164 MOVEMENT OF CILIA AND FLAGELLA 



5. The Energy Relationships of Cilia and Flagella 



Evidence has been presented that the energy for the beating 

 of ciha is derived from glycolysis and the citric acid cycle, and is 

 carried to the site of utilization by the high energy phosphate 

 bonds of ATP. The nine peripheral fibrils of cilia have been 

 found to carry ATP-ase activity. Estimates of the energy 

 available for use in the movement of cilia or flagella can be based 

 on observed chemical changes, and also estimates of the energy 

 required in this movement can be based on theoretical calculations 

 and in some cases on actual measurements. 



The energy for movement of bull sperm under anaerobic 

 conditions may be obtained by the breakdown of exogenous 

 fructose to lactic acid. Rothschild (1961) w^as able to measure the 

 rate of fructolysis by bull sperm, and, know^ing the free energy 

 change associated with the reaction, he found that at 37°C the sperm 

 were able to release energy at a rate of 6 • 10 x 10~^ erg/sperm/sec. 



The rate of energy expenditure in overcoming the resistance of 

 external viscosity in the movement of sperm can be calculated 

 from a theoretical equation quoted by Rothschild (1961); in this 

 calculation the energy used along the whole tail is integrated. 

 By substitution of measured values from bull sperm in this 

 equation, it was found that each bull sperm uses 2*11x10"'^ 

 erg/sec (at 37 °C) in movement. This is near one-thirtieth of the 

 energy available from fructolysis. On the assumption that the 

 energy for movement is carried by ATP and released by ATP 

 hydrolysis, Rothschild found that the energy available for move- 

 ment could not exceed 1 ^S x 10~® erg/sperm/sec, which still leaves 

 a factor of about 10 between the energy available and that required. 

 Similar calculations on the sea urchin sperm gave a figure of 

 2*10 x 10~' erg/sperm/sec for the energy dissipation in movement 

 at 17°C. In both sea urchin and bull sperm only the work done 

 against external resistance has been considered in the theoretical 

 calculations, the energy required to bend or compress elements 

 of the tail is not known at all. 



Other data on the bull sperm are available from the work of 

 Nelson (1958), who found by the use of a formula of Carlson 

 that each sperm dissipates energy at a rate of 3 -15 x 10~^ erg/sec. 

 He also found from biochemical studies that enough succinic 



