A (biológiai) élet folyamatszabályozása
Regulatory Enzymes Act as Metabolic Valves Figure 14-16 Although not at equilibrium with their surroundings, adult organisms generally exist in a steady state. A constant influx of fuel and nutrients and a constant release of energy and waste products allow the organism to maintain a constant composition. When the steady state is disturbed by some change in external circumstances or fuel supply, the temporarily altered fluxes through individual metabolic pathways trigger regulatory mechanisms intrinsic to each pathway. The net ef fect of all of these adjustments is to return the organism to the steady state – to achieve homeostasis . Because of the central role of ATP in cellular activities, evolution has produced catabolic enzymes with regulatory properties that ensure a high steady-state concentration of ATP, "high" in this context meaning high relative to the breakdown products ADP and AMP. The flux through a biochemical pathway depends on the activities of the enzy...