1. In order to function, cells need to take up nutrients such as glucose from th
ID: 31448 • Letter: 1
Question
1. In order to function, cells need to take up nutrients such as glucose from their environ- ment. These nutrients must be transported across the plasma membrane so that they can be processed by the metabolic pathways that utilize them, e.g. as glucose is utilized by the glycolytic pathway a) Set up and solve the equation of molar conservation of glucose, defining the system as a single cell. As outlined in class, the rate of accumulation of a conserved quantity Cin this case moles of glucose is equal to the net rate of transport into the system plus the net consumption rate. You may assume that the net transport across the plasma membrane is proportional to the molar concentration difference across the membrane A Acell Fmem P (Cout Cin) (1) cell and that the net molar consumption rate of glucose inside the cell is given by (2) REC where Cout and Cin are the molar concentrations of glucose outside and inside of the cell, respectively, P is the membrane permeability, and k is the rate constant for consumption by the glycolysis pathway (both P and k are constants and have units s-1). Assume that Cout is a constant, and derive the expression for Cin as a function of time given an initial concentration inside the cell of Cin,0. Which parameter(s) determine(s) the approach to steady-state? Which parameter(s) determine(s) the steady-state concentration of glucose? (b) Using excel, matlab, or similar software, plot Cin(t) using the following values 15 mM, out 10 mM. Repeat the plots with 1 s 1 s in,0 k 0.1 s 1 and 10 s 1. Under which of the three conditions for k is glucose utilization maximal Under these conditions, is the intracellular concentration of glucose highest or lowest of the three cases?Explanation / Answer
a)
The parameters that determine the steady-state concentration of glucose are:
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