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Cross-sectional view of the structures that can be formed by phospholipids in an aqueous solution. A biological membrane, biomembrane or cell membrane is a selectively permeable membrane that separates the interior of a cell from the external environment or creates intracellular compartments by serving as a boundary between one part of the cell and another.
This has led many texts to delineate between membrane-bounded and non-membrane bounded organelles. [14] The non-membrane bounded organelles, also called large biomolecular complexes , are large assemblies of macromolecules that carry out particular and specialized functions, but they lack membrane boundaries.
Cellular compartments in cell biology comprise all of the closed parts within the cytosol of a eukaryotic cell, usually surrounded by a single or double lipid layer membrane. These compartments are often, but not always, defined as membrane-bound organelles. The formation of cellular compartments is called compartmentalization.
Light micrograph of a moss's leaf cells at 400X magnification. The following outline is provided as an overview of and topical guide to cell biology: . Cell biology – A branch of biology that includes study of cells regarding their physiological properties, structure, and function; the organelles they contain; interactions with their environment; and their life cycle, division, and death.
The main distinguishing feature of eukaryotes as compared to prokaryotes is compartmentalization: the presence of membrane-bound organelles (compartments) in which specific activities take place. Most important among these is a cell nucleus , [ 2 ] an organelle that houses the cell's DNA .
Embedded in the membrane are proteins that perform the functions of the plasma membrane. The plasma membrane is not a fixed or rigid structure, the molecules that compose the membrane are capable of lateral movement. This movement and the multiple components of the membrane are why it is referred to as a fluid mosaic.
A vacuole (/ ˈ v æ k juː oʊ l /) is a membrane-bound organelle which is present in plant and fungal cells and some protist, animal, and bacterial cells. [ 1 ] [ 2 ] Vacuoles are essentially enclosed compartments which are filled with water containing inorganic and organic molecules including enzymes in solution , though in certain cases ...
The cytoplasm, the cytoplasmic membrane and the cell wall are subcellular localizations, whereas the extracellular environment is clearly not. Most Gram-negative bacteria also contain an outer membrane and periplasmic space. Unlike eukaryotes, most bacteria contain no membrane-bound organelles, however there are some exceptions (i.e ...