Lecture 04

Question 1

What are the 2 major families of lipids?

Answer 1

Fatty acids and isoprenes

Question 2

Name the 3 categories of fatty acids

Answer 2

Glycerolipids, sphingolipids, and eiconisoids

Question 3

Name examples of isoprene lipids

Answer 3

Steroids, fat-soluble vitamins, dolichol-P, coenzyme Q

Question 4

What is dolichol-P?

Answer 4

Lipid of endoplasmic reticulum membrane that is involved in protein glycosylation

Question 5

What is coenzyme Q?

Answer 5

Involved in oxidative phosphorylation

Question 6

What Greek letter denotes the terminal carbon in a fatty acid?

Answer 6

Omega

Question 7

What are the two essential fatty acids that must be supplied by the diet?

Answer 7

Linoleic acid and linolenic acid

Question 8

What is the backbone of a glycerolipid?

Answer 8

Glycerol

Question 9

What is the backbone of a sphingolipid?

Answer 9

L-serine derivative

Question 10

Where do eiconisoids come from?

Answer 10

They are derivatives of polyunsaturated fatty acids

Question 11

Name 2 types of glycerolipids

Answer 11

Triacylglycerol and glycerophospholipids

Question 12

Name 2 types of sphingolipids

Answer 12

Sphingomyelins and glycolipids

Question 13

What are 2 types of glycolipids and what is the different between them?

Answer 13

Cerebrosides are made of monosaccharides, gangliosides are made of polysaccharides

Question 14

What are the structural components of a phosphoglycerol?

Answer 14

Polar head group with phosphorylated alcohol and diacylglycerol

Question 15

What are the 5 most common phosphoglycerols?

Answer 15

PC, PE, PS, PI, and CL

Question 16

PA

Answer 16

Phosphatidate
Polar head group is made of water

Question 17

PC

Answer 17

Phosphatidylcholine
Polar head group is made from choline

Question 18

PE

Answer 18

Phosphatidylethanolamine
Polar head group is made of ethanolamine

Question 19

PS

Answer 19

Phosphatidylserine
Polar head group is made from serine

Question 20

PG

Answer 20

Phosphatidylglycerol
Polar head group is glycerol

Question 21

CL

Answer 21

Cardiolipin/diphosphatidylglycerol
Made from PG

Question 22

PI

Answer 22

Phosphatidylinositol
Polar head group is made from inositol

Question 23

Where is CL found?

Answer 23

Inner mitochondrial membrane

Question 24

List the net charges of the phosphoglycerols

Answer 24

PS, -1
PC, 0
PE, 0
PI, -1
CL, -2

Question 25

What are plasmalogens?

Answer 25

Glycerophospholipids found in the CNS that has a vinyl ether linkage at C1 instead of an ester linkage

Question 26

What arethe typical polar head groups of plasmalogens?

Answer 26

Ethanolamine or choline

Question 27

List the four classes of phospholipases and specify where the cleave a phosphoglycerol

Answer 27

PLA1: cleaves ester bond at carbon 1 PLA2: cleaves ester bond at carbon 2 PLC: cleaves phosphoester bond to glycerol carbon 3 PLD: cleaves phosphoester bond between phosphate and polar head group

Question 28

What is the hydrophobic component of a sphingolipid called?

Answer 28

Ceramide

Question 29

What are the structural differences between ceramide and diacylglycerol?

Answer 29

1. The backbone of ceramide of NCC, not CCC 2. Ceramide contains one C-C bond between the backbone and one fatty acid chain

Question 30

What are the alcohol molecules attached to the polar head groups of sphingomyelins?

Answer 30

Choline or ethanolamine

Question 31

What is the net charge of a sphingomyelin?

Answer 31

0

Question 32

How is a glycolipid produced?

Answer 32

Attaching one or more sugar residues to the primary alcohol of ceramide

Question 33

What types of molecules can pass through a lipid bilayer?

Answer 33

Hydrophobic molecules and small, uncharged polar molecules

Question 34

What membrane component controls its fluidity?

Answer 34

The fatty acid content of membrane lipids

Question 35

What two phases of the bilayer are in equilibrium?

Answer 35

Lamellar liquid crystalline phase and lamellar gel phase

Question 36

When is the lamellar gel phase of the bilayer favored?

Answer 36

In conditions where the fatty acid chains can pack closely together (i.e. low temperatures)

Question 37

How can saturated fatty acid chains produce temporary fluidity?

Answer 37

Free rotation about C-C bonds produces a short-lived gauche conformer

Question 38

What structural feature of a fatty acid chains best maintains distance and fluidity in a bilayer?

Answer 38

Double bonds, ideally closer to the center of the carbon chain

Question 39

What type of fatty acid favors the gel phase?

Answer 39

Saturated fatty acids with longer carbon chains

Question 40

How does cholesterol disrupt both the fluid and gel phase of the lipid bilayer?

Answer 40

It wedges itself within the bilayer and disrupts the adoption of gauche conformers and Van der Waals interactions

Question 41

Define melting temperature (Tm)

Answer 41

Temperature required for a fatty acid to transition from the gel phase to the liquid phase

Question 42

How does carbon chain length effect Tm?

Answer 42

Tm increases because more energy is required to break more IMFs

Question 43

Effect of cis double bonds on Tm

Answer 43

Tm decreases with cis double bonds, especially when the double bond is in the center of the carbon chain

Question 44

Why are trans fats bad?

Answer 44

The presence of trans double bonds stabilizes the gel state more so than a saturated fatty acid does. This is because double bonds cannot rotate and therefore cannot adopt a gauche configuration

Question 45

Which of the fatty acids are cylindrically shaped?

Answer 45

PC, PS, PI, PG, PA, cardiolipin, SM, glycoL

Question 46

What is the shape that forms after cylindrical fatty acids aggregate in a bilayer?

Answer 46

Lamellar

Question 47

Which fatty acid is not cylindrical and what shape does it have?

Answer 47

PE, cone shaped

Question 48

What unique structure does PE frm?

Answer 48

Vesicles in the HII phase

Question 49

Summarize the importance of PE's ability to form vesicles

Answer 49

It promotes membrane fusion and fission, integrates proteins into membranes, and induces changes in protein structure