4.3 Limitations of passive transport Most eukaryotic cells are about 10 m in dia

Question

4.3 Limitations of passive transport Most eukaryotic cells are about 10 m in diameter, but a few cells in your body are about meter long. These are the neurons running from you spinal cord to your feet. They have a normal-sized cell body, with various bits sticking out, notably the "axon." Neurotransmitters are small molecules synthesized in the cell body, but needed at the tip of the axon. One way to get them to their destination is just to let them diffuse there. Model the axon as a tube 1 m long and 1 um in diameter. At one end of the axon, the concentration of a small molecule is maintained at one millimolar (that is, (10-3mole)/(10-3m3)). Some process removes all the molecules arriving at the other end. a. Estimate how many molecules per second arrive at the end.

Explanation / Answer

ans) given boundary conditions C (0) = 1 mmole/ L and C (L) = 0. Then I assumed the flux was constant and found a linear function and expressed the flux based on the slope of that graph j = DC_0/L. Then multiplied by area.

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