Lecture 9

Question 1

Define a lipid

Answer 1

A class of organic compounds that are Fatty Acids or their derivatives that are insoluble in H2O but soluble in organic solvents

Question 2

What are the functions of lipids?

Answer 2

1. Main storage form of energy
2. Component of cell membranes
3. Provides insulation
4. Cushions to protect internal organs
5. Basis of many hormones e.g. test, estrogen, adrenaline
6. Basis of eicosanoids involved in reproduction immunity and cell signalling

Question 3

What are the types of lipids?

Answer 3

1. Triglycerides
2. Fatty Acids
3. Phospholipids
4. Sterols
5. Sphingolipids - important in the brain
6. Fat soluble vitamins

Question 4

What are examples of sterols?

Answer 4

Sex hormones, cholesterol, bile acids

Question 5

What are sphingolipids important in?

Answer 5

The brain

Question 6

What % are of dietary acids are triglycerides?

Answer 6

More than 90%

Question 7

Which lipid is the main lipid in adipose tissue?

Answer 7

Triglycerides

Question 8

Which lipid is the main energy store?

Answer 8

Triglycerides

Question 9

What is the structure of Triglycerides?

Answer 9

glycerol + 3x fatty acids = triglyceride

Question 10

TRUE OR FALSE

A triglycerides will have a mixture of fatty acids

Answer 10

TRUE

Question 11

What kind of bond is between the glycerol and the Fatty Acid?

Answer 11

Ester

Question 12

Describe a fatty acid

Answer 12

Chain of carbon molecules with a methyl group at one end and a carboxyl group at the other end

Question 13

What is another way to describe the methyl end?

Answer 13

Omega

Question 14

In what range can humans not add a double bond in a fatty acid?

Answer 14

Between C1 and C6

Question 15

What are factors affecting Fatty Acids?

Answer 15

1. Length of the chain
2. Double bonds
3. Position of first double bond from methyl end

Question 16

What is the effect of changing the length of a FA chain?

Answer 16

The properties change as the length changes

Question 17

What length are most FA in the diet?

Answer 17

Between C10-C22

Question 18

What is the effect of double bonds on FA?

Answer 18

Affects the melting point

Question 19

What is an essential FA?

Answer 19

A FA that must be obtained from the diet

Question 20

What are 2 examples of essential FA and where is their double bond placement?

Answer 20

1. Linoleic acid = omega 6 fat

2. Linolenic acid = omega 3 fat

Question 21

Describe a Saturated FA

• melting point
• example

Answer 21

• Saturated with hydrogen
• No double bonds
• High melting points, solid at room temperature
• Stearic Acid (C18:0)

Question 22

Describe a Monounsaturated FA

-example

Answer 22

• Has one double bond
• Oleic acid (C18:1n-9)
• Melting point is 16 degrees

Question 23

Describe the effect of trans/cis bonds

Answer 23

-Change will effect the melting point

Question 24

Like what other FA does a trans bond act like?

Answer 24

Saturated FA

Question 25

Describe a Polyunsaturated FA

Answer 25

- More than 1x double bond - Low melting point - Alpha-linolenic acid (C18: 3n-3)

Question 26

What % of total energy should essential FA make up?

Answer 26

1-3%

Question 27

What are symptoms of essential FA deficiency?

Answer 27

- Growth retardation - Reproductive failure - Skin lesions - Kidney and liver disorders - Neurological and visual problems

Question 28

What % of dietary lipid do phospholipids account for?

Answer 28

5-10%

Question 29

TRUE OR FALSE FA is one of the few compounds that dietary intake can have an influence on what happens inside the body

Answer 29

FALSE FA is the ONLY one that has this effect

Question 30

What is the structure of sterols?

Answer 30

Multiple ring structure

Question 31

What foods are sterols found in?

Answer 31

In plant and animal foods

Question 32

What are sterols the starting material for?

Answer 32

1. Bile acids 2. Sex hormones 3. Adrenal hormones 4. Vit D

Question 33

Where are sphingolipids found?

Answer 33

In brain tissue and nervous tissue

Question 34

What is the recommended intake of fat?

Answer 34

No specific intake of grams of fat

Question 35

What is the AMDR of fat?

Answer 35

20-35% of total energy

Question 36

Where is NZ in the range of AMDR?

Answer 36

We are in the range, 34%

Question 37

Where are NZ's main fat sources in food?

Answer 37

1. Butter/margarine 2. Potatoes, kumara, taro (not the food themselves but how we prepare them) - Mainly ANIMAL products