The Chemical and Physical Structure of Protoplasm - 77 



Table 4-5— A Series of Relatively Simple Organic Compounds 



Glucose. Glucose is a most important 

 carbohydrate. In every cell glucose can pro- 

 vide not only energy, but also matter, for the 

 synthesis of quite a few other essential com- 

 pounds. 



Pure glucose, like table sugar, is a white 

 crystalline sweet-tasting solid, which is very 

 soluble in water. But compared to sucrose, 

 glucose is more active chemically; and glu- 

 cose, due to the smaller size of its molecules, 



can pass through cell membranes more easily 

 than sucrose. 



Glucose as a Protoplasmic Fuel. The 

 energy expended by a cell when it moves and 

 performs its other activities all comes from 

 the decomposition of organic compounds in 

 the protoplasm. These organic compounds 

 possess a rich fund of intramolecular energy; 

 and in serving as fuel, large energy-rich mole- 

 cules continually decompose into simpler end 



