Transcript Slide 1
Metabolism
Chapter 7 Metabolism: FON 241; L. Zienkewicz
Metabolism:
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Metabolism: refers to the entire network of chemical processes involved in maintaining life.
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Energy metabolism: the ways that the body obtains and spends energy from food.
Metabolism: FON 241; L. Zienkewicz
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Anabolism: The building of compounds from small molecules into larger ones
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Energy is used for this process to take place.
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Catabolism
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The breakdown of molecules into smaller units. Energy is released in this process.
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Ex: Glucose catabolism results in the release of CO 2 and H 2 O Metabolism: FON 241; L. Zienkewicz
ATP (Adenosine Triphosphate):
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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:
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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.
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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:
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The site for metabolic activity.
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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:
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Enzymes: proteins that facilitate chemical reactions without being changed in the process; protein catalysts.
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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 Carbohydrates Common Pathway Energy 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 Less oxygen available Pyruvate 2 ATP Oxygen available Lactic Acid Acetyl CoA Metabolism: FON 241; L. Zienkewicz
The path from Pyruvate to Acetyl CoA is NOT reversible.
Metabolism: FON 241; L. Zienkewicz
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.)
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Deamination: AA
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Transamination Keto acid and Ammonia
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Ammonia Urea in the Liver
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Urea excreted via the kidneys
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Water needed for urea excretion Metabolism: FON 241; L. Zienkewicz
The TCA Cycle:
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Functions to convert Acetyl CoA to CO 2 and to produce energy.
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Oxaloacetate combines with Acetyl CoA to begin the cycle.
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The result: produces potential ATP (energy).
Metabolism: FON 241; L. Zienkewicz
The Electron Transport Chain:
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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?
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Fat’s carbon-hydrogen bonds can be easily oxidized, yielding energy (ATP).
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1 glucose molecule yields 38 ATP when oxidized.
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1 fatty-acid (16-C) will yield 129 ATP when oxidized.
Metabolism: FON 241; L. Zienkewicz
Weight Maintenance:
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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.
Metabolism: FON 241; L. Zienkewicz