Chapter 9: Lipids and Membranes

Question 1

The 8 major categories of lipids include:

Answer 1

Fatty acids
Glycerolipids
Glycerophospholipids
Sphingolipids
Sterol lipids
Prenol lipids
Saccharolipids
Polyketides

Question 2

The universal form of stored energy in nature is?

Answer 2

Fat and oils in the form of fatty acids

Question 3

What does the oxidation of fatty acids yield?

Answer 3

CO2 and H2O

*like combustion of hydrocarbon fuels

Question 4

Fatty acid structure:

Answer 4

a.) carboxylic end

b.) hydrocarbon chain of 4-36 carbons

c.) polyunsaturated

Question 5

What lipids do humans require in our diet?

Answer 5

omega-3 PUFA (ALA) to synthesize EPA and DHA which is important for cell function

Question 6

Are saturated FA’s soluble?

Answer 6

NO, PUFA’s are slightly more soluble in water

Question 7

What is melting point of fatty acids determined by?

Answer 7

Length of FA and degree of saturation

Saturated= higher MP

Question 8

Why do saturated FA have higher MP’s?

Answer 8

Due to the tight packing of saturated FAs (unsaturated fats have a loose association)

Question 9

Discuss fatty acid transport.

Answer 9

FA’s are bound to serum albumin and transported through the circulatory system.

Question 10

Why are some FA’s harder to transport?

Answer 10

Hard to transport if they are in the ESTER form called triacylglycerols. They are less soluble and diffucult to move.

Question 11

Triacylglycerols do what?

Answer 11

Simplest lipid constructed from FA’s. TAG is the preferred energy storage and they provide insulation.

Question 12

Human adipocytes are?

Answer 12

a.) Huge fat droplets that fill the cells.
b.) Stripped down cells with very little functionality.
c.) Hydrolyze TAG with stored enzyme lipase

Question 13

Why and what are trans fats?

Answer 13

To improve the shelf life of foods, commercial vegetable oils were
subjected to partial hydrogenation which converts cis double bonds to
trans double bonds.

Trans fats increase TAG, LDL, and cholesterol levels in blood causes an inflammatory response

LDL- low density lipoprotein

Question 14

Strucure of wax?

Answer 14

a.) long chain saturated and unsaturated fatty acids (C14-C36)
b.) head group that consists of long alcohol groups (C16-C30)

MP is 60-100 celsius

Question 15

How are waxes used in real life?

Answer 15

Marine organisms: as a fuel source, structural features of habitats, waterproof features on skin

Cosmetics and Pharmaceuticals: drugs, lotions, ointments, and polishes

Question 16

Membrane lipids have a polar and nonpolar end, they are _____

Answer 16

amphipathic

Question 17

Storage lipids (neutral)

Answer 17

glycerol + 3 fatty acid chains

Question 18

Membrane lipids - phospholipids - glycerophospholipids

Answer 18

Glycerol + 2 fatty acid chains + (phosphoanhydride + alcohol)

Question 19

Membrane lipids - phospholipids - sphingolipids

Answer 19

Sphingosine (amine) + 1 fatty acid chain + (phosphoanhydride + choline)

Question 20

Membrane lipid - glycolipid - sphingolipid

Answer 20

Sphingosine (amine) + 1 fatty acid chain + mono or oligosaccharide

Question 21

Membrane lipid - glycolipid - galactolipids

Answer 21

Glycerol + 2 fatty acid chains + (mono or oligosaccharide and SO4)

Question 22

______ are often part of the cell membrane and act as a physical
barrier for polar molecules and ions

Answer 22

Structural lipids

Question 23

Archael tetrether lipids

Answer 23

2 very long acyl chains are etherlinked to glycerol at both ends

acyl: carbonyl group + R group + functional group

Question 24

Sterols

Answer 24

composed of 4 rigid fused hydrocarbon rings

Question 25

What are the 5 general types of membrane lipids?

Answer 25

1.) Glycerophosphilipids
2.) Galactolipids
3.) Archael tetraether lipids
4.) Sphingolipids
5.) Sterols

Question 26

Why is it so difficult to study the membrane?

Answer 26

Most structural parts are inside the membrane, it’s very hard to see and hydrophobic nature makes it hard to isolate them

Question 27

Glycerophospholipids that have ether-linked alkenyl chain instead of esterlinked fatty acid

Answer 27

Plasmalogens

Question 28

Galactolipids predominate where?

Answer 28

Largely stored in the thylakoid membrane of chloroplasts, because phosphate is a limiting reagent in soils

Question 29

Where is sphingomyelin found?
- a form of sphingolipid

Answer 29

Myelin, a membranous sheath surrounding and insulating axons of neurons

Question 30

Where are glycosphingolipids are found?

Answer 30

In outer leaflet of plasma membranes, have a sugar on their head group

Question 31

Where are cerebrosides found?

Answer 31

Neural tissue

Question 32

Where are globosides found?

Answer 32

Neural tissue but they have more than one sugar gorup