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Food and Energy

Food and Energy. Calorie (kcal). Quantity of heat necessary to raise temp. of 1 L (kg) of H 2 O 1 0 C. kcal = 4.2 kilojoule (kJ). Heat of Combustion. Lipid  9.4 kcal CHO  4.2 kcal Protein  5.65 kcal Net energy value is less. Coefficient of Digestibility (COD). Efficiency of digestion

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Food and Energy

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  1. Food and Energy

  2. Calorie (kcal) • Quantity of heat necessary to raise temp. of 1 L (kg) of H2O 10C. • kcal = 4.2 kilojoule (kJ)

  3. Heat of Combustion • Lipid  9.4 kcal • CHO  4.2 kcal • Protein  5.65 kcal • Net energy value is less

  4. Coefficient of Digestibility (COD) • Efficiency of digestion • % of ingested food utilized for energy • E.g. dietary fiber  COD? • Little difference between obese and lean

  5. Net Energy Values • CHO – 4 kcal/gr • Protein – 4 kcal/gr • Lipid – 9 kcal/gr • Atwater general factors

  6. Atwater General Factors • Used to determine caloric value of food • Composition • Weight

  7. Atwater General Factors ¾ cup of vanilla ice cream (100 grams)

  8. Atwater Factor • Total kcal in 100 grams vanilla ice cream: = (4 g * 4 kcal/g) + (13 g * 9 kcal/g) + (21 * 4 kcal/g) = 217 kcal

  9. Conservation of Energy • Energy is neither created nor destroyed just transformed • Nutrients  chemical energy  mechanical energy  heat energy

  10. Exergonic • Physical or chemical processes that release energy • Potential energy is released

  11. Endergonic • Chemical processes that store or absorb energy • Energy absorbing

  12. Photosynthesis • Endergonic reaction Sun 6 CO2 + 6 H2O 6O2 + C6H12O6

  13. Cellular Respiration • Exergonic reaction 6O2 + C6H12O6 6 CO2 + 6 H2O + ATP

  14. Use of Energy for Work • Mechanical - muscle action • Chemical - synthesis of of molecules for cell growth & maintenance • Transport - active transport

  15. Enzymes • Specific proteins that accelerate chemical reactions (catalysts) • Reduce activation energy • Exercise  enzyme activity

  16. Coenzymes • Non-proteins • Facilitate enzyme activity by helping to bind substrate to specific enzyme • Minerals (Fe, Z), vitamins (B-complex)

  17. Hydrolysis • Catabolism of macronutrients • Exergonic • AB + HOH  A-H + B-OH

  18. Condensation Reactions • H20 is formed • Anabolic process • endergonic

  19. Oxidation and Reduction Reactions • Oxidation – loss of oxygen atoms, hydrogen atoms or electrons • Reduction – gain of oxygen atoms, hydrogen atoms or electrons • Occurs commonly in mitochondria

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