Kap. 10.1 - Storage Lipids

Why are triacylglycerols used as stores fuels?

1. The carbon atoms of fatty acids are more reduced than those of sugars, so oxidation of triacylglycerols yields more than twice as much energy, gram for gram, as the oxidation of carbohydrates. 2. They are hydrophobic and therefore unhydrated --> the organism that carries stored fuel in the form of fat does not have to carry the extra weight of water of hydration that is associated with stored polysaccharides

The structure of waxes

Waxes are esters of long-chain fatty acids and long-chain alcohols

Do Adipocytes contain enzymes? if yes, which one and what is their function?

Yes, they contain lipase, that catalyze the hydrolysis of stored triacylglycerols, releasing fatty acids for export to sites where they are required as fuel

What are the melting point of biological waxes?

60°C to 100°C generally higher than those of triacylglycerols. .

polyunsaturated fatty acid (PUFA):

A fatty acid with more than one double bond, generally nonconjugated.

Definiton of a fatty acid

A long-chain aliphatic carboxylic acid in natural fats and oils; also a component of membrane phospholipids and glycolipids.

What can humans synthesis from ALA (omega-3 fra føden)

Can synthesize two other omega-3 PUFAs important in cellular function: 1. eicosapentaenoic acid (EPA; 20:5(Δ5,8,11,14,17), s 2. docosahexaenoic acid (DHA; 22:6(Δ4,7,10,13,16,19)).

Which configuration have almost all unsaturated fatty acids?

Cis configuration.

What do waxes serve as?

Energy stores and water repellents.

Lipases

Enzymes that catalyze the hydrolysis of triacylglycerols.

What are biologcal waxes (voks)?

Estes of long-chain (C14 to C36) sturated and unsaturated fatty acids with Long-chain (C16 to C30) alcohols.

What are the principal stored forms of energy in many organism?

Fats and oils

In unsaturated fatty acids, a cis double bond forces a kink in the hydrocarbon chain. what consequence has that?

Fatty acids with one or several kinks (knæk) cannot pack together as tightly as fully saturated fatty acids, and their interactions with each other are therefore weaker.

How is trans fatty acid produced?

Fermentation in the return of dairy animals are obtained from dairy products and meat.

The aim of Partial hydrogenation.

Forlænge holdbarheden af vegetabilske olier, der blev brugt til madlavning, og for at øge deres stabilitet ved de høje temperaturer, der blev brugt til friturestegning.

omega-3 (ω-3) fatty acids.

Have a double bond between C-3 and C-4

What are fatty acids a derivatives of?

Hydrocarbon

Melting point of unsaturated fatty acids

Is lower than saturated fatty acids of the same chain length Because less thermal energy is needed to disorder these poorly ordered arrays of unsaturated fatty acids.

How is the position of double bonds designated (betegnet) and will you write it?

It is designated ∆ (delta) a 20-carbon fatty acid with one double bond between C-9 and C-10 and another between C-12 and C-13 is designated: 20.2(∆^9,12)

Are the cellular oxidation of fatty acids exergonic or endothermic?

It is highly exergonic

What can be said in general of all fatty acids?

It is the hydrocarbon components of many lipids, They have an even number of carbon atoms (usually 12 to 24); they are either saturated or unsaturated, with double bonds almost always in the cis configuration.

What is lipids and where can their be extracted from?

Lipids are water-insoluble cellular components, of diverse structure, that can be extracted from tissues by nonpolar solvents.

Saturated (mættet) fatty acid

No double bonds

Chemical quality (fx hydrofrob og hydrofil) of triacylglycerols

Nonpolar, hydrophobic molecules, essentially insoluble in water

Adipocytes

Or fat cells. store large amounts of triacylglycerols as fat droplets that nearly fill the cell

What are the major structual elements of biological membranes?

Phospholipids and sterols

omega ω and its number

The carbon of the methyl group—that is, the carbon most distant from the carboxyl group. It is given the number 1 (C-1); the carboxyl carbon in this convention has the highest number

Are polyunsaturated fatty acids conjugated and if not, what sepearte them?

The double bonds of polyunsaturated fatty acids are almost never conjugated, but are separated by a methylene group

Which family of fatty acids are important for human?

The family of polyunsaturated fatty acids (PUFAs) with a double bond between the third and fourth carbon from the methyl end of the chain are of special importance in human nutrition.

How long can the body store glycogen as the energy supply?

The human body can store less than a day's energy supply in the form of glycogen.

A rule for determination of the solubility of fatty acids in water

The longer the fatty acyl chain and the fewer the double bonds, the lower is the solubility in water.

What is most common in fatty acids? (number, branched,)

The most commonly occurring fatty acids have even numbers of carbon atoms in an unbranched chain of 12 to 24 carbons

How is the physical properties of the fatty acids, and of compounds that contain them determined

They are largely determined by the length and degree of unsaturation of the hydrocarbon chain.

What can be said in general of triacylglycerols?

They contain three fatty acid molecules esterified to the three hydroxyl groups of glycerol. Simple triacylglycerols contain only one type of fatty acid; Mixed triacylglycerols, two or three types of fatty acid. They are primarily storage fats; they are present in many foods.

What do dietary trans fatty acids and why is it unhealthy?

They raise the level of triacylglycerols and of LDL ("bad") cholesterol in the blood, and lower the level of HDL ("good") cholesterol, and these changes alone are enough to increase the risk of coronary heart disease. But trans fatty acids may have further adverse effects, like to increase the body's inflammatory response --> another risk factor for heart disease

triacylglycerols / triglycerides/ fats/ neutral fats.

Triacylglycerols are composed of three fatty acids, each in ester linkage with a single glycerol

What are fatty acids in the blood plasma most present as?

carboxylic acid derivatives such as esters or amides

simple triacylglycerols

containing the same kind of fatty acid in all three positions. named after the fatty acid they contain fx. Simple triacylglycerols of 16:0, 18:0, and 18:1, for example, are tripalmitin, tristearin, and triolein, .

Partial hydrogenation function

converts many of the cis double bonds in the fatty acids to single bonds and increases the melting temperature of the oils so that they are more nearly solid at room temperature some cis double bonds are converted to trans double bonds

What do triacylglycerols form in eukaryotes?

form a separate phase of microscopic, oily droplets in the aqueous cytosol, serving as depots of metabolic fuel danner en separat fase af mikroskopiske, olieagtige dråber i den vandige cytosol, der tjener som depoter af metabolisk brændstof

What is the common pattern in the location of double bonds?

in most monounsaturated fatty acids the double bond is between C-9 and C-10 (Δ9), and the other double bonds of polyunsaturated fatty acids are generally Δ12 and Δ15.

Which form of omega-3 do humans require?

the omega-3 PUFA Δ-linolenic acid (ALA; 18:3(Δ9,12,15) in the standard convention) get it from the diet.