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Explain the role of membranes as permeability barriers in passive transport.
Explain the role of membranes as permeability barriers in passive transport.
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.
What is the permeability coefficient for water in lipid bilayers and how does it relate to osmosis?
What is the permeability coefficient for water in lipid bilayers and how does it relate to osmosis?
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 which cells may the movement of water be facilitated by specific water channels, and what are these channels called?
In which cells may the movement of water be facilitated by specific water channels, and what are these channels called?
In some cells, such as the kidney proximal tubule, the movement of water may be facilitated by specific water channels called aquaporins.
Why is the transverse movement of hydrophilic molecules across an intact biological membrane a rare event?
Why is the transverse movement of hydrophilic molecules across an intact biological membrane a rare event?
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How is the movement of ions and hydrophilic molecules across a membrane mediated and regulated?
How is the movement of ions and hydrophilic molecules across a membrane mediated and regulated?
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