Phospholipids are a family of lipids similar in structure to triacylglycerols they include glycerophospholipids and sphingomyelin Glycerol PO 4 Amino alcohol Fatty acid Fatty acid ID: 591375
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17.5 Phospholipids
Phospholipids are a family of lipids similar in structure to triacylglycerols; theyinclude glycerophospholipids and sphingomyelin.
Glycerol
PO
4
Amino
alcohol
Fatty acid
Fatty acid
Learning
Goal
Draw the structure of a phospholipid containing glycerol or sphingosine.
GlycerophospholipidSlide2
Glycerophospholipids
Glycerophospholipids containtwo fatty acids that form ester bonds with the first and second hydroxyl groups of glycerol.a hydroxyl group that forms an ester with phosphoric acid, which forms another phosphoester bond with an amino alcohol.PO4Amino alcohol
Fatty acid
Fatty acid
GlycerolSlide3
Sphingomyelin
Sphingomyelincontains sphingosine instead of glycerol.contains a fatty acid, phosphate, and an amino alcohol.PO4Amino alcohol
Fatty acid
SphingosineSlide4
Amino Alcohols
Amino alcohols found in glycerophospholipids are choline, serine, and ethanolamine.are ionized at physiological pH of 7.4.Slide5
Lecithin and Cephalin
Lecithin and cephalin are two types of glycerophospholipids that areabundant in brain and nerve tissues.found in egg yolk, wheat germ, and yeast.Slide6
General, Organic, and Biological Chemistry: Structures of Life,
5/eKaren C. Timberlake © 2016 Pearson Education, Inc.Structure and Polarity of a Glycerophospholipid
Glycerophospholipids
contain both polar and nonpolar regions that allow them to interact with polar and nonpolar substances.
have a
polar head
containing the ionized amino alcohol and phosphate portion, which is strongly attracted to water.
have a nonpolar
hydrocarbon tail portion soluble only in nonpolar substances such as lipids.Slide7
General, Organic, and Biological Chemistry: Structures of Life,
5/eKaren C. Timberlake © 2016 Pearson Education, Inc.Structure and Polarity of a Glycerophospholipid
(a)
The components of a typical glycerophospholipid: an
amino alcohol, phosphoric acid, glycerol, and two fatty acids. (b) In
a glycerophospholipid, a polar “head” contains the ionized amino alcohol and
phosphate, while the hydrocarbon chains of two fatty acids make up the nonpolar “tails.” (c)
A simplified drawing indicates the polar region and
the nonpolar region.Slide8
Glycerophospholipid, Snake Venom
The venom of the eastern diamondback rattlesnake and the Indian cobra contains phospholipases, which are enzymes that catalyze the hydrolysis of the fatty acid on the center carbon of glycerophospholipids in the red blood cells.produces a lysophospholipid, which causes the breakdown of the red blood cell membranes.Slide9
Study Check
Draw the condensed structural formula for the cephalin that contains two stearic acids, phosphate, and serine as the ionized amino alcohol.Slide10
Solution
Draw the condensed structural formula for the cephalin that contains two stearic acids, phosphate, and serine as the ionized amino alcohol.ANALYZE Given NeedTHE cephalin, two stearic condensed PROBLEM acids (18:0), phosphate, structural serine (ionized) formulaSlide11
Solution
Draw the condensed structural formula for the cephalin that contains two stearic acids, phosphate, and serine as the ionized amino alcohol.Slide12
Study Check
Identify each of the following as a fatty acid, triacylglycerol, amino alcohol, or glycerophospholipid: A. glyceryl trioleate B. cephalin C. choline D. palmitic acidSlide13
Solution
Identify each of the following as a fatty acid, triacylglycerol, amino alcohol, or glycerophospholipid: A. glyceryl trioleate triacylglycerol B. cephalin glycerophospholipid C. choline amino alcohol D. palmitic acid fatty acidSlide14
Sphingomyelin
Sphingomyelin containssphingosine, a long-chain amino alcohol that replaces glycerol.an amide bond formed by the amine group on sphingosine to a fatty acid.a hydroxyl group that forms an ester bond with phosphate, which forms another phosphoester bond to choline or ethanolamine.Slide15
Sphingomyelin
Sphingomyelins are abundant in the white matter of the myelin sheath, a coating surrounding the nerve cells that increases the speed of nerve impulses and insulates and protects the nerve cells.In multiple sclerosis, sphingomyelin is lost from the myelin sheath, which protects the neurons in the brain and spinal cord.the myelin sheath deteriorates as the disease progresses.scars form on the neurons and impair the transmission of nerve signals.Slide16
Sphingomyelin
Structure of a sphingomyelin containing myristic acid and choline. Slide17
Study Check
Palmitic acid, the 16-carbon saturated fatty acid, is the most common fatty acid found along with the ionized amino alcohol choline in the sphingomyelin of eggs. Draw the condensed structural formula for this sphingomyelin.Slide18
Solution
Palmitic acid, the 16-carbon saturated fatty acid, is the most common fatty acid found along with the ionized amino alcohol choline in the sphingomyelin of eggs. Draw the condensed structural formula for this sphingomyelin.ANALYZE Given NeedTHE sphingomyelin, condensed PROBLEM palmitic acid (16:0), structural choline (ionized) formulaSlide19
Solution
Palmitic acid, the 16-carbon saturated fatty acid, is the most common fatty acid found along with the ionized amino alcohol choline in the sphingomyelin of eggs. Draw the condensed structural formula for this sphingomyelin.