10 Membrane permeability Questions What molecules are able to diffuse across membrane bilayers freely? How do ions and small polar molecules permeate hydrophobic membrane bilayers? What is the difference between passive and active transport across membranes? What is the difference between primary and secondary active transport? Diffusion across lipid bilayers Lipid bilayers are freely permeable to small unchanged molecules (e.g. O2, CO2, urea) and hydrophobic molecules (e.g. steroids) but are impermeable to ions and large polar molecules (e.g. glucose, Na+). Passive transport is linearly related to concentration. Surprisingly, membranes are relatively permeable to water, which diffuses passively up the concentration gradient of a solute, the osmotic gradient. In some cells (e.g. kidney proximal tubule), the movement of water may be facilitated by specific water channels, called aquaporins. Membranes as permeability barriers Only gold members can continue reading. Log In or Register to continue Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Like this:Like Loading... Related Related posts: DNA and gene transcription Ion transporters in cellular physiology Electrical conduction in nerves Proteins and protein function Stay updated, free articles. Join our Telegram channel Join Tags: The Flesh and Bones of Medical Cell Biology Jun 18, 2016 | Posted by admin in BIOCHEMISTRY | Comments Off on Membrane permeability Full access? Get Clinical Tree
10 Membrane permeability Questions What molecules are able to diffuse across membrane bilayers freely? How do ions and small polar molecules permeate hydrophobic membrane bilayers? What is the difference between passive and active transport across membranes? What is the difference between primary and secondary active transport? Diffusion across lipid bilayers Lipid bilayers are freely permeable to small unchanged molecules (e.g. O2, CO2, urea) and hydrophobic molecules (e.g. steroids) but are impermeable to ions and large polar molecules (e.g. glucose, Na+). Passive transport is linearly related to concentration. Surprisingly, membranes are relatively permeable to water, which diffuses passively up the concentration gradient of a solute, the osmotic gradient. In some cells (e.g. kidney proximal tubule), the movement of water may be facilitated by specific water channels, called aquaporins. Membranes as permeability barriers Only gold members can continue reading. Log In or Register to continue Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Like this:Like Loading... Related Related posts: DNA and gene transcription Ion transporters in cellular physiology Electrical conduction in nerves Proteins and protein function Stay updated, free articles. Join our Telegram channel Join Tags: The Flesh and Bones of Medical Cell Biology Jun 18, 2016 | Posted by admin in BIOCHEMISTRY | Comments Off on Membrane permeability Full access? Get Clinical Tree
