Calculating Calories
Introduction:
Plants have evolved processes that convert light energy into the chemical bonds of complex molecules. The chemical bonds in carbohydrates, lipids and proteins store energy in plants until the energy is needed by the plant. The plant can then release the energy by breaking the appropriate chemical bonds.
Every animal maintains its life processes by consuming complex molecules that store chemical energy. The processed plants and animals we eat as foods contain varying amounts of proteins, carbohydrates, and lipids (all are nutrients). Because each of these foods contain varying amounts of energy, these foods will release varying amounts of energy when they are used by the cells. Within our bodies, the energy is released slowly by a series of chemical reactions.
Background:
When food is burned the chemical energy stored in its molecular bonds is released as heat and light. The heat can be measured in units called calories. A calorie is equal to the amount of heat (energy) required to increase the temperature of one gram of water 1oC. This process is the basis of the technique of calorimetry.
1 Calorie = (4.18 J/g oC) (mass of water in grams) (Tf – Ti )
The more calories a food contains, the more heat (calories) it gives off when burned. Foods high in calories will release large amounts of energy. One gram of a protein will release fewer calories than one gram of lipid because lipids contain more C-H bonds than proteins. You will study foods with different proportions of proteins, lipids, and carbohydrates to see how much energy (calories) they release.
Content videos that connect with the topics presented here can be found at:
Macromolecules
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Reference lab sheet for “Counting Calories - Food Burning Lab” can be found in the attached link: [ Ссылка ]
