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L I P I D S II. Simple Lipids. Neutral fats and oils Monoacyl glycerols (monoglycerides) Diacyl glycerols (diglycerides) Triacyl glycerols (triglycerides) Triglycerides found in seeds and animal adipose tissue Triacyl glycerols (triglycerides) Lipid storage form
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Simple Lipids • Neutral fats and oils • Monoacyl glycerols (monoglycerides) • Diacyl glycerols (diglycerides) • Triacyl glycerols (triglycerides) • Triglycerides found in seeds and animal adipose tissue • Triacyl glycerols (triglycerides) • Lipid storage form • Where in the body? Adipocytes!! • Most lipids consumed are triglycerides
I- Triglycerides • Most common structure in dietary lipids • Composed of one glycerol molecule and three fatty acids connected by an ester bond (bond between an alcohol and and organic acid) • Fatty acids may be same or mixed Fatty Acid Fatty Acid Glycerol Fatty Acid
II- Waxes • Waxes are also esters like fats • Use one alcohol instead of glycerol • Esters of: • Long-chain fatty acid • Long-chain alcohol • The longer the chains, the higher the melting point • Protects the skin of plants and fur of animals • Examples of waxes include: • Carnuba, from Brasilian wax palm • Beeswax
Complex Lipids -Phospholipids • Two primary types: • Glycerophosphatides • Backbone structure is glycerol • Part of cell membranes, chylomicrons, lipoproteins • Sphingophosphatides • Backbone structure is sphingosine • Part of sphingomyelin
Glycerophospholipids(phosphoglycerides), are common constituents of cellular membranes. They have a glycerol backbone. Hydroxyls at C1 & C2 are esterified to fatty acids. The C3 hydroxyl is esterified to Pi Glycerophospholipids
Glycerophospholipids In most glycerophospholipids (phosphoglycerides), Pi is in turn esterified to OH of a polarhead group (X): e.g., serine, choline, ethanolamine, glycerol, or inositol. The 2 fatty acids tend to be non-identical. They may differ in length and/or the presence/absence of double bonds.
Phosphatidylinositol: • With inositol as polar head group, is one glycerophospholipid. • In addition to being a membrane lipid, phosphatidylinositol has roles in cell signaling.
Phosphatidylcholine (Lecithin): • With choline as polar head group. • It is a common membrane lipid.
Each glycerophospholipid includes • a polar region: glycerol, carbonylO of fatty acids, Pi, & the polar head group (X) • non-polar hydrocarbon tails of fatty acids (R1, R2).
Phospholipids … • Significant use in feed industry as emulsifiers • Lipids form emulsion in water • Phospholipid sources: • Liver, egg yolk, • Soybeans, wheat germ • Peanuts
Sphingolipids: are derivatives of the lipid sphingosine, which has a long hydrocarbon tail, and a polar domain that includes an amino group. The amino group of sphingosine can form an amide bond with a fatty acid carboxyl, to yield a ceramide. In the more complex sphingolipids, a polar “head group" is esterified to the terminal hydroxyl of the sphingosine moiety of the ceramide.
Sphingomyelin has a phosphocholine or phosphethanolamine head group. Sphingomyelins are common constituent of plasma membranes Sphingomyelin, with a phosphocholine head group, is similar in size and shape to the glycerophospholipid phosphatidyl choline.
Complex Lipids - Glycolipids • Carbohydrate component in structure • Cerebrosides & gangliosides • Medullary sheaths of nerves; white matter of brain
A cerebroside is a sphingolipid (ceramide) with a monosaccharide such as glucose or galactose as polar head group. A ganglioside is a ceramide with a polar head group that is a complex oligosaccharide, including the acidic sugar derivative sialic acid. Cerebrosides and gangliosides, collectively called glycosphingolipids, are commonly found in the outer leaflet of the plasma membrane bilayer.
Cardiolipids A polyglycerol phospholipid; makes up 15% of total lipid-phosphorus content of the myocardium – associated with the cell membrane Cardiolipids are antigenic and as such are used in serologic test for syphilis (Wasserman test).
PL GL TAG GPL SL SL FA S FA FA C MS/OS P A TAG: triacylglycerol PL: phospholipids GPL: glycerophospholipid G: glycerol FA: fatty acid P: phosphate A: alcohol SL: sphingolipid C: choline GL: glycolipid S: sphingosine MS/OS: monosaccharide/oligosaccharide Storage (neutral) Membrane (polar) G FA P
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