(L7) Biochemistry: Membrane Structure and Lipids

Non-polar or amphipathic molecules. Biologic origin. Constituents of membranes, fats, oils, waxes & detergents.
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Saturated fatty acids are the _______________ fluid.LeastFat with high percentage of saturated fat is more _____________; it is also less healthy in the diet.SolidMono-unsaturated fatty acids are more ___________ than saturated FAs, but less so than poly-unsaturated FAs.Fluid__________________ FAs are more fluid than the others, depending on the degree (how many double bonds) and their placement in the hydrocarbon chain.Poly-unsaturatedProduced mostly from chemical hydrogenation of poly- unsaturated oil to alter their physical properties. They can also be produced with prolonged heating of unsaturated or polyunsaturated oils, such as in deep fat fryers (think French fries).Trans-fatty acidsTerm meaning easy to make and break and transfer to other molecules.Labile_________________ are constituted of 1 glycerol and three fatty acyl chains (FA for fatty acid).TriglyceridesGlycerol plus 1 FAs is ____________.MonoAcylGlycerol (MAG)Glycerol plus 2 FAs is ___________.DiAcylGlycerol (DAG)Glycerol plus 3 FAs is _____________.TriAcylGlycerol (TAG or TG).Fatty acids and MAGs can act as ________________. This is an important part of dispersing fat during digestion.DetergentsCells are compartmentalized by ___________.MembranesFirst to reconcile the apparent protein and lipid composition of membranes and illustrated the bilayer nature of cellular membranes.The Singer-Nicholson ModelContain a glycerol backbone. Has two fatty acids, one being in the (2-position) and is typically unsaturated. The end (1) position fatty acid may be saturated.GlycerophospholipidMost common phospholipid.Phosphatidylchline (PC)Principal constituent of bacterial membranes.Phosphatidyl-ethanolamine (PE)Serves as a signal in apoptosis.Phosphatidylserine (PS)A relatively minor constituent in mammalian membranes.Phosphatidyl-inositol (PI)A specialized lipid found principally in the mitochondrial inner membrane. The role of this lipid is to make the membrane more impermeable to ions.CardiolipinCan constitute a substantial percentage of lipids in some membranes (e.g., plasma membranes) and in myelin. They have a similar structure to phospholipids except that the end fatty acyl group has an ether linkage and a double bond rather than the ester linkage found in fat and glycerophospholipids.PlasmalogensType A: Cleaves fatty acids from the glycerol backbone. Type B: Not shown, can cleave fatty acids at either the 1 or 2 positions, usually uses lysophosphatidylcholine as a substrate. Type C: Cleaves the head-group between the glycerol and the phosphate. Type D: Cleaves the head-group after the phosphate.Phospholipases_________________ is important because it is activated through hormone signaling mechanisms. This can release arachidonic acid from PI or PC.Phospholipase A2______________ can release IP3 from PIP2 and generates DAG as well. This is part of hormone second messenger signaling systems.Phospholipase CPI-specific phospholipase C is regulated through ________________.Transmembrane signalingA constituent of many membranes, but more so in neuronal membranes and myelin.SphingomyelinAn important breakdown intermediate.SphingosineServe a role in intercellular communication. They are found on the outer leaflet of the plasma membrane where they interact with the extracellular environment. They play a role in regulation of the cellular interactions, growth and development. They act as antigenic determinants of the ABO blood groups and are also a source of various embryonic antigens important in certain stages of fetal development. They are essential components of all cellular membranes but found in abundance in nerve tissue. They constitute 6% of membrane lipids in gray matter of human brain.GlycosphingolipidsComposes up to 30% of a membrane. Major constituent of lipid bilayer. Can be obtained from the diet or synthesized from Acetyl CoA int eh liver. Modulates fluidity.CholesterolCholesterol modulates membrane fluidity by broadening ____________________.Lipid phase transitionsSome lipids are on both the inner and outer membrane leaflets, while others are confined principally to one or the other. This results in _________.Lipid bilayer asymmetry