Lipids

Question 1

What are lipids?

Answer 1

Heterogeneous group of compounds

Can be extracted from tissue via nonpolar solvents

Question 2

What is the importance of lipids?

Answer 2

15% of the human body

Source of energy

Component of membranes, vitamins, hormones, and other regulatory molecules

Important in atherosclerosis and obesity

Question 3

How much free fatty acid exists in the body?

Answer 3

Practically none

A little is attached to albumin

Question 4

What is a fatty acid?

Answer 4

Hydrocarbon chains of various lengths and degrees of unsaturation with carboxylic acid groups

Question 5

How do you name saturated fatty acids?

Answer 5

Name parent hydrocarbon using number of carbons, then substitute “oic” at the end

Question 6

How do you name mono- and polyunsaturated fats?

Answer 6

Mono = ending is -enoic

Two double bonds = dienoic

Three = trienoic

Question 7

How are fatty acids named via the omega nomenclature?

Answer 7

Number of carbons: (Double bonds)n - (where the double bonds start)

E.g. Linoleic acid

18:2n-6

Question 8

What are the classifications for short-, medium-, and long-chain fatty acids?

Answer 8

Short <6 carbons

Medium = 6-12

Long = 13-21

Question 9

What are very long chain fatty acids?

Answer 9

22 or more carbons

but fatty acids that are more than 22 carbons long exist in a very small percentage in the body

Question 10

How does chain length influence membrane fluidity?

Answer 10

Shorter chain length = More fluid

Question 11

How does saturation influence membrane fluidity?

Answer 11

Less saturation = increases fluidity

Question 12

What type of lipids are storage lipids?

Answer 12

Triacylglycerols

Question 13

What is the function of triacylglycerides?

Answer 13

Provide stored energy and insulation, cushioning

Made of three fatty acid chains bound to a glycerol molecule

Question 14

Where is the unsaturated fatty acid located on the tryglyceride molecule if there is one?

Answer 14

The second carbon

Question 15

What are three advantages to using triglycerides as fuel?

Answer 15

Carbon atoms are more reduced

TG are unhydrated, less weight

Can also be used as insulation

Question 16

What are three common types of membrane lipids?

Answer 16

Phospholipids

Glycolipids

Cholesterol

Question 17

How are lipid bilayers formed?

Answer 17

Energetically favorable to remove hydrophobic fatty acids from water, so at a critical concentration, lipids spontaneously form micelles, bilayers, or liposomes.

Phospholipids prefer bilayers

Question 18

What are four characteristics of membranes?

Answer 18

Non-covalent

asymmetric

fluid

electrically polarized

Question 19

What are the four components of phospholipids?

Answer 19

Fatty Acids

Platform to attach the fatty acid

A Phosphate

An Alcohol

Question 20

What is phosphatidate?

Answer 20

Simplest phospholipid

Made of 2 fatty acid hydrocarbon chains, glycerol and phosphoric acid

Question 21

What are five common alcohol moieties?

Answer 21

Serine

Ethanolamine

Choline

Glycerol

Inositol

Question 22

What are lysophospholipids?

Answer 22

Phospholipids with only one acyl group attached.

Could be either acyl group

Question 23

What are plasmalogens?

Answer 23

Potent signaling lipids that are structurally similat to phosphotidylcholine or -ethanolamine

Contains an ether-linked alkene

Question 24

What are sphingolipids?

Answer 24

Phospholipid that contains sphingosine as a backbone instead of glycerol

Includes sphingomyelins and glycosphingolipids

Question 25

How do you differentiate sphingomyelin from other phospholipids?

Answer 25

The presence of an amide linkage

Question 26

What are glycolipids?

Answer 26

Sugar containing lipids

NOT phospholipids

Derived from sphingosine

Question 27

What is cholesterol?

Answer 27

Lipid based on a steroid nucleus

Makes membranes less fluid