Biol 451-day25

# Biol 451-day25 - Biol 451- Day 25 Reading: Ch.5 *Energy...

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Biol 451- Day 25 Reading: Ch.5 **Energy Metabolism** - is the overall use of chemical energy *-metabolic rate - the measure of the energy metabolism per unit time *-ways to measure metabolic rate total heat production (difficult to do but accurate) (not commonly used) *oxygen consumption - most often used to determine metabolic rate why? its easy to do accurate as long as no anaerobic respiration is occurring **- oxidation of carbs, fat, and protein all produce about the same amount of heat when oxidized per unit of oxygen 4.8kcal/liter O2 - this is fortunate because it means that it doesn’t matter what type of fuel the animal is burning during measurements **BUT!!, each unit mass of food type produces a different amount of heat carbs and protein = 7 kcal/g fat = 9.4 kcal/g that’s why fat is used for energy storage btw- alcohol = 7 kcal/g fat = 2X’s energy of carbs and protein **** If you think about it, the 2 statements above are NOT in conflict with each other!! the 1 st statement means that for the same amount of oxygen, all 3 will produce the same amount of heat. The 2 nd statement means that, regardless of the amount of oxygen used/needed/require, the 3 will produce different amounts of heat per unit mass ***Respiratory Quotient (RQ) CO2 formed / O2 consumed carb RQ = 1.0 fat RQ = 0.71 protein RQ = 0.81 - the RQ is important to know b/c if u know/measure RQ then you know which food is being metabolized during the study unless the RQ is somewhere in b/w these values (b/c then its probably of combination of the 3) the solution is you measure urea/nitrogenous waste of animal measure content of urea and this gives u amount of protein metabolized then you can get carbs and protein from there - if food intake > energy expended energy is stored as fat regardless of what type of food is consumed by the animal why? b/c fat = 9.4 kcal/g ex.) birds beginning migration 50% of body weight = fat (they need a lot of energy)

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**exceptions to fat storage are used and are more efficient when anaerobic respiration is occurring or when body of weigh of animal does not matter (cecile animals) ex.) bivalves they live in areas w/ low O2 content must use anaerobic respiration instead they use glycogen break it down into lactic acid also they’re body weight isn’t important b/c they don’t move -per each gram of glycogen there’s 3-5 grams of H2O stored with it ex.) go on diet use up all ur glycogen so u lose a lot of weight initially b/c the H2O is lost w/ it
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## This note was uploaded on 03/26/2008 for the course BIOL 451 taught by Professor Kier during the Spring '07 term at UNC.

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Biol 451-day25 - Biol 451- Day 25 Reading: Ch.5 *Energy...

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