66 - The Cell 



cases. All the protoplasmic elements are very 

 common in nonliving nature, being abun- 

 dantly represented in the soil, the atmosphere 

 and the waters of the earth. No single ele- 

 ment is entirely peculiar to living things. 

 However, a few — especially carbon and nitro- 

 gen — are relatively much more abundant in 

 living than in nonliving matter. 



BASIC IDEAS AND DEFINITIONS 2 



Matter and Energy. The material compo- 

 nent of our universe — Dialler in general — 

 is to be identified by its universal properties. 

 Always matter occupies space, and always it 

 displays weight. Each kind of matter may 

 assume the form of a solid (like ice), or of a 

 liquid (like water), or of a gas (like water 

 vapor); but whatever its form, matter always 

 retains its identifying attributes. 



Energy is the other fundamental compo- 

 nent of our universe. Energy may take a va- 

 riety of forms, such as light, heat, mechanical 

 movement, electricity, and so forth. In fact 

 energy can only be identified in terms of 

 what it does, or what it can do. Energy is the 

 motion of, or the capacity to produce motion 

 in, any mass of matter. Sometimes the ener- 

 gized mass is very small, as in the case of the 

 flowing electrons of an electric current or 

 the vibrating molecules of a heated substance; 



2 Two kinds of type arc used in this section of the 

 book. For students who have not had chemistry pre- 

 viously, the material in smaller type is just as impor- 

 tant as. if not more important than, the material in 

 larger tvpe. For students who have had chemistry, the 

 material in smaller type will be useful as a review. 



or the material body may be larger, like a 

 bullet hurtling from the barrel of a rifle. 



All forms of energy are at least partially inter- 

 convertible 3 (Table 4-2). This can be illustrated 

 by the electric system of an automobile. The 

 battery of the car contains a store ol chemical 

 energy represented by the reactivity of the acid 

 and other chemicals of the battery. This chemical 

 energy is transformed to electrical energy when- 

 ever the headlight switch is closed, and as the 

 electricity flows through the filament of the lamp 

 bulb, electrical energy is converted to heat. Then 

 when the temperature of the lamp filament 

 reaches the incandescent point, the heat begins 

 to be transformed into light. Or, if the starter 

 switch is pushed and the electricity flows through 

 the starting motor, electrical energy is converted 

 into mechanical energy (the movement of the 

 pistons, etc.) as the engine is forced to "turn over" 

 before it "catches." 



In modern science, everything that happens— 

 every natural event and phenomenon— is to be 

 explained and described in terms of matter and 

 energy, in terms of some change, actual or poten- 

 tial, in the internal or external motion of the 

 components of some material system. Throughout 

 the universe, matter and energy are inseparably 

 associated. Each acts and interacts solely through 

 the medium of the other. Attempting to under- 

 stand the general principles of biology, chemistry. 



3 As predicted by the Einstein equation (e = MC 2 ) 

 matter and energy are also interconvertible. However, 

 such interconversions are insignificantly small except 

 under rare conditions (e.g., in an atomic bomb) and 

 they seem to be unimportant in living organisms. In 

 this equation, the energy (e) is expressed in ergs; the 

 mass (M) is in grams; and the constant (C) represents 

 the velocity of light, expressed in centimeters per sec- 

 ond. 



Table 4-2— Forms of Energy 



Polymolecular* 

 Molecular 



Atomic 



Electronic 

 Radiant 



Kinetic 



Movement (mechanical energy) 



Heat 



Chemical reaction 



Electric current 



Eight, x-rays, etc. 



Potential 



Weight (gravity) 

 Cohesion and adhesionf 

 Chemical reactivity 

 Electric charge 



* Pertaining to masses of visible size. 



+ Cohesion is attraction between molecules of the same substance; adhesion is attraction between molecules 

 of different substances. 



