150 



Muscles /8 : 4 



phosphate. Furthermore, if frogs' muscles are soaked in 50 per cent 

 glycerol for months to remove the smaller molecules and then ATP is 

 added, the muscles contract. These brief summaries of many detailed 

 experiments can be interpreted to indicate the role of ATP in muscular 

 contraction, or they may all be artifacts or physiologically unimportant 



DPNH to 



Cytochrome 



System 



6H 2 



H to DPN in 

 Cytochrome System 



About 

 34ATP 



I2H 2 



Figure 7. Major steps in the oxidation of glucose. The input 

 consists of glucose and oxygen. Water and GO a are formed 

 and energy is stored as ATP, the form used in muscular con- 

 traction. Krebs cycle and cytochrome system enzymes are in 

 the mitochondria; glycolytic enzymes are not in the mito- 

 chondria. 



facts. Direct, spectrophotometric measurements support the latter 

 view, that ATP does not react with the contractile elements. All that 

 is certain is that protein changes occur when the muscle contracts and 

 that ATP is used up to supply the energy for this process. 



The steps in the synthesis of ATP from ADP and (P) at the expense of 



