The Chemistry of Life 



All living matter in the universe has a chemical structure. To 

 understand living matter more fully it is best to learn something about 

 its chemical nature. All living matter is composed of one basic ma- 

 terial, protoplasm, which has some similarities in all forms of life. 

 Hence, when we learn about the chemical nature of protoplasm in one 

 form of life we have some understanding of the chemical structure of 

 protoplasm in other forms of life. The name protoplasm was first sug- 

 gested in 1840 by a Czech scientist, Purkinje, when he observed this 

 viscid fluid in a wide variety of different kinds of cells. The cells may 

 produce a great variety of products that exist around the protoplasm 

 or as inclusions within the protoplasm, but the actual living part of 

 the cell remains the basic protoplasm. We might expect this proto- 

 plasm to consist of chemical elements which are entirely different from 

 those which form the nonliving materials of the universe, but this is 

 not true. Some of the most common and widely distributed elements 

 of nature, such as carbon, hydrogen, oxygen, and nitrogen, are used in 

 the construction of living matter. 



The Nature of Matter 



Before we can understand the chemical nature of protoplasm we 

 must review a few simple facts of elementary chemistry as a back- 

 ground. Let us start with matter. Matter is anything that has weight 

 and occupies space. It may exist in any one of three states — gas, 

 liquid, or solid — and it may change from one to the other under dif- 

 ferent conditions of temperature or pressure. Water is an example 

 of matter which readily changes its state. Water is a liquid when the 

 air around it is at the pressure found at sea level and its temperature 

 lies between 32°F. and 212°F. Below this range of temperature it 

 forms ice and is a solid. Above this range it forms a gas known as 

 steam. Regardless of the state in which it exists, however, water 

 always has the same chemical composition (H,0.) 



The state in which matter exists depends upon the speed of move- 

 ment of the molecules which compose it. Molecules are in motion in 



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