Transcript Lipids - CHEM225

Chapter 15 Lipids
1
15.5
Glycerophospholipids
Fatty acid
Glycerol
Fatty acid
PO4
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Amino
alcohol
Copyright © 2012 by Pearson Education, Inc.
Glycerophospholipids
2
Glycerophospholipids are
• the most abundant lipids in cell membranes
• composed of glycerol, two fatty acids, phosphate, and an
amino alcohol
Fatty acid
Glycerol
Fatty acid
PO4
Amino
alcohol
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Polarity of Glycerophospholipids
3
Amino alcohols found in glycerophospolipids
• have two nonpolar fatty acid chains, a phosphate group, and a
polar amino alcohol
• are ionized at physiological pH of 7.4
CH3
+
+
HO−CH2−CH2−N−CH3
Choline
CH3
HO−CH2−CH2−NH3
+
Ethanolamine
NH3
HO−CH2−CH−COO− Serine
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Lecithin and Cephalin
4
Lecithin and cephalin are types of glycerophospholipids that are
• abundant in brain and nerve tissues
• found in egg yolk, wheat germ, and yeast
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Structure and Polarity of a
Glycerophospholipid
5
Glycerophospholipids
• have 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 hydrocarbon tail portion only soluble in nonpolar
substances such as lipids
• are the most abundant lipids in cell membranes and play an
important role in cellular permeability
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Structure and Polarity of a
Glycerophospholipid
6
(a) In a glycerophospholipid, a polar head contains
the ionized amino alcohol and phosphate groups,
while the two fatty acids make up the nonpolar tails.
(b) A simplified drawing indicates the polar region
and the nonpolar region.
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Learning Check
7
Identify each of the following as a fatty acid, triacylglycerol,
amino alcohol, or glycerophospholipid.
A. glyceryl trioleate
B. cephalin
C. choline
D. palmitic acid
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Solution
8
Identify each of the following as a fatty acid, triacylglycerol,
amino alcohol, or glycerophospholipid.
A. glyceryl trioleate
B. cephalin
triacylglycerol
glycerophospholipid
C. choline
D. palmitic acid
amino alcohol
fatty acid
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Learning Check
9
Draw the condensed structural formula of a cephalin that contains
stearic acid and serine.
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.
Solution
10
Draw the condensed structural formula of a cephalin that contains
stearic acid and serine.
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition
Copyright © 2012 by Pearson Education, Inc.