cell membrane
Americannoun
noun
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The thin membrane that forms the outer surface of the protoplasm of a cell and regulates the passage of materials in and out of the cell. It is made up of proteins and lipids and often contains molecular receptors. The membranes of organelles within the cell are made of the same basic material as the cell membrane. In plant cells, the cell membrane is surrounded by a rigid cell wall.
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Also called plasma membrane
Usage
What is a cell membrane? The cell membrane is the thin layer that encloses a cell’s cytoplasm, which is the substance between the membrane and the nucleus. It allows beneficial things to pass through while blocking harmful ones.The cell is the basic structural unit of all living organisms. It is a microscopic structure consisting of a nucleus surrounded by the cytoplasm and enclosed by a membrane—the cell membrane. In general, a membrane is a thin barrier or covering.The membrane consists of a double layer made up of lipid molecules and large protein molecules. Lipids and proteins are the basic building blocks of living cells. They move fluidly in the cell membrane and function like a system of gates, giving the membrane its ability to allow molecules to pass through. For this reason, the membrane is described as semipermeable (meaning it is capable of allowing things to pass through it).Plants cells also have a rigid outer wall in addition to a cell membrane.The cell membrane is also called the plasma membrane or the plasmalemma.
Etymology
Origin of cell membrane
First recorded in 1865–70
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Inside cells, ions travel through specialized protein channels embedded in the cell membrane.
From Science Daily
Fatty acids are important components of cell membranes in living organisms on Earth, although similar molecules can also form through purely geological reactions under certain conditions.
From Science Daily
Every one of these genes plays a role in either building proteins or moving molecules across cell membranes.
From Science Daily
This first cell membrane created a clear distinction between inside and outside.
From Science Daily
To better understand why this happens, the research team examined a phospholipid called PIP2, which is found in brain cell membranes.
From Science Daily
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.