Lipids

Question 1

What are the 3 main classifications of lipids?

Answer 1

1.) Triglycerides
a. Fats and Oils
b. 95% of lipids in our diets

2.) Phospholipids
a. Lecithin
5% of lipids in our diet
3.) Sterols
a. Cholesterol

Question 2

What is the structure of a triglyceride?

Answer 2

Glycerol + 3 fatty acids= Triglyceride

Question 2

What are the functions of fat in the body? What are the functions of fat in foods?

Answer 2

Functions of fat in the body:
- Concentrated form of calories
- Serves as an energy reserve.
- Major component of cell membranes
- Insulate the body.
- Provide padding & protection to vital organs.
- Nourishes skin and hair.

Functions of fat in foods
- Provides calories.
- Provide satiety!
- Feeling of fullness or satisfaction after meals
- Carry fat-soluble vitamins and essential fatty acids!
- Contribute aroma and flavor!

Question 3

What are fatty acids? What is the difference between a saturated and unsaturated fatty acid?

Answer 3

• Chains of carbon and hydrogen
• Contain an acid group (COOH)
• Chain length = number of carbon atoms hooked together
• Short chain FA = soluble in water
• Long chain FA = insoluble in water
• Saturation = number of hydrogen atoms in a fatty acid
  saturated is solid at room temperature and unsaturated is liquid at room temperature

1.) Saturated Fatty Acid
a. C = carbon
b. H = Hydrogen
c. Fully loaded with hydrogen atoms
d. indicates a single bond.
e. = indicates a double bond

2.) Unsaturated Fatty Acids
a. “point of unsaturation.”
b. Monounsaturated fatty acid (MUFA) =
1 point of unsaturation
c. Polyunsaturated fatty acid (PUFA) =
2 or more points of unsaturation

Question 4

What role does the degree of saturation/unsaturation play on foods? What do food manufacturers do to alter this?

Answer 4

Amount of unsaturated FA in a fat affects the temperature at which fat melts.
↑ unsaturation = more liquid
↑ saturation = more solid (Ex. Oreos)

Points of unsaturation are weak – can be attacked by oxygen and turn rancid. (Ex. Leaving an apple out causing oxygen to get in and the apple will become brown.
Can treat by hydrogenation.

Add hydrogen to points of unsaturation.
Lose health benefits that go with unsaturation.
Can create Trans fats!

Answer: It affects the temperature at which it melts
- can treat with hydrogenation and create trans-fat (lose health benefits)

Question 5

Digestion: where it takes place, enzymes discussed in class. (Figure 5-8)

Answer 5

1. Mouth – some hard fats begin to melt (No digestion in the mouth)
2. Stomach – churning action mixes fat with stomach acid; lipase breaks apart a small amount of fat.
3. Liver makes bile, stored in gallbladder, released into small intestine – emulsifies fat with digestive juices
4. Pancreas – produces pancreatic lipase which enters the small intestine

Question 6

Absorption: Describe the absorption process, including how fats are absorbed and what happens to them once they enter the cells of the small intestine.

Answer 6

• Products of fat digestion: fatty acids, glycerol, and monoglycerides
• Fats are absorbed through the small intestine
• Fatty acids reconnect with glycerol and/or monoglycerides (Meaning it has one fatty acid attached) to make new TG (Tryglycerids) in intestinal cells
• New TG and other lipids combine with proteins to form chylomicrons
• Chylomicrons are a form of lipoprotein

Question 7

What is LPL (lipoprotein lipase)? What does it do?

Answer 7

• Increased fat intake activates enzyme (LPL) that promotes fat storage
• When they say “kids will grow out of it” does not mean that fat cells are not there anymore, because they are and later on in the future, they can develop diabetes