3 



Structure and Function of 

 Cytoplasmic Organelles 



As NOTED EARLIER, the cytoplasHi of most cells contains a number of 

 organelles. Until recently, knowledge of the origin, structure, and function 

 of most of these has been something less than satisfactory. During the 

 last decade the development of a number of techniques has made it 

 possible to improve our knowledge by a considerable factor. Among the 

 more important technical advances have been the following: (1) Im- 

 provement in methods of preparing cells and tissues for observation with 

 the electron microscope has made it possible to describe the fine structure 

 of the cytoplasm and the contained organelles at levels which are 

 measured in angstroms rather than microns; (2) improvement in tech- 

 niques of isolation and preparation of various cell components has 

 allowed the biochemist to study many of the in vitro biochemical po- 

 tentials of specific organelles and even fractions of them; and (3) 

 development of techniques of autoradiography, the general use of tracer 

 elements, and specific cytochemical tests have provided much useful 

 information concerning the location of chemical compounds and their 

 function and interrelationship in the cell. 



When information from these and other techniques is assessed, it 

 becomes possible to provide what appears to be a fairly reliable picture 

 of the major subcellular particles (Figure 3-1). In the discussion to 

 follow, the more generally accepted concepts of structure and function 

 of the better-known cell components will be outlined. 



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