Bioenergetics

Bioenergetics =energy associated with biological systems. Release, storage, and use of this energy.

75% of diet DM used for energy. Energy is not a nutrient, derived from organic compounds (protein, CHO, fat) in the diet

Energy derived = complete or partial oxidation of organic compounds. These organic compounds absorbed in the GI tract. Energy is in chemical form (stored in bonds - covalent bonds). If animals can break these bonds - they can use this energy released from the breaking of these bonds. Energy may escape!

Trapping energy = Requires systematic breaking of bonds & trapping electrons. Electrons are actually where energy comes from.

e- ® O2 ® H2O and results in energy available for work

Systemic breaking of bonds = required to produce energy - examples: glycolosis, Krebs.

Chemical energy originally from the sun!!

CO2 + H2O + ATP ® glucose (protein, fats, CHO's) All are forms of chemical energy.

So reverse the action to release energy.

Heat = most common form of energy in biochemical reactions because most chemical energy will be converted to heat (INEFFICIENT!!!)

Inefficient metabolism = Body is not 100% efficient, not all ATP energy will be used for work. Heat will escape (given off) = allows for optimum body temperature maintenance

Calorie = the unit of heat measured.

Definition = the amount of heat required to raise the temperature of 1g of H2O 1oC from 14.5 oC to 15.5 oC at 1 atmospheric pressure.

Kilocalorie = 1000 calories

Gross Energy (or caloric density) = Total energy in a compound. Measure with bomb calorimeter

Bomb calorimeter = Pure O2 environment, combust (ignite) = blows up. All chemical energy is converted to heat - measure heat produced and that is caloric density or Gross Energy!

Glucose = 3.75 kcal/g

CHO = 4 kcal/g

Protein = 4 kcal/g

Fat = 9 kcal/g

Alcohol = 7 kcal/g

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