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An example of these amphiphilic molecules is the lipids that comprise the cell membrane. Another example is soap, which has a hydrophilic head and a hydrophobic tail, allowing it to dissolve in both water and oil. Hydrophilic and hydrophobic molecules are also known as polar molecules and nonpolar molecules, respectively. Some hydrophilic ...
The hydrophilic end usually contains a negatively charged phosphate group, and the hydrophobic end usually consists of two "tails" that are long fatty acid residues. [ 4 ] In aqueous solutions, phospholipids are driven by hydrophobic interactions , which result in the fatty acid tails aggregating to minimize interactions with the water molecules.
The phosphate ester portion ("head") is hydrophilic, whereas the remainder of the molecule, the fatty acid "tail", is hydrophobic. These are important components for the formation of lipid bilayers. Phosphatidylethanolamines, phosphatidylcholines, and other phospholipids are examples of phosphatidates.
An example of a carrier ionophore is valinomycin, a molecule that transports a single potassium cation. Carrier ionophores may be proteins or other molecules. Channel formers that introduce a hydrophilic pore into the membrane, allowing ions to pass through without coming into contact with the membrane's hydrophobic interior. [8]
[21] [22] They are made of a hydrocarbon chain that terminates with a carboxylic acid group; this arrangement confers the molecule with a polar, hydrophilic end, and a nonpolar, hydrophobic end that is insoluble in water. The fatty acid structure is one of the most fundamental categories of biological lipids and is commonly used as a building ...
This property can be utilized to load liposomes with hydrophobic and/or hydrophilic molecules, a process known as encapsulation. [18] Typically, liposomes are prepared in a solution containing the compound to be trapped, which can either be an aqueous solution for encapsulating hydrophilic compounds like proteins, [ 19 ] [ 20 ] or solutions in ...
The proteins and lipids that make up the surfactant have both hydrophilic and hydrophobic regions. By adsorbing to the air-water interface of alveoli, with hydrophilic head groups in the water and the hydrophobic tails facing towards the air, the main lipid component of the surfactant, dipalmitoylphosphatidylcholine (DPPC), reduces surface tension.
Sterols have a hydrophobic four-membered fused ring rigid structure, and a small polar head group. Cholesterol is bio-synthesised from mevalonate via a squalene cyclisation of terpenoids . Cell membranes require high levels of cholesterol – typically an average of 20% cholesterol in the whole membrane, increasing locally in raft areas up to ...