S AVA N N A H , A S H L E Y, E R I K A

Chapter 13 Section 13.4-13.8

Section 13.4

What are the Structures of Complex Lipids?Complex Lipids:Complex lipids are important because they constitute the main

components of membranes.Complex lipids can be classified into two groups.

Phospholipids:Contain an alcohol, two fatty acids, and a phosophate groupThere are two types:

Glycerophospholipids have glycerol as the alcohol Sphingolipids have sphingosine as the alcohol

Section 13.4 (cont.)

Glycolipids:These are complex lipids that contains carbohydrates

Section 13.5

What Role Do Lipids Play in the Structure of Membranes?Structure of Complex LipidsComplex lipids form the membranes around body cells

and around small structures inside the cells. These membranes are made up of lipid bilayers Unsaturated fatty acids are important components

because they prevent the tight packing of the hydrophobic chains in the lipid bilayers

Section 13.5 (cont.)

The fluid mosaic model of membranes allows the passage of nonpolar compounds by diffusion. These compounds are soluble in the lipids membranes.

Section 13.6

What are Glycerophospholipids? Similar structure to fats Membrane components throughout the body Alcohol is glycerol 2 out of 3 groups are esterified by fatty acids

The third group is esterfied by a phosphate group, which is also esterfied to another alcohol If the other alcohol is choline, a quarternary ammonium compound,

the glycerophospholipids are called phosphatidylcholines (lecithin)

Section 13.6 (cont.)

May be long-chain carboxlyic acids, with or without double bonds In glycerophospholipids, lecithins, caphalins, and

phosphatidylinositols, the fatty acid on carbon 2 of glycerol is ALWAYS unsaturated

Section 13.6 (cont.)Lecitin

Stearic acid on one end and linoleic acid in the middle

Others contain other fatty acids, but the one on the end is always saturated and the one in the middle is always unsaturated

Major compo nent of egg yolk

Section 13.6 (cont.)

Includes both polar and nonpolar portions all within one molecule Excellent emulsifier

Used in mayonnaise Negitively charged phosphate group Positively charged quaternary nitrogen from the choline Hydrophilic head, rest is hydrophobic

Section 13.6 (cont.)

Cephalins Similar to lecithins in every way except for having other alcohols

such as ethanolamine or serine instead of cholinePhosphatidylinositols (PI)

Alcohol insolitol is bonded to the rest of the molecule by a phosphate ester bond

Have higher forms such as phosphatidylinositol 4,5-bisphosphates (PIP2) Serve as signaling molecules in chemical communication

Section 13.7

What are Sphingolipids ?

The different complex lipids found in the nerve axons coating, Myelin

Not randomly distributed in membranes Example

Viral membranes appear on the inside

Section 13.7 (cont.)

Alcohol portion is Sphingosine

Long –chain fatty acid Connected by –NH₂ by amide bond -OH group is on the other end

Setions 13.7 (cont.)

Ceramide Fatty acid combined with sphingosine

Colored part Complex lipids – many different fatty acids

Section 13.7 (cont.)

Sphingomyelins Most important lipids in the myelin sheaths

Johann Thudichum Discovered in 1874 Named them after Greek

mythology monster - Sphink

Section 13.8

What Are Glycolipids?

Complex lipids Made up of Carbohydrates and ceramides

Section 13.8 (cont.)

Cerebrosides is made up of mono- or oligosaccha of ceramide 18-carbon or 24- carbon chains Primarily in the brain Nerve synapses

Glangliosides are made up of more complex carbohydrate structure