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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.
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.
Mitochondria are surrounded by two membranes; the inner and outer mitochondrial membranes. These two membranes allow the formation of two aqueous compartments, which are the intermembrane space (IMS) and the matrix. [2] Channel proteins called porins in the outer membrane allow free diffusion of ions and small proteins about 5000 daltons or ...
Illustration of a eukaryotic cell membrane Comparison of a eukaryotic vs. a prokaryotic cell membrane. The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extracellular space).
The numerous invaginations of the membrane are called cristae, separated by crista junctions from the inner boundary membrane juxtaposed to the outer membrane. Cristae significantly increase the total membrane surface area compared to a smooth inner membrane and thereby the available working space for oxidative phosphorylation.
1 Outer membrane. 1.1 Porin. 2 Intermembrane space. 2.1 Intracristal space 2.2 Peripheral space. 3 Lamella. 3.1 Inner membrane 3.11 Inner boundary membrane 3.12 Cristal membrane 3.2 Matrix You are here 3.3 Cristæ. 4 Mitochondrial DNA 5 Matrix granule 6 Ribosome 7 ATP synthase
The nuclear envelope is made up of two lipid bilayer membranes, an inner nuclear membrane and an outer nuclear membrane. These membranes are connected to each other by nuclear pores. Two sets of intermediate filaments provide support for the nuclear envelope. An internal network forms the nuclear lamina on the inner nuclear membrane. [7]
The first proposal that the membranes within cells form a single system that exchanges material between its components was by Morré and Mollenhauer in 1974. [19] This proposal was made as a way of explaining how the various lipid membranes are assembled in the cell, with these membranes being assembled through lipid flow from the sites of ...