Lipids

Question 1

Are fats hydrophobic or hydrophilic?

Answer 1

Hydrophobic - water repelling

Question 2

Name the 3 main types of lipids

Answer 2

1. Triglycerides
2. Phospholipids
3. Sterols (multiple carbon ring structure)

Question 3

Triglycerides are made up of…?

Answer 3

one glycerol group + 3 x fatty acids

Question 4

Phospholipids are made up of…?

Answer 4

one glycerol + 2 x FA + phosphate + organic molecule

Question 5

Triglycerides can be saturated or unsaturated. What does this mean and what are the two types of unsaturated fats?

Answer 5

Saturated = no double bonds

Unsaturated =
Monounsaturated - 1 double bond (includes omega 9)
Polyunsaturated = >1 double bond (includes omega 3 and 6)

Question 6

Main functions of lipids?

Answer 6

Provide energy from food and store energy in body fat

Also: insulation, protection for organs and bones, hormones, structural component of cell membranes, cell signalling, conversion of vit D from sunlight

Question 7

Linolenic acid is also known as what?

Answer 7

Omega 3

Question 8

Linoleic acid is also known as what?

Answer 8

Omega 6

Question 9

What’s the basic structure of a fatty acid?

Answer 9

chain of carbon and hydrogen atoms + acid group (COOH) + methyl group (CH3)

Question 10

What is the goal of fat digestion?

Answer 10

dismantle triglycerides into small molecules that the body can absorb and use (monoglycerides, fatty acids and glyercol)

Question 11

Fat digestion in the GI tract…

Answer 11

Mouth: some hard fats begin to melt; lingual lipase secreted

Stomach: churning disperses fat; gastric lipase hydrolyses a small amount of fat only

Small intestine: bile from gall bladder emulsified fat; pancreatic lipase breaks triglycerides into monoglycerides, gycerol and fatty acids to be absorbed

Large intestine: some fat and cholesterol trapped in fibre and exits in faeces

Question 12

Percentage of total fats that should make up adult diet (recommendation)

Answer 12

20-35% of total energy intake

Question 13

Characteristics of saturated fatty acids

Answer 13

solid at room temperature
stable
straight chemical structure

Question 14

What are the 3 types of saturated fatty acids?

Answer 14

1. short-chain fatty acids (2-5 carbons long), lots of health benefits, non-essential
2. medium-chain fatty acids (6-10 carbons long)
3. long-chain fatty acids (11-40 carbons long)

Question 15

Dyslipidaemia (abnormal blood lipids) are a risk factor for what?

Answer 15

chronic diseases such as heart disease and stroke
they contribute to atherosclerosis

Question 16

Some health benefits of monounsaturated fatty acids

Answer 16

1. support memory and cognitive function
2. structural integrity of cell membranes
3. reduce blood clotting, oxidative stress, atheroma plaque formation, risk of gall stone formation

Question 17

Some functions of polyunsaturated fatty acids

Answer 17

• cell membrane integrity and fluidity
• raise HDL cholesterol

*risk of adverse affects if consumed in high amounts

Question 18

Phospholipids have X and X groups?

Answer 18

Choline and phosphate

Question 19

An omega-3 fatty acid has its first double bond…?

Answer 19

Third carbon from the methyl end

Question 20

What is the purpose of chylomicrons?

Answer 20

Transport dietary cholesterol and triglycerides via the lymphatic system to cells of the body including adipose tissue for storage and muscles for energy

Question 21

Where are chylomicrons assembled?

Answer 21

in the intestinal epithelial cells

Question 22

Which lipoprotein is the largest in size?

Answer 22

Chylomicron

Question 23

What are the precursors for synthesis of the eicosanoids?

Answer 23

Long-chain polyunsaturated fatty acids

Question 24

The oils found in walnuts, soybeans, flaxseed and wheat germ represent a good source of preformed…?

Answer 24

linolenic acid

Question 25

What type of fat is lecithin?

Answer 25

Phospholipid

Question 26

What is the hormone that signals the release of bile in fat digestion?

Answer 26

Cholecystokinin