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Cell membrane
Make it clearer
The cell membrane, also called the plasma membrane, is the lining that wraps around the outside of the cell. It does two things that sound like opposites: it separates the cell from everything around it and, at the same time, lets materials enter and leave.
That membrane is not a solid sheet. It is built as a lipid bilayer, meaning two layers of fat set against each other, and that architecture has been firmly established as the universal basis for the membranes of all cells.
The reason they settle that way lies in the lipids themselves. All of them are amphipathic, a word that means they have two ends with opposite preferences: one hydrophilic, which seeks water, and one hydrophobic, which avoids it. The ends that seek water end up facing out on both sides, and the ends that avoid it tuck away in the middle.
In brief
The plasma membrane is the outer lining of the cell: it separates the cell from its environment and at the same time allows materials to enter and leave.
Its architecture consists of a lipid bilayer, which is firmly established as the universal basis for cell membrane structure.
All the lipid molecules in those membranes are amphipathic: they have a hydrophilic, water-loving end and a hydrophobic, water-fearing one.
Sources (2)
- MedlinePlus GeneticsWhat is a cell?
- National Center for Biotechnology InformationThe Lipid Bilayer. Molecular Biology of the Cell, 4th editionPublished
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