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Hydrophilic molecules are more stable in water as compared to lipid so they prefer to stay in water and not go inside lipid. Hydrophobic molecules are more stable in lipid as compared to water so they prefer to leave water and move freely into lipid. You are saying that hydrophilic part of membrane will obstruct the movement of hydrophobic ...
Now, what happens is that when a molecule has to enter the cell it first has to interact with the polar part of the lipid membrane and then with the inner non-polar part of the membrane to pass through, hence if it is a polar molecule it will face repulsions and will not be able to pass through without the assistance of transmembrane proteins ...
I have difficulty in understanding the reason why certain molecules can pass through phospholipid bilayers. Firstly, I understand that the outer layer of the lipid bilayer is hydrophilic - my understanding is that they "like water" and can interact better with water. Bilayers can absorb hydrophobic substance like N₂ and O₂.
Importantly, only small, relatively hydrophobic molecules are able to diffuse across a phospholipid bilayer at significant rates (Figure 12.15). Thus, gases (such as O 2 and CO 2), hydrophobic molecules (such as benzene), and small polar but uncharged molecules (such as H 2 O and ethanol) are able to diffuse across the plasma membrane. Other ...
It is commonly told that, hydrophobic/ lipophilic/ nonpolar molecules can quite easily pass phospholipid bilayer, and hydrophilic (polar or ionic) molecules can't pass (when no protein aid that); because hydrophobic nature of the lipid. But in the same logic, hydrophobic molecules shouldn't pass through the bilayer.
Hydrophillic and hydrophobic molecules do not repel but, rather, attract one another through van der Waals interactions. The tendency of hydrophobic molecules to aggregate in aqueous solution (ie the hydrophobic effect) is, instead of some repulsive force, actually driven entropically.
With those two preferences in play, the lipid bilayer forms. On a smaller scale, micelles also form spontaneously, but this doesn't offer the compartmentalization required for biological functions. It would appear that the conditions for an ordered bilayer are so favorable that they take precedence over any other orientation or combination.
Yes, Since the lipid bilayer of cells is nonpolar, only non-polar substances can pass directly through the bilayer without the need for any help by membrane transport proteins. This answer is ...
0. Polar and nonpolar molecules don't actually "repel", it's that polar molecules attract each other much more than nonpolar molecules attract anything. Therefore, to take a polar molecule from the (polar) water on one side of the membrane and bury it in the nonpolar region in the middle of the membrane is difficult because it means breaking ...
During dissolution water interacts with the solute molecule; if the strength of interaction between the molecule and water is higher than the strength of interaction among the solute molecules then the solute dissolves. (Also have a look at this post). Phospholipid is an amphipathic molecule — it has both hydrophobic and hydrophilic parts ...