of glycogen
stimulated by insulin (average adult contains 450 g) primarily the liver and Type II muscle fibers.)
Glycogenolysis -- glycogen  glucose
stimulated by glucagon and epinephrine
only liver cells can release glucose back into blood
Gluconeogenesis -- synthesis of glucose from non-carbohydrates, such as Lactic acid, pyruvic acid, glycerol and amino acids
Takes place mainly in the liver.
Protects the body, especially the brain, from the damaging effects of hypoglycemia by ensuring ATP synthesis can continue

24. Lipids Triglycerides are stored in adipocytes
constant turnover of molecules every 3 weeks
released into blood, transported and either oxidized or redeposited in other fat cells
Lipogenesis = synthesizing fat from other sources
amino acids and sugars used to make fatty acids and glycerol
Lipolysis = breaking down fat for fuel
glycerol is converted to PGAL and enters glycolysis
fatty acids are broken down 2 carbons at a time to produce acetyl-CoA (beta oxidation)

25. Lipid Metabolism Glycerol is converted to glyceraldehyde phosphate
Glyceraldehyde is ultimately converted into acetyl CoA
Acetyl CoA enters the Krebs cycle
Fatty acids undergo beta oxidation which produces:
Two-carbon acetic acid fragments, which enter the Krebs cycle
A 24 carbon fatty acid can produce 12 acetic acids.
36 total NADH and 12 FADH2 = 120 ATP compared to 32 from glucose
Fats are the best fuel source

26. Lipid Metabolism

27. Lipogenesis and Lipolysis
Excess dietary glycerol and fatty acids undergo lipogenesis to form triglycerides.
Elevated triglycerides is a major cardiac risk factor.
Lipolysis, the breakdown of stored fat, is essentially lipogenesis in reverse
Oxaloacetic acid is necessary for the complete oxidation of fat
Fat will only burn in a carbohydrate flame!
Without Carbs fatty acid oxidation is shut down.
Acetyl CoA is converted into ketones (ketogenesis)

28. Ketogenesis
Fatty acids catabolized into acetyl groups (by beta-oxidation in mitochondrial matrix) may
enter citric acid cycle as acetyl-CoA if sugar is present
undergo ketogenesis is the absence if carbohydrates
metabolized by liver to produce ketone bodies
acetoacetic acid
-hydroxybutyric acid
acetone
rapid or incomplete oxidization of fats raises blood ketone levels (ketosis) and may lead to a pH imbalance (ketoacidosis)
pH changes can denature many enzymes.
This is very common in uncontrolled diabetics and people on no carb diets.

29. Lipogenesis and Lipolysis Pathways

30. Proteins
Amino acid pool - dietary amino acids plus 100 g of tissue protein broken down each day into free amino acids
May be used to synthesize new proteins
As fuel – Only as a last resort
first must be deaminated (removal of NH2)--what remains is converted to pyruvic acid, acetyl-CoA or part of citric acid cycle
High protein diets are popular because you may experience rapid weight loss. This is the result of your kidneys pulling more water out of your body to get rite of the excessive nitrogenous wastes

31. Pathways of Amino Acid Metabolism