542 



COLLEGE ZOOLOGY 



bine with other compounds to form proto- 

 plasm, or they may be oxidized to furnish 

 energy for the cells; this oxidation occurs 

 at a relatively low temperature, due to the 

 activity of enzymes within the cells. Certain 

 amounts of glucose are converted in the 

 liver and muscles into glycogen, which is 

 often called animal starch. Stored glycogen 

 can be reconverted into glucose and utilized 

 when needed between meals. 



Fats 



Fats and fatlike bodies may be built up 

 into the protoplasm of cells; they are es- 

 pecially abundant in cell membranes and 

 are largely responsible for the semipermeabil- 

 ity of these membranes. They may be 

 stored in special fat cells that are scattered 

 throughout the body. When insufficient 

 food is taken into the body, these fat reser- 

 voirs are utilized for production of energy 

 and heat, a process that requires more time 

 than is the case with glycogen. An example 

 of a chemical equation involving oxidation 

 of a typical fat (tripalmitin) into carbon 

 dioxide and water with the liberation of 

 energy is as follows: 



Carbon dioxide 

 ^ lOZCOa + 



Fat Oxygen 



ZCeiHseOe + 14 50^ 



Water 



98H2O + Energy 



Proteins 



The amino acids that result from diges- 

 tion of proteins are much more important 

 than carbohydrates or fats in the synthesis of 



protoplasm. Amino acids are the "building 

 blocks" of proteins. In order to grow, the 

 human body must have amino acids. It 

 needs them to build muscles, skin, hair, nails, 

 the various organs, etc. The growing cell is 

 provided with a mechanism which enables it 

 to put together the various amino acids in 

 the number and proportion required to 

 make a specific protein. Amino acids may 

 be oxidized in production of energy but this 

 is a minor function. Very little protein is 

 stored in the body; but when carbohydrates 

 and fats are used up, the proteins supply 

 energy, that is, the protoplasm itself is oxi- 

 dized. The proteins in the animal body can 

 be built up from amino acids, but the body 

 can also convert them into simple sugars, 

 and simple sugars into fat. 



SELECTED COLLATERAL 

 READINGS 



Baitsell, G.A. Human Biology. McGraw-Hill, 

 New York, 1950. 



Carlson, A. J., and Johnson, V. The Machinery 

 of the Body. Univ. Chicago Press, Chicago, 

 1953. 



Gaffon, H. (ed.). Research in Photosynthesis. 

 Interscience Publishers, New York, 1957. 



Gerard, R.W. (ed.). Food for Life. Univ. of 

 Chicago Press, Chicago, 1952. 



Kimber, D.C., Gray, C.E., Stackpole, C.E., and 

 Leavell, L.C. Textbook of Anatomy and 

 Physiology. Macmillan, New York, 1956. 



Mitchell, P.H. Textbook of General Physiol- 

 ogy. McGraw-Hill, New York, 1956. 



Scheer, B.T. Comparative Physiology. Wiley, 

 New York, 1948. 



