Lipids and Fatty Acids

Question 1

What is the only thing lipids are soluble in?

Answer 1

Only soluble in non-polar solvents

Question 2

Are fatty acids, hydrophobic or hydrophilic?

2

Answer 2

They are amphiphilic

But the hydrocarbon chain generally makes them act hydrophobic

Question 3

What are the three main functions of lipids in the body?

Answer 3

Energy storage

Cellular signalling

Cellular structural components

Question 4

Describe the structure of a fatty acid?

Answer 4

A carboxylic acid (COOH) joined to a long hydro-carbon chain

Question 5

What is formed when fatty acids undergo saponification?

Answer 5

Soap and glycerol

Question 6

What are the two classifications of fatty acids?

Answer 6

Saturated fats

Unsaturated fats

Question 7

What is a mono-unsaturated fatty acid?

Answer 7

One carbon-carbon double bond is present

Question 8

What is a poly-unsaturated fatty acid?

Answer 8

Two or more carbon-carbon double bonds are present

Question 9

How can unsaturated fats be subcategorised?

Answer 9

By the type of double bond present (cis or trans)

Question 10

Write a note on trans fatty acids.

4

Answer 10

Increase amount of LDL

Reduce amount of HDL

Naturally occurring, higher levels in processed foods

Found in butter, milk, ground beef etc

Question 11

Write a note on cis fatty acids.

5

Answer 11

Increase amount of HDL

Naturally occurring

Hydrogenated during food processing to form a saturated fat

Isomerisation during processing to form a trans fat

Found in olive oil, vegetable oil, avocado etc

Question 12

How are fatty acids named symbolically?

Answer 12

x:y ^(Da, b, c)

x = number of Cs in chain
y = number of double bonds
a, b, c are the position of double bonds counting from C1 at the carboxyl end

Question 13

What is the x in the symbolic naming of fatty acids?

Answer 13

The number of Cs in the chain

Question 14

What is the y in the symbolic naming of fatty acids?

Answer 14

The number of double bonds in the chain

Question 15

What is the a, b, c in the symbolic naming of fatty acids?

Answer 15

The position of double bonds counting from C1 at the carboxyl end

Question 16

What are the four most common omega acids?

Answer 16

Omega-3

Omega-6

Omega-7

Omega-9

Question 17

How are omega acids named?

3

Answer 17

Omega means its unsaturated

The number tells you where the double bond is

Count back from the last carbon on the hydrocarbon chain

Question 18

What are triacylglycerides?

2

Answer 18

Molecules that contain one glycerol group and three fatty acid chains joined by an ester bond

Very hydrophobic

Question 19

Where does the ester bond of TAGs form?

Answer 19

They form at the interface between an OH group on the glycerol and the carboxylic acid of the fatty acid

Question 20

What is a glycerol?

Answer 20

A 3 carbon sugar alcohol

Question 21

Give three characteristics of glycerol.

Answer 21

Odourless

Colourless

Slight sweet taste

Question 22

Give a use of glycerol.

Answer 22

Used as a bulking agent in many products

Question 23

How many fatty acids can a glycerol bind?

Answer 23

Three

Question 24

What physical change takes place when an unsaturated fatty acid is hydrogenated?

Answer 24

An oil becomes a solid

Question 25

What are waxes? | 2

Answer 25

Chemically heterogenous group of compounds Formed by an Ester which combines a long chain fatty acid and a long chain alcohol

Question 26

Write a note on waxes. | 4

Answer 26

Found in both animals and plants Prevent water loss and protection from pests in plants Generate a water proof coating in animals Used in candles, car waxes, cosmetics etc

Question 27

What are membrane lipids/phosphoglycerides? | 2

Answer 27

Highly variable between tissues and cells General structure consists of a glycerol 3-phosphate molecule joined with 2 fatty acids

Question 28

What 2 fatty acids join the glycerol 3-phosphate molecule?

Answer 28

A saturated C16 or a saturated C18 fatty acid at C1 An unsaturated C18-20 fatty acid at C2

Question 29

How is a phosphoglyceride named?

Answer 29

Based on what is attached at the head group substituent of the phosphate group Phosphatidyl-X

Question 30

What are the two most common phosphoglycerides?

Answer 30

Ethanolamine containing Choline containing

Question 31

Write a note on phosphatidylethanolamine. | 3

Answer 31

Found on the inner leaflet of the plasma membrane Important to heart health Plays a part in blood clotting

Question 32

Write a note on phosphatidylcholine. | 4

Answer 32

Found on the outer leaflet of the plasma membrane Found in nearly every cell of the body Important in the central nervous system Commercial use as an emulsifying agent

Question 33

What are plasmalogens?

Answer 33

A specific class of phosphoglyceride, which contain an ether linked alkenyl chain at the C1 position

Question 34

Give an example of a plasmalogen.

Answer 34

Platelet Activating Factor | PAF

Question 35

What does PAF do? | 2

Answer 35

Signals for the aggregation of platelets at the site of injury Has a role in inflammation and in allergic reactions

Question 36

What are sphingolipids? | 4

Answer 36

Based on a 3 carbon backbone. similar to glycerol Sphingosine added at the C3 position Fatty acid bound at C2 position (16,18,22 or 24 carbons - sat or unsat) Ceramide or ceramide derivative at the C1

Question 37

What is sphingosine?

Answer 37

A long chain amino alcohol

Question 38

What are glycosphingolipids?

Answer 38

They define your blood type

Question 39

What are the five different types of fatty acids?

Answer 39

Triacylglycerols Waxes Glycerophopholipids Sphingolipids Glycosphingolipids