Lecture 7 - Lipids Flashcards

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1
Q

What are the 3 main types of lipids

A

Triglycerides
Phospholipids
Sterols

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2
Q

What lipid group makes up 90-95% of the lipids we consume?

A

Triglycerides

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3
Q

What are the 4 important structural parts that make up a triglyceride?

A
  1. Glycerol backbone
  2. 3 different fatty acid chains
  3. An acid group (COOH)
  4. Methyl group (CH3)
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4
Q

What are the 2 forms fatty acids can be in?

A

Saturated

Unsaturated

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5
Q

Why are the 3 fatty acid chains different?

A

They are composed of the materials that are present at the time. Whatever fatty acids are available will end up attached to the backbone

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6
Q

Are fatty acids organic?

A

Yes because it has C

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7
Q

How long can fatty acid chains be?

A

Length is dependent on how many C’s its composed of

Long (14-24)
Medium (6-12)
Short (Less than 6)

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8
Q

How long are most fatty acids that we consume?

A

Log chain

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9
Q

Why don’t we eat short chain fatty acids?

A

We can make them in our gut and then we can absorb them

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10
Q

What determines fatty acid digestion?

A

Chain length

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11
Q

What is a saturated fatty acid?

A

A chain fatty acid in which all C’s are filled with H’s

No double bonds

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12
Q

What is an unsaturated fatty acid?

A

A chain fatty acid which contains double bonds instead of H’s

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13
Q

What are the 2 types of unsaturated fatty acids?

A

Monosaturated
-1 double bond
Polysaturated
-2 or more double bonds

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14
Q

What do double bonds do to the fatty acid structure

A

Double bonds change the shape of the fatty acid, making it less stackable

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15
Q

What is a double bond technically called?

A

A kink

-changes the direction of the fatty acid

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16
Q

What will happen to lipids when it is completely saturated?

A

They are more likely to be solid at room temp because there are no kinks in the conformation, making the triglycerides more stackable. Therefore there is less room for the lipids to move

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17
Q

What will happen to lipids when it is unsaturated?

A

The kink from the double bond will change the direction of the rest of the chain, making more room for the 3 chains tome around. Lipid is more likely to be liquid at room temp.

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18
Q

How do you identify the location of a double bond?

A

The C in the methyl group is Omega 1 C, then the next C would be 2 and so on.

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19
Q

Can you switch an Omega 3 fatty acid to an Omega 6 fatty acid?

A

No, they are completely different families.

You can add H’s and double bonds to them, but they can not change families

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20
Q

What are the 2 essential fatty acids?

A

Linoleic acid

Alpha Linolenic acid

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21
Q

Which family is linoleic acid from, and what is its chemical name?

A

Omega 6

18: 2n-6
- shortest 6 in their family

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22
Q

Which family is alpha linolenic acid from, and what is its chemical name?

A

Omega 3

18: 3n-3
- shortest 3 in their family

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23
Q

What happens when we eat the essential fatty acids?

A

Linoleic acid is converted into AA

Alpha Linolenic acid is converted into EPA and DHA

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24
Q

What is the function of AA EPA and DHA?

A

All converted molecules are involved in cell signalling with opposing effects (6 vs. 3)

Act as hormones as cell signalling agents in a localized area

All have different effects so we need to balance these

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25
Q

How are triglycerides formed?

A

Condensation reactions

Glycerol+3Fatty Acids= Triglyceride + H2O

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26
Q

What are the 3 categories that oils fall into?

A

Saturated Fat

Monosaturated

Polysaturated

  • characterized by how much of each group it has.
  • all oils are a mix of the 3
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27
Q

What are examples of oils rich in saturated fat?

A

Animal fats (butter, lard)

Tropical oils (coconut, palm)

28
Q

What are examples of oils rich in monounsaturated fats?

A

Olive and canola oil

29
Q

What are examples of oil rich in polysaturated omega 3 fats?

A

Flaxseed oil

30
Q

What are examples of oil rich in polyunsaturated omega 6 fats?

A

Sunflower and corn oil

31
Q

What is hydrogenation?

A

When you add H’s to unsaturated fatty acids causing the double bonds to break

32
Q

What are the properties of hydrogenation

A

Makes liquid fat more solid at room temp

-does this by switching H configuration from cis to trans

33
Q

Why was hydrogenation created?

A

Invented for shelf stability

34
Q

What is a phospholipid?

A

Same as a triglyceride but instead of 3 fatty acids chains, on has a phosphate head

35
Q

Where do we get our source of phospholipids?

A

Lecithin in eggs and soy

36
Q

What is the function of phospholipids?

A

They act as emulsifiers, making something partially water and fat soluble

37
Q

What is a characteristic about sterols?

A

Their ring structure

38
Q

What is the most common sterol and how to we get it?

A

Cholesterol

We don’t need to get it from anywhere because we make it in the liver

39
Q

In what food is cholesterol most common?

A

Only found in Animal fats

-plants have sterols

40
Q

Why do we need cholesterol?

A

Need it to make other things our body needs
-bile acids, hormones and vitamin D

Structural components of the cell

Plaque formation

41
Q

Why are plant sterols good?

A

The more plant sterols we eat the less cholesterol we are consuming and the less cholesterol we have in our body
-has the opposite effect of cholesterol

42
Q

What is the downside to plant sterols?

A

We don’t really absorb them that well

43
Q

What is the process of lipid digestion?

A
  1. Mouth releases lingual lipase but digestion does not start here
  2. In the stomach, gastric lipase is present but digestion hasn’t really started yet
  3. In the small intestines, CCK is released which tells the pancreas to release enzymes, and tells the gallbladder to release bile
44
Q

Why is bile important in lipid digestion?

A

bile acts as an emulsifier, which caused the dat to be broken down into tiny particles so it can be brought down into the water liquid in a micelle

45
Q

What is a micelle?

A

emulsified fat droplet

-cuts off 2 fatty acid chains from the triglyceride to leave a monoglyceride

46
Q

What are the 2 fates of bile after it has been used?

A

Reabsorbed and recycled

Excreted

47
Q

Why is bile excretion good?

A

Since bile is made of cholesterol, if we excrete more then we are reducing the about the gets reabsorbed which intern increased blood cholesterol

48
Q

When micelle crosses the cells in the small intestine wall, what will it have with it?

A

Tiny fat particles

All other fat soluble things such as vitamins

49
Q

What happens after the micelle passes through the small intestine wall cells?

A

Triglycerides are put back together in an organized form called chylomicrons

50
Q

What is a chylomicron?

A

Type of lipoprotein that transports fat throughout the body, composed of long chain triglycerides
-takes diet fat directly into the body

51
Q

What is the fate of small and medium chain fatty acids after they have crossed the small intestine cell walls?

A

They go right into the blood straight to the liver

52
Q

Where does the chylomicron go?

A

Into the lymphatic system, but enters the blood still as a chylomicron

53
Q

What are the 3 types of lipoproteins and their characteristics?

A
  1. Chylomicron
    - composed of a lot of dietary fat (light) and therefore not very dense
  2. LDL
    - carries cholesterol to cells in the body that need it. Mainly composed of cholesterol
  3. HDL
    - takes cholesterol out of the body, gets rid of it or uses it. Mainly composed of protein which is more dense
54
Q

Why is LDL typically considered bad?

A

When there is too much LDL (mostly made of cholesterol) it will continue to float in the blood.
-builds up over time creating plaque and blockages

55
Q

Why are lipids important

A

Need the triglycerides itself

Important because of the essential fatty acids

Protection

56
Q

What are the roles of triglycerides?

A

Provide energy

Unlimited storage

Adipose tissue

57
Q

Why is adipose tissue important?

A

Secretes a hormone called Adipokins which regulates the energy balance in the body
-either tells it to store or to break down the triglycerides into fatty acids for energy in the cell and glycerol for blood glucose

58
Q

How are triglycerides stored?

A

via Hydrolysis from Chylomicrons and VLDL by lipoprotein lipase

59
Q

What is produced when fat is being used as an energy source?

A

Ketone bodies

usually when the body is fasting

60
Q

What is the major health effect of lipids?

A

Heart disease

61
Q

Why is heart disease linked to lipids?

A

Fat in LDL is easily oxidized, cells think they re being attacked and build a protective layer that the LDL is absorbed into. As the layers build up, this forms plaque accumulation in blood vessels
-restricted blood flow leads to heart attacks

62
Q

What is the risk from eating too much saturated and trans fats?

A

Increase heart disease risk

When we eat more of these fats, our body thinks we need more cholesterol and produces more even if the food we are consuming doesn’t have any cholesterol at all

63
Q

What does saturated fat do to HDL?

A

Nothing really

64
Q

What does trans fat do to HDL?

A

Makes HDL decrease

65
Q

What is the DRI for fats?

A

20-35% of daily energy intake

66
Q

What is the Daily recommendation for fats?

A

30% of total energy intake should come from fats

10% of total energy intakes should come from saturated fats

As little trans fats as possible

67
Q

What is the mediterranean diet?

A

Diet of monounsaturated fats, lots of fish, veggies, and little red meats

Found to reduce the risk of chronic diseases