Inside the Cell 



47 



thirty-eight molecules of atp are formed for the oxidation of one 

 molecule of glucose. 



It is of interest to compare the efl&ciency of the oxidation of fuel 

 in a power station with that in the cell. The overall efficiency of 

 even large mechanical power stations rarely exceeds 15 per cent. 

 Measurements have been made of the yield of atp from glucose in 

 chopped up pigeon-breast muscle. It was found that at least 70 per 



glycolytic 

 cycle 



(non-oxidative) 



oxidative cycle 



carbon dioxide 

 and 

 water 



carbo- 

 hydrates . 

 ' /\oxygen 



i I 



♦►pyruvic acid 



proteins 



nucleic 



acids 



r^ 



synthetic 

 products 



_y 



represents ATP 



FIG. 11. How the cell obtains its energy. A flow sheet of the fuel station 

 within the cell. (Modified from a diagram by Professor H. Lettre) 



cent of the free energy of the glucose was obtained as high-energy 

 ATP : the fuel station in the cell is evidently highly efficient. 



But the cell is self-contained. It not only provides its own power 

 supply, but it also uses within itself the energy provided. Some of this 

 energy may be used to perform muscular work, but it is mainly used 



