68 CARBOHYDRATES 



Immuno'polysaccharides 



Certain polysaccharides, unknown until fairly recently, doubtless play 

 a role of greater importance in our lives than many of the related com- 

 pounds with which we are more familiar. These are the immuno-poly- 

 saccharides, which pneumococci, streptococci, tubercle bacilli, and many 

 other types of bacteria synthesize and transfer to the solution, blood as 

 well as culture media, in which they grow. Each type produces a char- 

 acteristic chemical compound or "specific soluble substance," the presence 

 of which in the blood stream of an individual stimulates production 

 of antibodies, and thus builds up immunity to a given disease. Since 

 these polysaccharides are "type specific," it is apparent that each must 

 differ chemically from the other. D-Glucose, D-glucosamine, and various 

 sugar acids have been identified among the hydrolysis products of these 

 immuno-polysaccharides. A recent contribution to immuno-chemistry 

 is the discovery that appropriate synthetic organic compounds-containing 

 glucuronic and galacturonic acids, as w^ell as the specific polysaccharides 

 of bacterial origin, may evoke production of antibodies and thus establish 

 immunity to a particular disease in an experimental animal. These results 

 show the great importance of the sugar acids and throw new light on 

 the structure of the specific polysaccharides. 



REVIEW QUESTIONS ON CARBOHYDRATES 



1. Define: carbohydrate, simple sugar, uronic acid, heteropolysaccharide, asym- 

 metric carbon atom, optical rotation, desoxysugar, glycoside. 



2. How many substances of each of the following types can theoretically exist: 

 aldopentose, 2-ketohexose, aldohexose? Explain. 



3. Name four disaccharides made up of glucose units only and explain how they 

 differ from each other. 



4. Give two commercial sources of (1) sucrose, (2) cellulose, (3) starch; one 

 commercial source of (4) glucose, (5) lactose. Briefly outline the procedure in the 

 manufacture of sucrose from one of the above sources. Outline the steps in the 

 manufacture of glucose. 



5. Explain the terms: (1) invert sugar, (2) hydrolysis, (3) sucrase, (4) pentosan, 

 (5) mercerization, (6) celluloid. 



6. Write equations and name the products in: (1) the photosynthesis of glucose, 

 (2) the hydrolysis of sucrose, (3) the digestion of starch by saliva. 



7. What are the chief carbohydrates in (1) honey, (2) fruits, (3) liver, (4) blood, 

 (5) milk, (6) conden.sed milk, (7) cereals? Approximately what is the percentage 

 of the carbohydrate named in each case? 



8. Explain the terms: (1) pentose, (2) photosynthesis, (3) pectin, (4) dextrin, 

 (5) beta lactose, (6) cellophane, (7) rayon. 



9. Write equations and name the products in: (1) the hydrolysis of starch by 

 acid, (2) the mucic acid test for galactose, (3) a positive Fehling's test. 



10. By means of graphic formulas explain how glucose, galactose, and fructose may 

 all have the same molecular formula, CoHiiOe, and still be different chemical com- 

 pounds. Explain why sucrose does not reduce Fehling's solution, while maltose does. 



