. Animal growth and development. Embryology; Growth; Biology; Growth; Embryology; Animals -- growth & development. 90 Cell Interactions during Growth and Morphogenesis Three kinds of mutants have been isolated: Mutant 1 could grow if supplied with ornithine, citrulline, or ar- ginine (, the enzyme that catalyzes reaction 1 is miss- ing)- Mutant 2 could grow if supplied with citrulline or arginine, but not if supplied with ornithine. However, ornithine accumu- lated in the cells and seeped out into the medium (, the enzyme-catalyzing reaction 2 was missing). Mutant 3 could grow only
. Animal growth and development. Embryology; Growth; Biology; Growth; Embryology; Animals -- growth & development. 90 Cell Interactions during Growth and Morphogenesis Three kinds of mutants have been isolated: Mutant 1 could grow if supplied with ornithine, citrulline, or ar- ginine (, the enzyme that catalyzes reaction 1 is miss- ing)- Mutant 2 could grow if supplied with citrulline or arginine, but not if supplied with ornithine. However, ornithine accumu- lated in the cells and seeped out into the medium (, the enzyme-catalyzing reaction 2 was missing). Mutant 3 could grow only if supplied with arginine, not with orni- thine or citrulline. However, citrulline accumulated in the cells and seeped out into the medium (, the enzyme- catalyzing reaction 3 was missing). If, as shown in Fig. 43, the three mutant types are streaked on agar containing a tiny amount of arginine, synergistic growth occurs. Mutant 3 grows very sparingly until the arginine in the medium is used up, and then it stops. It continues, however, to generate energy by oxidation and to carry out a wide variety of biochemical reactions, including the synthesis of citrulline, which accumulates and seeps out into the medium. Mutant 2, growing nearby, can convert the citrulline to arginine. Since mutant 3 makes a large quantity of citrulline, mutant 2 can grow very well. If the mutant 2 cells do not lie next to mutant 3, they grow very sparingly, but they stiU can metabolize and accumulate ornithine. Since mutant 1 can. Fig. 43. Synergistic growth by three mutant types of E. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Sussman, Maurice. Englewood Cliffs, N. J. , Prentice-Hall
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