(L7) Biochemistry: Membrane Structure and Lipids

Non-polar or amphipathic molecules. Biologic origin. Constituents of membranes, fats, oils, waxes & detergents.
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Terms in this set (40)
Non-polar or amphipathic molecules. Biologic origin. Constituents of membranes, fats, oils, waxes & detergents.
Lipids
Polar head group. Glycerol backbone. Fatty acids, the principal hydrophobic component.
Phosphatildylethanolamine
Long chain or branched hydrocarbons, or esters. Hydrophobic solid or semisolid.
Waxes
Hydrophobic liquid. Can be hydrocarbons, triglycerides, or fatty acids of varying length, but can be other chemical types as well.
Oils
In medicine and biology: triglycerides. In a broad context, a hydrophobic solid, or semisolid.
Fat
Natural or synthetic amphiphilic compounds that act as surfactants (form micelles).
Detergents
Essential fatty acid(s)
Linoleic & Linolenic
Fatty acids with only one double bond are called ________________.
Mono-saturated
Fatty acids with two or more double bonds are called __________________.
Poly-unsaturated
The degree of ____________________ affects fluidity of both membrane lipids where fatty acids are constituents, as well as of fat.
Unsaturation
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