Lipids

Question 1

Fatty acid nomenclature: 20:5(delta5,8,11,14,17)

Answer 1

20 carboned chain, with 5 double bonds starting at carbons 5, 8, 11, 14, 17 (closest to the carboxy end)

Question 2

As chain length increases, what happens to solubility and MP?

Answer 2

Solubility decreases
MP increases
(MP decreases as number of double bonds increase)

Question 3

Natural unsaturated FA are typically in what form?

Answer 3

Cis

Question 4

Melting point with double bonds

Answer 4

Melting point decreases as the number of double bonds increase
because the FA aren’t packed in a nice tight way, so it takes less thermal energy to break them

Question 5

Why are trans fatty acids bad?

Answer 5

Increase inflammatory diseases

Lowers HDLs and increases LDLs

Question 6

Triacylglycerols (5 main points)

Answer 6

Majority of FA in biological systems
Solid is fat, liquid is oil
Primary storage form is body fat
Fats and oils float
No carboxy group = less soluble

Question 7

Advantage of fats over polysaccharides

Answer 7

FA carry more energy and less water

Also meant for long term energy needs

Question 8

Structure of glycerophospholipids

Answer 8

3 glycerol connecting sat FA, unsat FA are connected to C2, polar head group substitute the “X”

Membrane lipids

Question 9

Phosphatidylcholine

Answer 9

A glycerophospholipid

Major component of euk cell membs

Question 10

Plasmalogen

Answer 10

Vinyl ether
Found in vertebrate heart tissue, protozoa and anaerobic bacteria
Function unknown

Question 11

Plasmalogen structure

Answer 11

Triglycerol with ether linked alkene, ester linked carboxylic acid chain, ethanolamine

Question 12

Structure of platelets activating factor

Answer 12

Triglycerol with ether linked alkane, acetyl-ester, phosphphate-choline

Question 13

What do platelets activating factors do?

Answer 13

First signaling lipid
Stimulates aggregation of blood platelets
Mediation of inflammation

Question 14

Sphingolipids

Answer 14

Backbone is sphingosine
FA joined via amide link, not ester
Found outside of plasma membranes

Question 15

Sphingomyelin

Answer 15

Phosphocholine attached to alcohol

Myelin sheath that surrounds nerve cells

Question 16

Properties of steroids

Answer 16

4 rings (one 5C)
Planar
Polar OH head group
Alkyl side chain

Question 17

Role of cholesterol

Answer 17

Change membrane fluidity and permeability, thicken plasma memb
Bacteria lack sterols
Can bind to proteins to travel through blood stream (LDL=bad)
Hormones are derivatives of sterols

Question 18

Biologically active lipids can

Answer 18

Signal molecules bt nearby cells

Can be soluble vitamins like A, D, E, K

Question 19

Biological functions of lipids

Answer 19

Energy storage
Insulation from environment
Water repellant
Buoyancy and acoustics for marine animals
Membrane structure
Cofactors
Signaling molecules
Pigments
Antioxidants