Fats - EoNS

Question 1

What are the main functions of fats?

Answer 1

●Energy store
●Hormones e.g. sex hormones
●Membranes – phospholipids
●Carrier for the Fat soluble vitamins (A, D, E, K)
●Taste & Texture of Food
●Satiety – feeling of fullness/satisfaction after a meal

Question 2

Name two lipids

Answer 2

Fats and oils

Question 3

What makes up most of the fats in the body?

Answer 3

Triglycerides AKA Triacylglycerols

Question 4

What is the structure of a triglyceride?

Answer 4

Glycerol with three fatty acids

Question 5

Which two groups are found on fats?

Answer 5

Methyl group - (CH3)
Acid group -COOH

They are found at opposite ends of the long carbon and hydrogen chain.

Question 6

How many double bonds do saturated, monounsaturated and polyunsaturated fatty acids have?

Answer 6

●Saturated fatty acids - No double bonds
●Monounsaturated fatty acids - 1 double bond
●Polyunsaturated fatty acids - 2 or more double bonds

Question 7

If a fat is unsaturated then there are two possible positions for the H atoms next to the double bond. Where would H atoms on a cis and trans be?

Answer 7

●cis – H on the same side of double bond
●trans – H on opposite side to double bond

Question 8

What are the properties of trans and cis fatty acids?

Answer 8

Trans fatty acids are packed tightly together which makes them harder to break apart and they have a higher melting point

Cis fatty acids are packed loosely together, which makes them easier to break apart and they have a low melting point

Question 9

What are trans fats also known as?

Answer 9

Hydrogenated fats

Question 10

Are trans fats saturated or unsaturated

Answer 10

Unsaturated but with similar properties to saturated

Question 11

Do saturated fats have a high or low melting point?

Answer 11

High

Question 12

Where do you find saturated fats?

Answer 12

Predominantly animal fats e.g.
- Butter, lard, cheese, meat
- Palm & coconut oils

Question 13

Do PUFA AND MUFA have a high or low melting point.

Answer 13

Low melting point – liquid at room temp

Question 14

What does the following represent? C18:2 n-3

Answer 14

18C
2 double bonds
1st double bond occurring on 3rd C

Question 15

What are essential fatty acids?

Answer 15

Some fatty acids cannot be synthesised by the body so they are essential in the diet

Question 16

What are the two essential fatty acids? I

Answer 16

Linoleic acid (18:2, n-6)

α-linolenic acid (18:3, n-3)

Question 17

What can happen if the levels of n-6 is too high

Answer 17

If levels of n-6 is high in the diet it can limit synthesis of n-3 type of acids.
The ratio of n-6:n-3 should be 6:1

Question 18

How are lipids digested and absorbed?

Answer 18

1. Lipases breaks down triglycerides into glycerol and fatty acids
2. Some of these fatty acids are very small, so they’re able to be absorbed by a simple diffusion into epithelial cells of the villi, and then they pass into blood capillaries.
3. Bile salts emulsify the larger lipids, this forms many micelles.
4. From micelles these lipids diffuse into epithelial cells of the line where they are packaged into chylomicrons.
5. Chylomicrons leave the cell via exocytosis and then enters the lymphatic fluid within the lacteal.
6. The lymphatic fluid carrying chylomicrons from the small intestine passes into the thoracic duct, then empties into the left subclavian vein.

Question 19

What are chylomicrons?

Answer 19

Large spherical triglyceride surrounded by a phospholipid and protein coat.

Question 20

How do lipids travel in the blood?

Answer 20

●Chylomicrons release triglycerides to cells
●Chylomicron remnants are recycled in liver
●Lipoproteins are also used to carry lipids in the blood

Question 21

What is cholesterol and where is found

Answer 21

1. Essential for cell membranes, hormones e.g. sex hormones, steroids & formation of bile acids
2. Can be deposited in blood vessel walls in atherosclerosis
3. Cholesterol can either be:
   Endogenous – from synthesis within body in the liver
   Exogenous – from food intake
4. Dietary cholesterol from animal sources e.g. eggs, prawns, dairy & offal meats

Question 22

What roles to LDL’s and HDL’s play?

Answer 22

LDL: Cholesterol to the tissue (Bad)

HDL: Removes surplus cholesterol & other lipoproteins from cells to liver (good)

Question 23

Give examples of saturated fat

Answer 23

Milk & milk product
Meat & meat products
Cereal products
Fat spreads
Chips/savoury snacks
Eggs & egg dishes

Question 24

How do you reduce saturated fat in the diet?

Answer 24

●Low fat dairy products
●Low fat meats, e.g. chicken
●Remove visible fat
●Replace Butter with low fat spread (high MUFA/PUFA)
●Grill/bake
●Olive/rapeseed oil, not lard