Lipids Flashcards
What are lipids?
Heterogenous class of biomolecules, soluble in non polar organic solvents
Small polymers
Describe the polarity of lipids
Hydrophobic/nonpolar, some are amphipathic (contains both polar and non-polar regions)
Give the classes of lipids and an example of each
Fatty acyl- fatty acids
Glycerlipids- acylglycerols
Glycerophospholipids- glycerphosphocholines
Sphingolipids- ceremides
Sterol lipids- sterols
Phenol lipids- quinones
Lipoproteins- transport form of lipids in plasma
What are the regions of fatty acids?
Polar and non-polar
What are the most abundant fatty acids?
C-12 to C-20 and even numbered
Describe the double bonds in fatty acids
Nit conjugated and are cis configuration
How do fatty acids differ?
Differ by chain length, degree of unsaturation, position of double bonds
What are fatty acids?
Moniccarboxylic acids with long non-polar hydrocarbon chains
Explain the naming of fatty acids
- Numbering from the carboxylic acid
- position of the double bond from the methyl end(omega system)
Give the types of fatty acids
Saturated vs unsaturated(mono or polyunsaturated fatty acids)
Short chain vs long chain fatty acids
Even vs odd chain fatty acids
Essential vs Non essential fatty acids
What is another name for arachidic acid, give number of carbons and M. Pt.
Eicosanoic acid
C20:0
M Pt= 77. degrees Celsius
Give another name for stearic acid, giving M Pt and number of carbons
Octadecanoic acid
C18:O
71 degrees Celsius
Give another name for palmitic acid, giving M. Pt. and number of carbons
Hexadecanoic acid
C16
63 degrees Celsius
Give another name of myristic acid, number of carbons and M Pt.
Tetradecanoic acid
C14:O
58 degrees Celsius
Give another name for Laurie acid, giving number of carbons and M. Pt
Dodecanoic acid
C12
MPt 44 degrees Celsius
List 5 saturated fatty acids
Laurie
Myristic
Palmitic
Stearic
Arachadonic
What are essential fatty acids?
Fatty acids that must be gained by diet as mammals cannot introduce bonds beyond C10
What are the essential fatty acids and from where are they obtained?
Linoleic and alpha-linolenic ( omega- 6 and omega -3) must be supplied from plant oils
What are the uses of the essential fatty acids?
Linoleic and alpha-linolenic acids( omega 6 and omega 3)
Used to produce arachidnic, y-linolenic and other polyunsaturated. C-20s
Most fatty acids in living cells are _______ or in _____________ ________
Esterified
Amide. Linkage
Fatty acids in living beings, little exists in…
As free fatty acids
What happens to free fatty acids in mammals?
Free fatty acids are released into blood by adipose tissue
They are transported in the blood, bound to albumin
How are fatty acids used for fuel molecules?
Stored are triacylglycerols I.e. esterified to glycerol
TAG’s are neutral, no charge, also hydrophobic
Well suited for stored-little hydration required- unlike glycogen
Simple TAG -3 fatty acids are….
The same such as tripalmitin or triolein
Most TAG are …
Mixed
What does existence of tricylglycerol (TAG) as a solid(butter) or liquid(oil) depend on?
Fatty acid composition
Contrast animal fat and olive oil
Animal fat- highly saturated
Olive oil-triolein
How are dialysis- and monoacylglycerols formed?
They are intermediates formed during hydrolysis of TAG’s
How can diacyl and monoacylglycerides form micelles?
Form micelles with bile salts
Why do diacylglycerides and monoacylglycerides have substantial solubility?
Due to free OH groups
Monoacylglycerides(2-mono) can be absorbed across….
The internal mucosa
What is saponification?
The base promoted hydrolysis of the ester linkages in fats and oil
Process converts insoluble TAG to soluble products
Explain the reaction, including reactants and products of basic hydrolysis of esterified fatty acids
-Dilute alkali (KOH or NaOH) break ester bond
Products:
-Glycerol
Fatty acid salts of Na+ or K+ to give soluble soap
Where do lipases act on TAG’s?
In cells and GI tract
Lipase and NaOH both hydrolyzed acylglycerols, give the difference in products
Lipase- ionized fatty acid ( RCOO-)
NaOH- sodium salt (3RCOONa+)
What are phospholipids?
Contain phosphate derived from phosphoric acid
What are the most common phospholipids?
Phosphoglycerides (Glycerophospholipids)
Describe the polarity of phospholipids
They are amphipathic molecules, contains both polar and non-polar molecules
Explain how is phosphatidic acid phosphoric acid produced?
A glycerol backbone with 2 OHs is esterified to fatty acids
The 3rd OH (A polar head group) is esterified to phosphoric acid, resulting in phosphatidic acid
Many phospholipids contain an additional ….
Alcohol esterified to the phosphoric acid group
How to name glycerophospholipids?
Names based on head group, X
All are glycerophospho (phosphatidyl) i.e, from parent compound
(Comeback to this slide)
Fatty acids are usually saturated at C1 and unsaturated at C2
What is the role of sphingolipids in the body?
Constituents of membranes in brain and nervous tissue
What are the 3 major families of sphingolipids?
Sphingomyelin
Cerebrosides
Gangliosides
Describe the structure of sphingolipids
One mole of sphingosine( an 18 carbon amino alcohol)( or a sphingosine derivative)
One mole of fatty acid
A polar head
Where are sphingosine not present?
In prokaryotes
Where is the fatty acid of a sphingolipids attached to?
Fatty acid attached to sphingosine base(C2) by an amide
Explain how sphingolipids are analogues of GP-lipids
C1, C2 and C3 of sphingosine correspond to the glycerol backbone of phospholipids
Basic structure of sphingolipids given by…
Ceremide
How is ceremides formed?
Sphingosine and fatty acid
Where is the polar head attached in sphingolipids?
The polar head group attached by a glycosidic bond(sugar) or by ester bond(phosphate)
This chemical is the main component of myelin sheaths surrounding certain nerves
Sphingomyelin
What combines to create sphingomyelin?
Ceramide and phospho-choline
What is the charge on sphingomyelin
Has no net charge(As it resembles phosphocholine)
Aside from myelin sheaths, where are sphingomyelin present?
In plasma membranes of most mammalian cells
What are glycosphingosides?
Ceremide linked to 1 or more sugar residues
What are gangliosides?
Glycosphingolipids with complex oligosaccharides head groups
Describe the sugar residues of ganglioside
At least 3. Residues, 1 Being sialic acid(N- acetylneuraminic) giving an anionic(-ve charge) to gangliosides
Describe gangliosides in relation to cell surfaces
On cell surfaces 2HC chains are embedded in P-membrane while oligosaccharides group on EC surface
Describe the bond in glycosphingosides
A beta glycosidic bond with C1 OH of sphingosine
Describe each of the 3 classes of glycosphingosides sides
Cerebrosides- galacto- and glucocerebrosides
Globisides- more than 1 sugar
Sulfatides- sulfate esters of cerebrosides
Give the 5 steroid classes and the number of carbons they have
Bile acids- 24
Corticosteroids - C-21
Progesterone- C-21
Androgens- C19
Estrogen - C18
Describe lipoproteins
Spherical macromolecules containing TAG, cholesterol, cholesterol esters in non-covalent associations with phospholipids and proteins
Do lipoproteins contain FREE fatty acids?
No
Describe the amphipathic nature of lipoproteins
Hydrophilic surface outside with a layer of amphipathic molecules- proteins, P-lipids, 3-OH of cholesterol
Hydrophobic core- cholesterol esters and TAG
What is the function of lipoproteins?
Transport of lipids in the blood
Give the 5 major classes of lipoproteins and their densities
Chylomicrons- below 0.95 g/mL
Very low density lipoprotein- 0.95 - 1.006 g/mL
Intermediate lipoproteins- 1.006-1.019 g/mL
Low density lipoproteins- 1.019- 1.063 g/mL
High density lipoproteins- 1.063- 1.210 g/mL
What are the lipid soluble proteins and their functions
Vitamin A/retinol - vision
Vitamin D - Ca and P metabolism
Vitamin K- blood clotting
Vitamin E- anti-oxidant, reproduction
Name 6 unsaturated fatty acids
Palmitoleic
Oleic
Linoleic
a-linolenic
y-linolenic
Arachidonic
What is another name for palmitoleic acid, giving single bond to double bond and M pt.
Hexadecenoic acid
C 16:1 (on carbon 9)
-0.5 degrees Celsius
Give another name for oleic acid, giving ratio of single to double bonds and M pt.
Octadecenoic acid
C18:1 on carbon 9
16 degrees celsius
Give another name for linoleic acid, giving ratio. Of single bonds to double carbon and M pt.
Octadecadienoic acid
C18:2 carbons 9 and 12
-5 degrees celsius
Give another name for a-linolenic acid giving ratio of double bond to carbon bond and M pt.
Octadecatrienoic acid
C18:3 carbons 9,12 and 15
-11 degrees Celsius
Give another name for y-linoleic, giving the ratio of double to single carbon bonds and M pt.
Octadecatrienoic
C18:3 on carbon 6,9 and 12
-13 degrees Celsius
Give another name for arachodonic acid, giving the ratio of double to single bonds and M pt.
Eicosatetraenoic
C20:4 on carbon 5,8,11,14
-50 degrees Celsius
