Lecture 13 Lipids/Fats Flashcards
How many essential lipids are there?
2
List the dietary functions of lipids? (There’s 7)
- Concentrated source of energy
- Components of all cell membranes
– Every plant or animal cell membrane has fat in it - Precursor for hormones, bile, Vit D etc.
- Source of essential fatty acids
- Increase absorption of fat soluble vitamins
- Insulates organs and nerves
- Improve diet palatability
Why does fat go to the top?
Because its hydrophobic.
Whats most of our carcass made of?
Water
Why do we have an issue?
We have to figure out how to fix. We must make fat water soluble
What does 1g of dry glycogen bind to?
2g of H20
How much energy does 1g of anhydrous fat store? And what does this explain?
6.75 times more energy thank glycogen.
Explains why fat was evolutionary
advantageous as an energy storage
compared to CHO
What does omega mean?
Its ways we identify fatty acids
Whats the difference between oil and lard?
Melting point
Whats important to know in terms of energy in fat?
twice as much energy in fat as there is proteins and carbohydrates
Why is there so much more energy in fat? And per weight basis it contains more?
Because fat is more reduced. It has more hydrogen so the % of total molecular weight hydrogen makes more of a %
So when you are gonna burn a fuel the fuel that has more hydrogen in it is going to have more energy. Its more reduced, you get more hydrogen through the electrode transport chain. More potential for ATP.
How does a cell generate ATP?
Oxidate Phosphorylation.
Whats the key of the TCA cycle?
Kicks off NAD+ AND NADH
What do fatty acids contain more of compared to carbohydrates?
- Compared to carbohydrates, fatty acids
contain more hydrogen molecules per unit of carbon, thus, they are in a more reduced form
– Hydrogen: 1 positively charged proton and 1 negatively charged electron
Why do carbohydrates contain less energy than lipids?
- Carbohydrates are partially oxidized so they contain less potential energy (H+ and e-) per unit of carbon
Whats the functions of bodyfat?
- Cushions body organs
- Insulates the body
- Source of stored calories in times of
sickness or fast
How much does 1lb of adipose tissue contain in kcalories?
3500 kcalories
Name classification of lipids? (5)
1-Fats and Oils (Triglycerides)
2- Glycolipids
3- Phosphoglycerides
4- Steroids
5- Eicosanoids
Fatty acids can be divided into two groups, what are they?
-Saturated (dosnt contain any double bonds)
-Unsaturated(Contains at least 1 double bond)
Whats the chemistry of lipids?
Carbons must have 4 bonds around them
Can be a double bond
Carbon can attach to O,H or C in fats
Tell me a bit about carbon chains?
-Vary in length
-Vary in saturation
1-Saturated (or) 2- Unsaturated
In saturated carbon chains what are they like?
-Maximum hydrogens, no double bonds
-Typically solid at room temperature
In unsaturated carbon chains what are they like?
-At least one double bond
-Typically liquid at room temperature
-Location and orientation of double bonds (non-conjugated, conjugated: cis, trans)
In short chain fatty acids how many carbons is there and what are these know as?
2-6 Carbons - VFA’s
In medium chain fatty acids how many carbons is there?
8-12 Carbons
In long chain fatty acids how many carbons is there?
14-24 Carbons
As the chain length increases the……
Melting point increases
Fatty acids synthesised by plants and animals have how many carbons?
Has an even number of carbons, mostly long chain, 16-18 carbon fatty acids are most prevalent
What is good to know about fatty acids?
With a few exceptions, natural fatty acids:
-Contain an even number of carbon atoms.
-Have a carboxyl group (-COOH) at one end
-Have a methyl group (CH3) at the other end
Animals oils are typically…
Solid
Veg oils are typically….
Liquid
Whats the exceptions of veg oils in being liquid?
Cocoa butter
Palm Oil
Coconut Oil
What is fatty acid melting point markedly dependent on?
-Chain length
-Degree of saturation
Whats the melting point of stearic acid?
69.6 degrees Celsius
Whats the melting point of oleic acid? (This has one double bond)
13.4 degrees Celsius
Whats the melting temperature of palmitic acid? it has 16 Carbons.
its 6.5 degrees lower than that of steric acid (18 Carbons)
Melting point increases with…. and decreases with….
Increases with chain length
Decreases with number of double bonds
How many carbons does stearic acid have?
(Saturated) 18 Carbons
How much carbons does oleic acid have?
(Monounsaturated) 18:1 Carbons
How much carbons does linoleic acid have ?
(Polyunsaturated) 18:2 Carbons
How can individual fatty acids by identified?
It is an individual fatty acids can be identified by one of two numerical nomenclature systems. (Only trying to identify where the double bonds are)
Name the 2 nomenclature systems?
1= n- ω- omega Designation
2= ^ - delta Designation
For the nomenclature system n- ω- omega Designation what is this depreciated by?
Carbon numbering starts from methyl end
For the nomenclature system ^ - delta Designation what is this depreciated by?
Carbon numbering starts from carboxyl group
Whats the standard nomenclature molecule for n-Designation?
C20 : 4 Omega 6 fatty acid
Carbon:Number:Position of double bonds
Whats the standard nomenclature molecule for ^-Designation?
H20 : 4 Omega ^5,8,11,14 Fatty Acids
Carbon:Number:Position of double bonds
If you have a saturated nomenclature structure what are the bonds like?
Single bonds
If you have an unsaturated nomenclature structure what are the bonds like?
Double bonds
Whats effects stability?
Saturation
Why can unsaturated spoil?
It can spoil due to oxidation , its unstable
What do we do to protect products from “going off”?
– Air-tight seals
– Add antioxidants
– Saturate the product or partially-
hydrogenation
Whats Industrial Hydrogenation also known as?
Partial Hydrogenation
What is Industrial Hydrogenation
aka Partial Hydrogenation?
Reductive chemical reaction resulting in the addition of hydrogen atoms to the double bonds (primarily liquid vegetable oils)
What are end products of Industrial Hydrogenation aka Partial Hydrogenation like?
End products are rarely complete or specific and a variety of trans fatty acids are produced
Whats the objectives of Industrial Hydrogenation aka Partial Hydrogenation?
– Butter substitute during mid 19 th centry
– Production of semi-solid spread (1940’s)
– Supposedly “healthier” than butter (1960-90’s)
Whats hydrogenation “Trans” from?
Trans: from food processing and rumen biohydrogenation (via microbial
metabolism)
* Partial hydrogenation of polyunsaturated fats
* Lowers fluidity - becomes more solid at room temp.
Why do fats contain more energy than carbohydrates?
Fatty acids have more hydrogen than carbohydrates
What is kicked off the TCA cycle?
NADH and FADH2
What changes the shape of fatty acids?
Hydrogenation.
End up with a variety of polyunsaturated monounsaturated and saturated fatty acids.
List the functions of bodyfat:
- Cushions body organs
- Insulates the body
- Source of stored calories in times of
sickness or fast
How many calories does 1lb of adipose tissue have?
3500 kcalories
Name Unsaturated Fatty Acids:
1- Monounsaturated
2- Polyunsaturated
3- Transaturated
What type of fatty acids contain a little but more energy?
Saturated
On a Monounsaturated how many carbons are there and a double bond?
Carbons= 18
Double Bond= 1
On a Saturated Fatty acid, how many Carbons and Double bonds?
Carbons = 18
Double Bond = 0
In a polyunsaturated fatty acid, how many Carbons and how many double bonds?
Carbons= 18
Double bonds= 2
Name the 2 essential fatty acids:
-Linoleic (octadecadienoic)
-Linolenic (Octadecatrienoic)
Whats the composition of -Linoleic fatty acid (octadecadienoic)
C18 H32 O2
C18:2
What’s the composition of Linolenic fatty acid (Octadecatrienoic)
C18 H30 O2
C18:3
The more double bonds the more…
Liquid it would be at room temperature
The vat majority of the double bonds have a methyl group between then but our friend microbes don’t have a methyl group have between them…what does it mean?
conjugated bonds
What do some of the microbes create (what type of double bonds)
Trans (hydrogens are on the opposite side of each other) it is nearly straight.
What are the vast majority of bonds that we eat in what type of bond?
Cis
What does Cis mean?
Same side
What does Trans mean?
Opposite side
What do trans fats act more like?
Saturated fats
What is the trans fatty acid controversy?
- Trans fats can no longer be used in
restaurants in New York city and San
Francisco - Thought (although not proven) to cause
health problems for humans
– Heart disease
– Cancer
What does essential fatty acid deficiency cause?
- dry and flaky skin, and the coat actually
feels greasy and dull and has a coarse
texture
