Lecture 7 - Lipids Flashcards
What are the 3 main types of lipids
Triglycerides
Phospholipids
Sterols
What lipid group makes up 90-95% of the lipids we consume?
Triglycerides
What are the 4 important structural parts that make up a triglyceride?
- Glycerol backbone
- 3 different fatty acid chains
- An acid group (COOH)
- Methyl group (CH3)
What are the 2 forms fatty acids can be in?
Saturated
Unsaturated
Why are the 3 fatty acid chains different?
They are composed of the materials that are present at the time. Whatever fatty acids are available will end up attached to the backbone
Are fatty acids organic?
Yes because it has C
How long can fatty acid chains be?
Length is dependent on how many C’s its composed of
Long (14-24)
Medium (6-12)
Short (Less than 6)
How long are most fatty acids that we consume?
Log chain
Why don’t we eat short chain fatty acids?
We can make them in our gut and then we can absorb them
What determines fatty acid digestion?
Chain length
What is a saturated fatty acid?
A chain fatty acid in which all C’s are filled with H’s
No double bonds
What is an unsaturated fatty acid?
A chain fatty acid which contains double bonds instead of H’s
What are the 2 types of unsaturated fatty acids?
Monosaturated
-1 double bond
Polysaturated
-2 or more double bonds
What do double bonds do to the fatty acid structure
Double bonds change the shape of the fatty acid, making it less stackable
What is a double bond technically called?
A kink
-changes the direction of the fatty acid
What will happen to lipids when it is completely saturated?
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
What will happen to lipids when it is unsaturated?
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.
How do you identify the location of a double bond?
The C in the methyl group is Omega 1 C, then the next C would be 2 and so on.
Can you switch an Omega 3 fatty acid to an Omega 6 fatty acid?
No, they are completely different families.
You can add H’s and double bonds to them, but they can not change families
What are the 2 essential fatty acids?
Linoleic acid
Alpha Linolenic acid
Which family is linoleic acid from, and what is its chemical name?
Omega 6
18: 2n-6
- shortest 6 in their family
Which family is alpha linolenic acid from, and what is its chemical name?
Omega 3
18: 3n-3
- shortest 3 in their family
What happens when we eat the essential fatty acids?
Linoleic acid is converted into AA
Alpha Linolenic acid is converted into EPA and DHA
What is the function of AA EPA and DHA?
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
How are triglycerides formed?
Condensation reactions
Glycerol+3Fatty Acids= Triglyceride + H2O
What are the 3 categories that oils fall into?
Saturated Fat
Monosaturated
Polysaturated
- characterized by how much of each group it has.
- all oils are a mix of the 3
What are examples of oils rich in saturated fat?
Animal fats (butter, lard)
Tropical oils (coconut, palm)
What are examples of oils rich in monounsaturated fats?
Olive and canola oil
What are examples of oil rich in polysaturated omega 3 fats?
Flaxseed oil
What are examples of oil rich in polyunsaturated omega 6 fats?
Sunflower and corn oil
What is hydrogenation?
When you add H’s to unsaturated fatty acids causing the double bonds to break
What are the properties of hydrogenation
Makes liquid fat more solid at room temp
-does this by switching H configuration from cis to trans
Why was hydrogenation created?
Invented for shelf stability
What is a phospholipid?
Same as a triglyceride but instead of 3 fatty acids chains, on has a phosphate head
Where do we get our source of phospholipids?
Lecithin in eggs and soy
What is the function of phospholipids?
They act as emulsifiers, making something partially water and fat soluble
What is a characteristic about sterols?
Their ring structure
What is the most common sterol and how to we get it?
Cholesterol
We don’t need to get it from anywhere because we make it in the liver
In what food is cholesterol most common?
Only found in Animal fats
-plants have sterols
Why do we need cholesterol?
Need it to make other things our body needs
-bile acids, hormones and vitamin D
Structural components of the cell
Plaque formation
Why are plant sterols good?
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
What is the downside to plant sterols?
We don’t really absorb them that well
What is the process of lipid digestion?
- Mouth releases lingual lipase but digestion does not start here
- In the stomach, gastric lipase is present but digestion hasn’t really started yet
- In the small intestines, CCK is released which tells the pancreas to release enzymes, and tells the gallbladder to release bile
Why is bile important in lipid digestion?
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
What is a micelle?
emulsified fat droplet
-cuts off 2 fatty acid chains from the triglyceride to leave a monoglyceride
What are the 2 fates of bile after it has been used?
Reabsorbed and recycled
Excreted
Why is bile excretion good?
Since bile is made of cholesterol, if we excrete more then we are reducing the about the gets reabsorbed which intern increased blood cholesterol
When micelle crosses the cells in the small intestine wall, what will it have with it?
Tiny fat particles
All other fat soluble things such as vitamins
What happens after the micelle passes through the small intestine wall cells?
Triglycerides are put back together in an organized form called chylomicrons
What is a chylomicron?
Type of lipoprotein that transports fat throughout the body, composed of long chain triglycerides
-takes diet fat directly into the body
What is the fate of small and medium chain fatty acids after they have crossed the small intestine cell walls?
They go right into the blood straight to the liver
Where does the chylomicron go?
Into the lymphatic system, but enters the blood still as a chylomicron
What are the 3 types of lipoproteins and their characteristics?
- Chylomicron
- composed of a lot of dietary fat (light) and therefore not very dense - LDL
- carries cholesterol to cells in the body that need it. Mainly composed of cholesterol - HDL
- takes cholesterol out of the body, gets rid of it or uses it. Mainly composed of protein which is more dense
Why is LDL typically considered bad?
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
Why are lipids important
Need the triglycerides itself
Important because of the essential fatty acids
Protection
What are the roles of triglycerides?
Provide energy
Unlimited storage
Adipose tissue
Why is adipose tissue important?
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
How are triglycerides stored?
via Hydrolysis from Chylomicrons and VLDL by lipoprotein lipase
What is produced when fat is being used as an energy source?
Ketone bodies
usually when the body is fasting
What is the major health effect of lipids?
Heart disease
Why is heart disease linked to lipids?
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
What is the risk from eating too much saturated and trans fats?
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
What does saturated fat do to HDL?
Nothing really
What does trans fat do to HDL?
Makes HDL decrease
What is the DRI for fats?
20-35% of daily energy intake
What is the Daily recommendation for fats?
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
What is the mediterranean diet?
Diet of monounsaturated fats, lots of fish, veggies, and little red meats
Found to reduce the risk of chronic diseases
