Renascent Systems, teaching about NADH - Life's Energy Source
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How Energy is
stored in the Body . . . to the previous page  Glycogen is stored all over the body. There are large
deposits of glycogen in the liver, in the muscles, and in the kidneys. As the body needs
glucose, glycogen is broken down into glucose molecules to supply the body's immediate
needs. If there is any excess glucose in the blood, as there is after a meal, it is
shipped to the glycogen storage depots. When energy is needed, glucose molecules are broken down to release energy in the form of heat. The release of energy takes place in an astounding series of reactions brought about within the body by chemical substances known as enzymes and coenzymes. The earliest glimpses of these reactions were obtained, oddly enough, from studies of yeast cells, not of animals. Yeast cells, up to a point, use sugars for their energy exactly as we do. Before we can be qualified as engineers for the human body, this most marvelous of machines, we need to know how energy is released in chemical reactions. All forms of energy are interchangeable. That is, heat can be changed into motion; motion can be changed into electricity, which, in turn, can give light or heat again. Such conversions or changes are often very wasteful. The average steam locomotive loses over 90 percent of the energy of the steam as it converts the remaining 10 percent to motion. The average light bulb uses 90 percent of its energy in creating heat, the rest of the energy is used to produce light. |
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green plants  |
How Energy is released Energy cannot be destroyed. We can take a pound of coal and burn it in an ample supply of air while it changes to carbon dioxide. An amount of heat (n) will be given off. If we burn another pound of coal in a limited supply of air it will form carbon monoxide, but only about one-fourth (1/4) as much heat will be liberated as before. If we now burn all of this carbon monoxide to carbon dioxide, we get the rest of the original amount of heat (n). Whether we release the energy in one step or in several steps, the overall amount is the same. What about the energy in glucose? Measurements of energy are always based on the chemist's unit weight, or molecular weight. Glucose weighs 180 grams. (One molecule of glucose weighs 180 times as much as one atom of hydrogen.) When a green plant makes glucose from carbon dioxide and water, it packs energy into it. Into about 180 grams (or six ounces) of glucose are packed 700 calories of energy. The calorie is a measure of heat energy. One hundred calories will heat one liter (about a quart) of ice-cold water to boiling. If we burn the 180 grams of glucose, 700 calories of heat will be released. Where are these 700 calories hidden? They are used to form the bonds that hold together the six carbon atoms, the twelve hydrogen atoms, and the six oxygen atoms that make up the one glucose molecule. There is energy in chemical bonds. (1 glucose = C6H12O6) Imagine a dozen large springs from a mattress squeezed into a hatbox. A good deal of energy had to be used to squeeze the springs together before the box lid could be safely locked. If the lid is opened, the jumping springs will release the same amount of energy that was used to put them into the box. This is a fair comparison of the energy used to lash the atoms of carbon, hydrogen, and oxygen together to form glucose. (This bond energy has nothing to do with the energy within the nucleus of the atom, known as atomic energy. And, of course, bond energy is not nearly so great as the monstrous energy of the nucleus.) . . . continued on the next page |
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©1996-2008_Renascent_Systems_Inc_All_rights_reserved_Rev01/2008 |