Becker's World of the Cell 9th Edition by Lewis Kleinsmith, Jeff Hardin, Gregory Paul Bertoni

Exercise 7

Following Ras activation. It is possible to use engineered molecules to follow the activation of individual Ras molecules in stimulated cells using a technique called fluorescence resonance energy transfer (FRET; see the Appendix for further details). Figure shows the time course of Ras activation following stimulation by epidermal growth factor (EGF).
(a)Based on the graph, how long does it take for maximal Ras activation to be achieved
(b)Why does Ras activity decline after a few minutes, even when EGF is still present
Figure Activation of Ras following Epidermal Growth Factor (EGF)stimulation.