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Chemistry of Life
At this very second, thousands of chemical reactions are taking place in your body. Various constituents of the body are joining together or being split apart or undergoing intricate exchanges and rearrangements. The sum total of all the chemical reactions that go on in the living organism is called metabolism1. Some of these reactions result in a build up of body structure; they form the category of anabolic reactions. Catabolic reactions, on the other hand, are the breakdown reactions of the body. Both go on constantly in a bewildering interplay that is life.
Chemical Constituents of the Body
The substance of life, protoplasm is a complex mixure of inorganic and organic compounds. None of its elements is unique to living things. owever, the distribution of the elements in the living and non-living worlds is quite different. And even more important is that the element in living organisms are confined into an assortment of complex compounds, many of which have no counterpart in the nonliving world. The main constituents of protoplasm are : water, inorganic salts, proteins, carbohydrates, lipids (fats and nucleic acids.
Water Water is the most abundant compound in the body, constituting more than 65 percent of the total body weight. It is one of the simplest compounds yet one of the most imortant. A human being can survive for only a few days without taking water.
1. Discussed in detail in chapter No. IV of this book.
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