Metabolism: FON 241; L. Zienkewicz Metabolism Chapter 7

Metabolism: FON 241; L. Zienkewicz Metabolism: Metabolism: refers to the entire network of chemical processes involved in maintaining life. Energy metabolism: the ways that the body obtains and spends energy from food.

Metabolism: FON 241; L. Zienkewicz Anabolism: The building of compounds from small molecules into larger ones. Energy is used for this process to take place. Catabolism: The breakdown of molecules into smaller units. Energy is released in this process. –Ex: Glucose catabolism results in the release of CO 2 and H 2 O

Metabolism: FON 241; L. Zienkewicz ATP (Adenosine Triphosphate): The main energy source of cells. Used for muscular contractions, enzyme activity, etc. Catabolism results in the production of many ATP molecules: energy. Used by the body when energy is needed. Hydrolysis breaks the bonds in ATP, thus releasing energy.

Metabolism: FON 241; L. Zienkewicz Metabolic Efficiency: Food energy is converted to ATP with approximately 50% efficiency. The other 50% is released as heat. When ATP is needed for energy, ~50% are used. Overall: 25% of food becomes energy 75% is released as heat.

Metabolism: FON 241; L. Zienkewicz The Cell: Q: Approximately how many cells does the human body contain? A: 1x10 14 cells or 100,000,000,000,000. (100 trillion cells)

Metabolism: FON 241; L. Zienkewicz The Cell: The site for metabolic activity. Liver cells are the most metabolically active.

Metabolism: FON 241; L. Zienkewicz How is energy produced? Three stages: 1. Proteins, Carbohydrates and Fats are broken down during digestion and absorption into smaller units: AA’s monosaccharides and fatty acids. 2. These smaller compounds are further broken down into 2-carbon compounds. 3. Compounds are degraded into CO 2 and H 2 0.

Metabolism: FON 241; L. Zienkewicz Helpers in reactions: Enzymes: proteins that facilitate chemical reactions without being changed in the process; protein catalysts. Coenzymes: assist enzymes in their activities.

Metabolism: FON 241; L. Zienkewicz Breakdown of nutrients for energy: 1.Glucose breakdown 2.Glycerol and Fatty Acid breakdown 3.Amino Acid breakdown Common Pathway Energy Fats Carbohydrates Protein

Metabolism: FON 241; L. Zienkewicz 1. Glucose breakdown Glycolysis: A reaction in which glucose is degraded to pyruvate; net profit: 2 ATP. An anaerobic pathway. Glucose Pyruvate Lactic Acid Acetyl CoA Oxygen available 2 ATP Less oxygen available

Metabolism: FON 241; L. Zienkewicz The path from Pyruvate to Acetyl CoA is NOT reversible.

Metabolism: FON 241; L. Zienkewicz

2. Glycerol and Fatty Acid breakdown Triglycerides are broken into: Glycerol and Fatty Acids (lipolysis). Glucose Glycerol Pyruvate Fatty acids Acetyl CoA

Metabolism: FON 241; L. Zienkewicz 3. Amino Acid breakdown Glucose Amino Acids Pyruvate Amino Acids Acetyl CoA Amino Acids TCA Cycle

Metabolism: FON 241; L. Zienkewicz 3. Amino Acid breakdown (cont.) Deamination: AA Keto acid and Ammonia Transamination Ammonia Urea in the Liver Urea excreted via the kidneys Water needed for urea excretion

Metabolism: FON 241; L. Zienkewicz The TCA Cycle: Functions to convert Acetyl CoA to CO 2 and to produce energy. Oxaloacetate combines with Acetyl CoA to begin the cycle. The result: produces potential ATP (energy).

Metabolism: FON 241; L. Zienkewicz The Electron Transport Chain: The primary site for ATP (energy) synthesis. Uses Oxygen to convert products of the TCA cycle into energy.

Metabolism: FON 241; L. Zienkewicz Why is fat higher in energy? Fat’s carbon-hydrogen bonds can be easily oxidized, yielding energy (ATP). 1 glucose molecule yields 38 ATP when oxidized. 1 fatty-acid (16-C) will yield 129 ATP when oxidized.

Metabolism: FON 241; L. Zienkewicz Weight Maintenance: Dietary fat can be easily transformed into body fat. Surplus protein leads to: 1. Replacing daily losses. 2. Increased protein oxidation (energy). 3. Storage as fat. Surplus carbohydrate leads to: 1. Storage as glycogen. 2. Increased CHO oxidation (variable w/ diet). 3. Storage as fat.

Metabolism: FON 241; L. Zienkewicz The body’s #1 priority: 1.Meet its energy needs.