Lipids

Question 1

What is the structure of fatty acids?

Answer 1

Long chains of hydrocarbon tail with a carboxyl group (COOH) at one end

Question 2

What are the most common carbon chain lengths for fatty acids?

Answer 2

C12 to C20

Question 3

What is the typical pKa range for fatty acids?

Answer 3

4.7-5.0

Question 4

What are the two broad types of fatty acid numbering systems ?

Answer 4

Systematic- with C1 being the carboxylic acid group
Alternative- using omega or n to denote methyl C

Question 5

What is the significance of the cis form of biological fatty acids?

Answer 5

It is the form in which biological fatty acids are found

Question 6

What is the most common saturated fatty acid?

Answer 6

Palmitic acid
Hexadecanoic Acid (16:0)

Question 7

What is the most common monounsaturated fatty acid?

Answer 7

cis-Δ9-Octadecanoic Acid (18:1(n-9))
18 carbons long, 1 double bond, omega carbon (no at the end)

Question 8

What are essential fatty acids?

Answer 8

Fatty acids that must be obtained from the diet, such as Alpha Linolenic Acid and Linoleic Acid

Question 9

What is the energy yield from complete oxidation of fatty acids?

Answer 9

~38 kJ/g

Question 10

What are triacylglycerols (TAGs)?

Answer 10

Lipids formed by glycerol and fatty acids, used for energy storage

Question 11

What is the difference between simple TAGs and mixed TAGs?

Answer 11

Simple TAGs have 3 identical fatty acid chains, while mixed TAGs have different fatty acid chains

Question 12

What are phospholipids?

Answer 12

Glycerol-based lipids with a phosphate group, making them amphiphilic

Question 13

What is a sphingolipid?

Answer 13

A membrane lipid that contains sphingosine instead of glycerol
Eg. Ceramide

Question 14

What is the role of cholesterol in membranes?

Answer 14

Membrane fluidity
It increases rigidity at high temperatures and prevents crystallization at low temperatures

Question 15

What are terpenoids synthesized from?

Answer 15

Isoprenoids

Question 16

What are lipoproteins?

Answer 16

Complexes of lipids and proteins that transport fatty acids in circulation

Question 17

What is the function of lipopolysaccharides?

Answer 17

They are composed of lipids and carbohydrates, often found in bacterial membranes

Question 18

Fill in the blank: The most common steroid in animals is ______.

Answer 18

Cholesterol

Question 19

True or False: All lipids are polar molecules.

Answer 19

False

Question 20

What are common head groups found in phosphoglycerides?

Answer 20

• Ethanolamine
• Choline

Question 21

What is the main function of glycolipids?

Answer 21

Act as recognition molecules in cell membranes

Question 22

What is stearic acid ?

Answer 22

Octadecanoic acid (18:0)
18 carbons long, no unsaturated carbons (so no double bonds)

Question 23

Unsaturated fatty acids

Answer 23

Have double bonds
So kinks in the chain

Question 24

What is essential if you are deficient in linoleic acid ?

Answer 24

Arachidonic acid

Question 25

What are the functions of TAGs ?

Answer 25

1. Insulation 2. Protection 3. Store energy

Question 26

What is sphingomyelin ?

Answer 26

A sphingolipid Structural component on myelin sheath Alters fluidity 25% of all lipid in humans

Question 27

What are glycolipids ?

Answer 27

They contain a carbohydrate Act as recognition molecules

Question 28

What does amphipathic mean ?

Answer 28

A molecule has hydrophilic and hydrophobic parts

Question 29

What are terpenoids a precursor for ?

Answer 29

1. Vitamin A 2. Vitamin K 3. Ubiquinone