What is the approximate time required for a hemoglobin molecule to diffuse through a cell membrane? The diffusion constant D is approximately proportional to 1/r, where r is the diameter of the diffusing particle or atom. Estimate the diffusion constant of a hemoglobin molecule from the value of D for an oxygen molecule in Table 15.1.

 

TABLE 5.1 Solar System Data: Properties of Several Objects in the Solar System, Including the Planets and Two of the Largest Dwarf Planets (Pluto and Eris) Mean Orbital Orbital Radius Orbital Period Mass Radius of Object (x 10 m) (x 10" m) (x 1024 kg) Eccentricity Name (years) 2.44 0.330 Mercury 0.579 0.240 0.21 Venus 1.08 0.615 6.05 4.87 0.007 Earth 5.98 1.50 1.00 6.37 0.017 2.28 Mars 1.88 3.39 0.644 0.093 Jupiter 7.78 11.9 71.5 1900 0.048 Saturn 14.3 29.4 60.3 0.054 568 Uranus 28.7 83.8 25.6 86.6 0.047 24.8 102 Neptune 45.0 164 0.009 0.25 Pluto 59.1 248 1.14 0.0131 100 560 Eris 2.4 0.44 Earth's Moon 27.3 days 3.85 x 10% m 1.74 0.0735 0.055 Sun 6.96 x 108 m 1.99 1030 kg