plasma membrane
Americannoun
Usage
What is a plasma membrane? Plasma membrane is another term for the cell membrane—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 plasma membrane. In general, a membrane is a thin barrier or covering. In the context of biology, plasma is used as another word for cytoplasm. 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 plasma 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 plasma membrane. The plasma membrane is also called the plasmalemma.
Etymology
Origin of plasma membrane
First recorded in 1895–1900
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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.
From earlier research, the scientists knew that Rnf43 on its own was not sufficient to break down the Wnt receptor Frizzled, which sits in the plasma membrane.
From Science Daily ● Nov. 24, 2023
Free cholesterol is drawn into the cell's plasma membrane -- the external boundary of the cell -- by a protein called NPC1L1.
From Science Daily ● Nov. 9, 2023
Four of the compounds -- including two of the newly identified ones -- were effective at destroying the plasma membrane of this fungus, causing its cells to leak and preventing it from forming biofilms.
From Science Daily ● Oct. 25, 2023
The solution to moving polar substances and other substances across the plasma membrane rests in the proteins that span its surface.
From Textbooks ● Apr. 25, 2013
The plasma membrane must be sufficiently flexible to allow certain cells, such as red blood cells and white blood cells, to change shape as they pass through narrow capillaries.
From Textbooks ● Apr. 25, 2013
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.
