RESUMO
A computer model is described which is capable of predicting changes in cell composition, cell size, cell shape, and the timing of chromosome synthesis in response to changes in external glucose limitation. The model is constructed primarily from information on unrestricted growth in glucose minimal medium. The ability of the model to make reasonable quantitative predictions under glucose-limitation is a test of the plausibility of the basic biochemical mechanisms included in the model. Such a model should be of use in differentiating among competing hypotheses for biological mechanisms and in suggesting as yet unobserved phenomena. The last two points are illustrated with the testing of a mechanism for the control of the initiation of DNA synthesis and predictions on cell-width variations during the division cycle.
Assuntos
Simulação por Computador/história , Escherichia coli/crescimento & desenvolvimento , Glucose/história , Replicação do DNA , Escherichia coli/genética , Escherichia coli/metabolismo , Glucose/metabolismo , História do Século XX , Biossíntese de Proteínas , Transcrição GênicaRESUMO
A computer model is described which is capable of predicting changes in cell composition, cell size, cell shape, and the timing of chromosome synthesis in response to changes in external glucose limitation. The model is constructed primarily from information on unrestricted growth in glucose minimal medium. The ability of the model to make reasonable quantitative predictions under glucose-limitation is a test of the plausibility of the basic biochemical mechanisms included in the model. Such a model should be of use in differentiating among competing hypotheses for biological mechanisms and in suggesting as yet unobserved phenomena. The last two points are illustrated with the testing of a mechanism for the control of the initiation of DNA synthesis and predictions on cellwidth variations during the division cycle.
RESUMO
An instrument designed to measure quantitatively the contour of the human cornea is described. This apparatus can be used to btain enlarged cross sections of the cornea without harming the eye in any way. An image of a brightly illuminated slit is projected onto the cornea. The intersection of the slit image with the surface of cornea constitutes a section plane through the cornea. The undistorted, enlarged images of selected sections are recorded photographically as corneagrams.