Level of life
Cell
The smallest unit that can live on its own. Every living thing is made of one or more cells.
Cell membrane
Controls what enters and leaves the cell.Source: NHGRISource: Alberts et al., 2002Source: Neher & Sakmann, 1976
Step 2 of 7ReadingStructure
Inside the cell: cell membrane
The cell membrane is a thin, flexible boundary around the cell. It lets some things in and out and keeps others where they belong.
The membrane is a double layer of lipids studded with proteins. Small uncharged molecules can slip through, but ions and larger molecules need channels, carriers or pumps. Receptor proteins let the cell detect signals from outside.
Phospholipids self-assemble into a bilayer with water-avoiding tails inward. Embedded proteins move laterally in this fluid layer. Channels let specific ions flow down their gradients, while pumps such as the sodium-potassium ATPase spend ATP to move ions against them, setting up the voltage that neurons use to signal.
- Structure
A lipid bilayer with embedded and attached proteins, cholesterol, and sugar chains on the outer surface.
- Key molecules
- Phospholipids
- Cholesterol
- Ion channels
- Pumps
- Receptors
Related health conditions
- Cystic fibrosis. The CFTR protein is a channel in the membrane of cells lining the airways and other organs that moves chloride ions. Variants in CFTR disrupt this channel, which affects the salt and water balance of mucus.Source: MedlinePlusSource: MedlinePlus
For learning only, not medical advice.
How Cell membrane connects
Cell membrane is part of
Cell membrane includes
Molecule
Ion channel
A protein pore that lets particular ions cross a membrane. Single channels can be recorded opening and closing.
Cell membrane is related to
Health condition
Cystic fibrosis
An inherited condition caused by variants in the CFTR gene, in which thick mucus damages the lungs, digestive system and other organs.
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Sources & further reading
The explanations on this page are our own summaries of these sources. Follow a link to read the original; if anything here disagrees with it, the original wins. How we choose and check sources.
Cell Membrane (Plasma Membrane) (opens the original in a new tab)
National Human Genome Research Institute. Talking Glossary of Genomic and Genetic Terms. National Human Genome Research Institute, NIH.
ReferenceGovernment sourceEducationalMolecular Biology of the Cell (4th edition) (opens the original in a new tab)
Alberts B, Johnson A, Lewis J, et al. (2002). Garland Science.
Free to read on NCBI Bookshelf. Standard reference for cell structure and molecular biology.
TextbookEducationalSingle-channel currents recorded from membrane of denervated frog muscle fibres (opens the original in a new tab)
Neher E, Sakmann B (1976). Nature 260:799-802.
Peer-reviewedPrimary researchThe structure of the potassium channel: molecular basis of K+ conduction and selectivity (opens the original in a new tab)
Doyle DA, Morais Cabral J, Pfuetzner RA, et al. (1998). Science 280:69-77.
Peer-reviewedPrimary researchCystic fibrosis (opens the original in a new tab)
MedlinePlus Genetics. MedlinePlus Genetics. U.S. National Library of Medicine, NIH.
ReferenceGovernment sourceEducationalCFTR gene (opens the original in a new tab)
MedlinePlus Genetics. MedlinePlus Genetics. U.S. National Library of Medicine, NIH.
ReferenceGovernment sourceEducational