BACTERIAL CELL WALL 



101 



the cell, as outside (Gale, Taylor). (An alternative explanation here is that inside the 

 cell the constituents may be adsorbed on surfaces and not freely diffusible under 

 normal circumstances ; on the other hand such diffusion against a concentration 

 gradient occurs only when the cell is actively metabolising and providing free energy.) 



TT 



Culture / 

 / 



Membrane 

 C ytopl asm 



^* Cytoplasmic 



/X/ 



Fio. 18 

 Diagrammatic visualisation of Section of part of Bacterial surface 



The cell wall, on the other hand, may be some kind of hpoprotein which adsorbs an 

 entering molecule, produces necessary chemical changes in it (e.g., converts glutamic 

 acid to glutamine) and then injects it into the cell interior after the inner side of the 

 cell wall has reconverted it back into the original form (Glutamic acid). If this is so 

 our diagram should be compHcated by indicating the cell wall as bristHng with enzyme 

 systems. 



Having negotiated the cell wall, by an agreed mechanism, our glucose molecule 

 is now broken down. The enzymes in the diagram are represented as tethered to the 

 comparatively fragile cytoplasmic membrane. (Stacey visualises some such arrange- 

 ment for the magnesium-ribonucleate-protein Gram complex.) The advantage from 

 our chemical engineer's point of view is that the bringing together of the substrate, 

 enzyme, coenzyme and free energy is much simpler if the chemical plant and energy 

 supplies are fixed in appropriate positions for the flow of raw materials, and are not all 



