4. Membrane lipids are amphipathic and form ordered structures spontaneously in water 4.1 All membrane lipids contain a polar (hydrophilic) head and a nonpolar(hydrophobic) tail 4.1.1 Membrane lip oias are usua represented by a circle head and one or two attached wavy or straight lines as the tails. 4.2 The amphipathic membrane lipids form ordered structures in water 4.2.1 Amphipathic lipids form oriented monolayers at air-water interfaces (experiment?)
4. Membrane lipids are amphipathic and form ordered structures spontaneously in water 4.1 All membrane lipids contain a polar (hydrophilic) head and a nonpolar (hydrophobic) tail. 4.1.1 Membrane lipids are usually represented by a circle head and one or two attached wavy or straight lines as the tails. 4.2 The amphipathic membrane lipids form ordered structures in water. 4.2.1 Amphipathic lipids form oriented monolayers at air-water interfaces. (experiment?)
4.2.2 Fatty acids, lysophospholipids (glycerophospholipids lacking one fatty acyl group) forms the globular micelles in water 4.2.3 Phospholipids and glycolipids in aqueous media favorably form bimolecular sheets (lipid bilayers) rather than micelles. This is because the two fatty acyl tails are too bulky to fit into the interior of a micelle (cylindrical- -shaped versus wedge-shaped)
4.2.2 Fatty acids, lysophospholipids (glycerophospholipids lacking one fatty acyl group) forms the globular micelles in water. 4.2.3 Phospholipids and glycolipids in aqueous media favorably form bimolecular sheets (lipid bilayers) rather than micelles. This is because the two fatty acyl tails are too bulky to fit into the interior of a micelle. (cylindrical-shaped versus wedge-shaped)
4.2. 4 The formation of lipid bilayers from phospholipids and glycolipids is rapid and pl spontaneous, sta bilized by the full array of weak interactions 4.2.5 Lipid bilayers have an inherent tendency to be extensive (due to diffusion? function? ) 4.2.6 Lipid bilayers tend to close themselvesto limit the amount exposed hydrocarbon chains), generating artificial structures calle d liposomes
4.2.4 The formation of lipid bilayers from phospholipids and glycolipids is rapid and spontaneous, stabilized by the full array of weak interactions. 4.2.5 Lipid bilayers have an inherent tendency to be extensive (due to diffusion? function?). 4.2.6 Lipid bilayers tend to close themselves (to limit the amount exposed hydrocarbon chains), generating artificial structures called liposomes
4.2.7Li ipid bilayers are self-sealing because a hole in a bila yer is energetically unfavorable (driven by hydrophobic interaction and diffusion) 4.3 Liposomes can be used to carry membrane impermeable substances into cells 43. 1 Water-Soluble substances(e.g. proteins, nucleic acids, drugs) can be encapsulated into liposomes. 4.3.2 Liposomes can fuse with cell plasma membranes(a lipid bilayer), releasing substances into cells(can be used as drug delivery tools). 4.3.3 Liposomes are used as model systems to study membrane permeability (or membrane protein reconstitution)
4.2.7 Lipid bilayers are self-sealing because a hole in a bilayer is energetically unfavorable (driven by hydrophobic interaction and diffusion). 4.3 Liposomes can be used to carry membrane impermeable substances into cells. 4.3.1 Water-soluble substances (e.g., proteins, nucleic acids, drugs) can be encapsulated into liposomes. 4.3.2 Liposomes can fuse with cell plasma membranes (a lipid bilayer), releasing substances into cells (can be used as drug delivery tools). 4.3.3 Liposomes are used as model systems to study membrane permeability (or membrane protein reconstitution)
Aqueous Individual units are cavit Individual units are (cross-section of head lindrical (cross-section of p greater than that head equals that of side chain) of side chain) Micelle Bilayer Liposome (a) (b)