Lipids Flashcards by Jhaunte Braithwaite

What are lipids?

Heterogenous class of biomolecules, soluble in non polar organic solvents

Small polymers

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Describe the polarity of lipids

Hydrophobic/nonpolar, some are amphipathic (contains both polar and non-polar regions)

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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

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What are the regions of fatty acids?

Polar and non-polar

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What are the most abundant fatty acids?

C-12 to C-20 and even numbered

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Describe the double bonds in fatty acids

Nit conjugated and are cis configuration

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How do fatty acids differ?

Differ by chain length, degree of unsaturation, position of double bonds

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What are fatty acids?

Moniccarboxylic acids with long non-polar hydrocarbon chains

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Explain the naming of fatty acids

Numbering from the carboxylic acid

- position of the double bond from the methyl end(omega system)

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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

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What is another name for arachidic acid, give number of carbons and M. Pt.

Eicosanoic acid

C20:0
M Pt= 77. degrees Celsius

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Give another name for stearic acid, giving M Pt and number of carbons

Octadecanoic acid

C18:O

71 degrees Celsius

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Give another name for palmitic acid, giving M. Pt. and number of carbons

Hexadecanoic acid

C16

63 degrees Celsius

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Give another name of myristic acid, number of carbons and M Pt.

Tetradecanoic acid

C14:O

58 degrees Celsius

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Give another name for Laurie acid, giving number of carbons and M. Pt

Dodecanoic acid

C12

MPt 44 degrees Celsius

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List 5 saturated fatty acids

Laurie

Myristic

Palmitic

Stearic

Arachadonic

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What are essential fatty acids?

Fatty acids that must be gained by diet as mammals cannot introduce bonds beyond C10

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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

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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

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Most fatty acids in living cells are _______ or in _____________ ________

Esterified

Amide. Linkage

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Fatty acids in living beings, little exists in…

As free fatty acids

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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

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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

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Simple TAG -3 fatty acids are….

The same such as tripalmitin or triolein

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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?

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