Question

Compared to glycerol (shown), O₂ has a higher rate of passive permeability through a cell membrane. Which of these correctly explains why? Choose all that apply.

a. The most energetically challenging part of traversing a membrane is passing through the hydrophobic interior. Hydrophobic molecules can more easily do this and so can pass through membranes more easily.

b. The most energetically challenging part of traversing a membrane is passing through the polar head groups. Polar molecules can more easily do this and so can pass through membranes more easily.

c. Being composed of two identical atoms, electrons are shared equally within O₂, making it non-polar, while glycerol is polar.

d. Glycerol is more hydrophobic than O₂, which contains highly electronegative atoms.

e. O₂ is smaller than glycerol

Answer 1

a. The most energetically challenging part of traversing a membrane is passing through the hydrophobic interior. Hydrophobic molecules can more easily do this and so can pass through membranes more easily.

c. Being composed of two identical atoms, electrons are shared equally within O₂, making it non-polar, while glycerol is polar.

e. Oxygen is smaller than glycerol.

The lipid bilayer membrane is composed of outer and inner hydrophilic region and middle hydrophobic region.The permeability of a molecule depends on its ability to dissolve with in a non polar solution. The more nonpolar a molecule is, the more likely it is to dissolve with in the hydrophobic internal environment of the bilayer membrane. This implies that small, non polar ,hydrophobic gases like oxygen can cross membranes rapidly. while glycerol being small polar molecule (since the -O-H bond in glycerin is polar ) but have hydrophobic tail, can also pass through the membrane but at very slow rate.