36 PHOTOSYNTHESIS 



group and its mode of attachment is the same in C}1;o- 

 chromes c and / and the observed differences presumably 

 arise from differences in the protein component. 



Cytochrome 63 is not confined to green organs; cyto- 

 chrome / appears to be confined to the chloroplasts. Cyto- 

 chrome / predominates in the leaf, its concentration being 

 about 10 times greater than that of the other cytochromes. 

 The cytochromes show high specificity in oxidation-reduc- 

 tion reactions. In a later chapter we shall see that photo- 

 synthesis is essentially an oxidation-reduction reaction and 

 it is possible that cytochrome/ may play the part of a carrier 

 in the process. It may be significant that the ratio of the rate 



TABLE 3.4 



HAEMATIN COMPOUNDS IN THE PLANT 



