Cell walls and cell membranes are both crucial components of cells, but they differ significantly in structure, composition, and function. Here are five key distinctions:
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Presence and Location: Cell walls are found only in plants, fungi, algae, and most bacteria, situated outside the cell membrane. Animal cells lack a cell wall. Conversely, the cell membrane (also known as the plasma membrane) is found in all cells, forming the outermost boundary in animal cells and residing inside the cell wall in plant and other cells with a cell wall. [Reference: Byjus.com, GeeksforGeeks, Tutoroot.com]
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Rigidity and Flexibility: Cell walls are rigid structures, providing structural support and maintaining the cell's shape. The cell membrane, in contrast, is flexible and can change shape and size depending on the cell's needs. [Reference: Byjus.com (Dec 2023), GeeksforGeeks]
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Composition: Cell walls are primarily composed of carbohydrates, such as cellulose in plants and chitin in fungi, while the cell membrane consists of a phospholipid bilayer embedded with proteins and other molecules. The composition varies depending on the organism. [Reference: Byjus.com, Nature.com]
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Permeability: Cell walls are generally more permeable than cell membranes. They allow the passage of many molecules and provide structural support. The cell membrane, however, acts as a selective barrier, regulating the transport of substances into and out of the cell through specialized channels and pumps. [Reference: Implicit in the definition of their functions across references]
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Function: While both contribute to cell protection, their roles differ. The cell wall offers primary structural support and protection against mechanical stress and pathogens. The cell membrane's main function is to regulate the movement of substances, maintain cell integrity and participate in cell signaling. [Reference: Byjus.com, Genome.gov, PMC]
