102 LIPIDES (fats and RELATED SUBSTANCES) 



to occur in cerebrosides and sphingomyelin are saturated, or have only- 

 one double bond, and contain a large number of carbon atoms (mostly C24 

 or C26)- 



REVIEW QUESTIONS ON LIPIDES 



1. Explain the terms: (1) fat, (2) phospholipide, (3) wax, (4) sterol, (5) soap, 

 (6) saponification, (7) hydrogenation of oils, (8) detergent, (9) antioxidant. 



2. Explain chemically why tallow is a solid and olive oil is a liquid. Name the 

 chief fatty acids obtained from each. 



3. Give (1) the elements in (a) carotene, (b) cholesterol, (2) the equation for the 

 saponification of triolein with potassium hydroxide, (3) the chemical groups con- 

 tained in lecithin, (4) the graphic formula of glycerol, (5) the formula for one con- 

 stituent in a wax. 



4. Discuss the factors that operate to make a fat rancid. 



5. Explain the differences in the chemical composition of the ether extracts (fat) 

 of various food materials. Compare, for example, the ether extracts of oatmeal and 

 spinach. 



6. Explain the terms (1) simple glyceride, (2) mixed glyceride, aad discuss their 

 occurrence in a natural fat. 



7. Explain how an oil is made commercially. What is the source of (1) linseed 

 oil, (2) tallow, (3) "Crisco"? 



8. Explain the significance and the limitations of the term "fat" as used in tables 

 of food analyses. 



9. Why is January milk so pale in color as compared with June milk? Can you 

 think of any way by which winter milk could be improved in color? 



10. Generally compare the biological roles of true fats, waxes, and complex lipides. 



11. Correct the following statements if incorrect: (1) "Dreft" is the trade name of 

 a cleaning agent that does not form an insoluble precipitate with hard water. Chem- 

 ically, it is the sodium salt of sulfated aliphatic alcohols, chiefly lauryl. (2) Hydro- 

 genation of coconut oil will produce a solid fat. (3) Glycerine and glycerol are dif- 

 ferent names for the same compound. (4) Stearin and sterol also mean the same 

 thing. (5) Linseed oil is obtained from the linen seed. 



REFERENCES AND SUGGESTED READINGS 



Bloor, W. R., Biochemistry of the Fatty Acids, Reinhold Publishing Corporation, 



New York, 1943. 

 Bull, H. B., Biochemistry of the Lipides, John Wiley and Sons, Inc., New York, 



1947. 

 Chargaff, E., Ziff, M., and Rittenberg, D., "A Study of the Nitrogenous Constituents 



of Tissue Phosphatides," J. Biol. Chem., 144, 343 (1942). 

 Hilditch, T. P., Chemical Constitution of Natural Fats, John Wiley and Sons, Inc., 



New York, 1940. 

 Jamieson, G. S., Vegetable Fats and Oils, Reinhold Publishing Corporation, New 



York, 1932. 

 Markley, K. S., Fatty Acids, Interscience Publishers, Inc., New York, 1947. 

 Thannhauser, S. J., and Schmidt, G., "Lipins and Lipidoses," Physiol. Rev., 26, 275 



(1946). 

 Wittcoff, H., The Phosphatides, Reinhold Publishing Corp., New York, 1951, 



