Lipids Chapter 11

sphingomyelin

-A sphingophospholipid containing a sphingosine backbone and a phosphate head group. -the amino group of the sphingosine backbone is linked to fatty acids by an amide bond -primary (-OH) of sphingosine is attached to phosphorylcholine through an ester linkage -Found in plasma membranes of cells but rich in myelin sheath of nerve cells

Cis and trans

-Cis: same side of the double bond -Trans opposite side of the double bond

gangloside

-Complex glycolipids that contain branched chain of up to seven sugar residues

phospholipid

-Important constituent of membranes that is composed of three components: 1.) glycerol or sphingosine backbone 2.) two fatty acid chains, and a phosphorylated alcohol

Phosphatidate

-Intermediate of phospholipid synthesis -Different polar head groups can be added to phosphoric acid -Rarely seen in high concentrations in body

cereboside

-Simplest glycolipid -Contains a single sugar residue that is either glucose or galactose

sphingosine

-amino alcohol that contains a long unsaturated hydrocarbon chain -phospholipid built on a sphingosine backbone

Palmitoyl group

-attached to a cysteine residue by thioester bond

Fatty acid

-chains of hydrogen-bearing carbon atoms, hydrocarbons -terminate with carboxylic acid group -Serve as fuel an building blocks for membrain lipids

Linoleic Acid Systematic name

-cis, cis-delta9, delta 12-Octadecadienoic acid -Also known as a n omega-6 fatty acid -naming is n to n+1

Lauric Acid

-common name: Lauric acid or Laurate -systematic name: n-Dodecanoate -12:0 (Number of carbons: number of double bonds) -CH3(CH2)10COOH (formula)

amphipathic molecule

-ex. membrane lipids - containing both hydrophilic and hydrophobic moiety

glycosylphosphatidylinositol (GPI) anchor

-glycolipid structure attached to the carboxyl terminus

Covalent attachments of hydrophobic groups

-lipids can be attached to proteins --> provides additional properties -necessary for a protein to associate with a hydrophobic env't (i.e. membrane) -attachments can insert into the hydrophobic interior of the membrane and localize protein to membrane surface -localization required for protein function

cholesterol

-most common steroid and precursor to biochemically active steroids -member of class of molecules called sterols that contain alcohol functional group.

phosphoglyceride

-phospholipids derived from glycerol -composed of glycerol backbone which are attached to two fatty acid chains and phosphorylated alcohol

triacylglycerol

-storage of fatty acids for energy generation -formed by attach of three fatty acid chains to a glycerol molecule via ester linkages (esterification)

glycolipid

-sugar containing lipids -ubiquitous in all cell membranes -play role in cell-to-cell interactions -derived from sphingosine in animal cells -amino group of sphingosine backbone is acylated by a fatty acid (similar to sphingomyelin) -identiy of the unit that is linked to the primary -OH of the sphingosine backbone has one or more sugars attached (not phosphorylcholine)

Name two properties important for lipid membranes

1. degree of saturation 2. length of hydrocarbon chain

types of lipids

1.) Fatty acids 2.) triacylglycerols 3.) Phospholipds 4.) Glycolipids 5.) Cholesterol/Steroids

Arrange the following fatty acids in order of increasing melting point: -Stearic acid (18:0) -linolenic acid (18:3) -linoleic acid (18:2) -oleic acid (18:1)

1.) Linolenic acid (18:3) 2.) linolenic acid (18:2) 3.) oleic acid (18:1) 4.) stearic acid (18:0)

What lipids are membrane lipids with amphipathic properties?

1.) Phospholipids 2.) Glycolipids 3.) Cholesterols/Steroids

Three attachment styles

1.) palmitoyl group 2.) farnesyl group 3.) Glycosylphosphatidylinositol (GPI) anchor to carboxyl terminus

what are the three types of membrane lipids

1.) phospholipids 2.) glycolipids 3.) cholesterol

Linoleic Acid

Common name

Unsaturated

Contain one or more double or triple bonds

Increasing the van de Waals interactions forms____________________ ___________. As a consequence, this changes the _______________ _____________ (____ ____) of a fatty acid.

Stronger solid, melting temperature (Tm)

melting temperature (Tm)

The temperature at which lipids turn to liquid

Cis and trans configuration can alter what properties of fatty acid

Tm (melting temperature)

Farnesyl group

attached to a cysteine residue at the carboxyl terminus

What is the most natural double bonds:

cis -A kink is formed in the hydrocarbon chain in cis ftty acids

Longer hydrocarbon chains

higher Tm

No double bonds (saturation)

higher Tm

More double bonds (saturation)

lower Tm

shorter hydrocarbon chains

lower Tm

glycolipids are

orientated in an asymmetric fashion in membranes with the sugar residues always on the extracellular side of the membrane

In S-palmitoylcysteine, the palmitoyl group is attached to the cysteine via a(n) _____ bond.

thioester

Cis and trans can change_________________________ and ____________ between tails

van de Waals interactions, packing