Common Pafhways of Cellular Meiabolism - 157 



10. 



13. 



14. 



15. 



reduction reaction occur spontaneously? 

 Give an example to illustrate the action of 

 any dehydrogenase. Why are dehydrogenation 

 reactions important in the cell? 

 Explain the term "primary acceptors." Spe- 

 cify four compounds in this category. Dis- 

 tinguish among these: (a) as to molecular 

 structure; (b) as to vitamin constituents; and 

 (c) as to recipients of their electron-hydrogen 

 transmission. 



Differentiate between oxidases and dehydro- 

 genases. 



Specify four components usually represented 

 in the cytochrome system. Explain how the 

 cytochrome system operates and why it is 

 important in the cell. 



Define the term "decarboxylation." Give a 

 reaction that exemplifies this process. To 

 what extent is decarboxylation involved in 

 the catabolism of glucose? 

 Work out the reaction involved when lactic 

 acid (CH 8 CHOHCOOH) undergoes de- 

 carboxylation. Can you specify the organic 

 compound produced by this reaction? 

 What is the opposite of decarboxylation? 

 Explain the importance of carbon dioxide 

 fixation. 



16. 



17. 



19. 



20. 



21. 

 22. 



23. 



Explain the term "glucose activation." What 

 sort of reaction is involved in such activa- 

 tion? Does the cell gain or lose energy in 

 such a transaction? 



Differentiate among transphosphorylation, 

 dephosphorylation and phosphorolysis. Give 

 an example of each. 



What is known about the chemical structure 

 of coenzyme A? Evaluate the importance of 

 coenzyme A in cellular metabolism generally. 

 Why is the Krebs cycle also designated: (a) 

 as the citric acid cycle and (b) as the "energy 

 wheel of cellular metabolism"? 

 What main types of metabolites are even- 

 tually catabolized in the Krebs cycle? What 

 is the net result of this catabolism? 

 What are mitochondria and why are these 

 cytoplasmic structures so important? 

 Sketch in the metabolic pathways by which 

 many cells can convert: 



a. proteins (amino acids) into carbohy- 

 drates 



b. carbohydrates (glucose) into fats 



c. proteins into fats 



d. glucose into certain amino acids 

 Evaluate the contributions of Fritz Lip- 

 mann and Hans Krebs. 



FURTHER READINGS 



Dynamic Aspects of Biochemistry, 3d ed., by 

 E. Baldwin; New York, 1957. 

 "The Metabolism of Fats," by D. E. Green, 

 and "The Structure of Proteins," by Pauling, 

 Corey, and Hayward, in The Physics and 

 Chemistry of Life, a collection of articles from 

 Scientific American; New York, 1955. 



3. Cellular Physiology and Biochemistry, by 

 W. D. McElroy; Englewood Cliffs, N. J., 1961. 



4. "How Cells Transform Energy," by A. L. 

 Lehninger, in "The Living Cell." special issue 

 of Scientific American, September 1961. 



