Membrane Permeability and Cell Volume Lecture Quiz

Membranes act as permeability barriers to all charged and hydrophilic molecules, making the transverse movement of hydrophilic molecules across an intact biological membrane a rare event.

The permeability coefficient for water in lipid bilayers is 5 x 10^-3 cm s^-1, and water will diffuse passively across lipid bilayers up the concentration gradient of a solute, the osmotic gradient.

In some cells, such as the kidney proximal tubule, the movement of water may be facilitated by specific water channels called aquaporins.

<p>The large free energy change required for a small hydrophilic molecule or ion to traverse the hydrophobic core of the lipid bilayer makes the transverse movement of hydrophilic molecules across an intact biological membrane a rare event.</p> Signup and view all the answers

<p>The movement of ions and hydrophilic molecules across a membrane is mediated and regulated by specific membrane transport systems.</p> Signup and view all the answers