The small molecule cyclic AMP (cAMP) takes about 0.2 second to diffuse 10 µm, on average, in a cell. Suppose that cAMP is produced near the plasma membrane on one end of the cell; how long will it take for this cAMP to diffuse through the cytosol and reach the opposite end of a very large cell, on average? Assume that the cell is 200 µm in diameter.
(a) 4 seconds
(b) 16 seconds
(c) 80 seconds
(d) 200 seconds
Answer: C