Do hydrophobic amino acids pass through the lipid bilayer?
Can a hydrophobic amino acid like leucine pass through the lipid bilayer (without passing through a channel nor a protein)?? I know that nonpolar and relatively small molecules can pass through the membrane. However, amino acids in general have their COOH and NH3 group charged as COO- and NH4+ at physiological pH... So can it pass through the lipid bilayer just because its R group is nonpolar?
Comments
No!
exactly because of the reason you stated in your last sentence.
At biological pH (7.2 - 7.4) the NH4+ and the COO- groups are ionzied hence the species are charged. Such charged species are called "ions" and they are not able to cross the membrane at all. In fact the permeability of the membrane is much less for charged species then for actual hydrophilic compounds, that is why amino acids and the like are taken up by the cell via. active transport, usually as co-transport with sodium.
Osmosis- what happens while 2 fluid ideas of same sort yet diverse concentrations are separated by using a semipermeable membrane. The ideas will then attempt to get into stability by using getting their concentrations equivalent. So the greater targeted answer would be thinned by using circulate of cloth (normally sovent) during the membrane, and the different answer is effectively thickened. this aspects the mechanism for ionic balances in cells. Diffusion-extremely comparable to osmosis, yet no membrane in contact. Jut diverse concentrations in diverse adjacent areas. same balancing-out gadget.