68 



METABOLIC PATHWAYS IN MICROORGANISMS 



Claude (3, 4) and others, of the close association between 

 the group of enzymes necessary for the process, and their 

 presence in mitochondria. 



Consider for a moment the inclusions, or subcellular 

 particles, that may be observed in a typical cell. A glance 

 at the diagram of a generalized cell in Fig. 3.2 will reveal 

 the nucleus, the large moon-shaped object in the upper 

 center; the mitochondria, or "large granules," as these are 

 called, which are smaller, yet easily visible under an ordi- 

 nary high-power microscope; and the microsomes, or endo- 

 plasmic reticula, which resemble small strings of spaghetti, 

 and which can be viewed in some detail in an electron micro- 

 graph. Other inclusions may be seen at times, such as food 

 particles; but the foregoing are the principal ones. Pal- 

 ade's work, one of the plates of which is reproduced in 

 Fig. 3.3 (5), has contributed much to our knowledge in 

 this area. 



Examples of the association between Krebs cycle enzymes 

 and mitochondrial activity were to be found easily. With 



TABLE 3.1 



Size, Sedimentation Time, Gross Composition, and 

 Succinoxidase in Liver Cellular Fractions 



After Lehninger (6). 



