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Glycolipids: Any compound containing one or more monosaccharide residues bound by a glycosidic linkage to a hydrophobic moiety such as an acylglycerol (see Glycerides), a sphingoid, a ceramide (Ceramides) (N-acylsphingoid) or a prenyl phosphate. (From Iupac's webpage)

What are Membranes?

JoVE 10971

A key characteristic of life is the ability to separate the external environment from the internal space. To do this, cells have evolved semi-permeable membranes that regulate the passage of biological molecules. Additionally, the cell membrane defines a cell’s shape and interactions with the external environment. Eukaryotic cell membranes also serve to compartmentalize the internal space into organelles, including the endomembrane structures of the nucleus, endoplasmic reticulum and Golgi apparatus. Membranes are primarily composed of phospholipids composed of hydrophilic heads and two hydrophobic tails. These phospholipids self-assemble into bilayers, with tails oriented toward the center of the membrane and heads positioned outward. This arrangement allows polar molecules to interact with the heads of the phospholipids both inside and outside of the membrane but prevents them from moving through the hydrophobic core of the membrane. Proteins and carbohydrates contribute to the unique properties of a cell’s membrane. Integral proteins are embedded in the membrane, while peripheral proteins are attached to either the internal or external surface of the membrane. Transmembrane proteins are integral proteins that span the entire cell membrane. Transmembrane receptor proteins are important for communicating messages from the outside to the ins

 Core: Biology

The Fluid Mosaic Model

JoVE 10698

The fluid mosaic model was first proposed as a visual representation of research observations. The model comprises the composition and dynamics of membranes and serves as a foundation for future membrane-related studies. The model depicts the structure of the plasma membrane with a variety of components, which include phospholipids, proteins, and carbohydrates. These integral molecules are loosely bound, defining the cell’s border and providing fluidity for optimal function. The most abundant component of the fluid mosaic model is lipids. Lipids include both phospholipids and cholesterols. Phospholipids are amphipathic, having both hydrophobic and hydrophilic parts. They consist of a hydrophilic—water-loving—head, and two hydrophobic—water-fearing—fatty acid tails. Phospholipids spontaneously form a lipid bilayer that separates the inside of the cell from the outside. The lipid bilayer consists of the hydrophobic tails facing inward and the hydrophilic heads facing the aqueous environment inside and outside the cell. Cholesterols are a class of steroids that play a role in regulating membrane fluidity and flexibility. Membrane fluidity facilitates the transport of specific molecules and ions across the plasma membrane. The second major component of the mosaic is proteins. Proteins can differentially associate with the li

 Core: Biology
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