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A dopamine molecule consists of a catechol structure (a benzene ring with two hydroxyl side groups) with one amine group attached via an ethyl chain. [14] As such, dopamine is the simplest possible catecholamine, a family that also includes the neurotransmitters norepinephrine and epinephrine. [15]
The biological membrane is made up of lipids with hydrophobic tails and hydrophilic heads. [6] The hydrophobic tails are hydrocarbon tails whose length and saturation is important in characterizing the cell. [7] Lipid rafts occur when lipid species and proteins aggregate in domains in the membrane. These help organize membrane components into ...
The hydrophobic effect represents the tendency of water to exclude non-polar molecules. The effect originates from the disruption of highly dynamic hydrogen bonds between molecules of liquid water. Polar chemical groups, such as OH group in methanol do not cause the hydrophobic effect.
A transmembrane domain (TMD, TM domain) is a membrane-spanning protein domain.TMDs may consist of one or several alpha-helices or a transmembrane beta barrel.Because the interior of the lipid bilayer is hydrophobic, the amino acid residues in TMDs are often hydrophobic, although proteins such as membrane pumps and ion channels can contain polar residues.
Fluid mosaic model of a cell membrane. The fluid mosaic model explains various characteristics regarding the structure of functional cell membranes.According to this biological model, there is a lipid bilayer (two molecules thick layer consisting primarily of amphipathic phospholipids) in which protein molecules are embedded.
Illustration of a eukaryotic cell membrane Comparison of a eukaryotic vs. a prokaryotic cell membrane. The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extracellular space).
The nature of biological membranes, especially that of its lipids, is amphiphilic, as they form bilayers that contain an internal hydrophobic layer and an external hydrophilic layer. This structure makes transport possible by simple or passive diffusion , which consists of the diffusion of substances through the membrane without expending ...
The lipophilic group is typically a large hydrocarbon moiety, such as a long chain of the form CH 3 (CH 2) n, with n > 4. The hydrophilic group falls into one of the following categories: [citation needed] charged groups anionic. Examples, with the lipophilic part of the molecule represented by R, are: carboxylates: RCO 2 −; sulfates: RSO 4 −