Lecture 11 - Lipids

The Role of Lipids:

Energy Storage

- Triacylglycerols

- Adipocytes

Structure

- Cell membranes

- Insulation

Signaling, Coenzymes, and Vitamins

- Lipid molecules can be cleaved to produce a signal

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Fatty Acids:

Saturated vs Unsaturated

# of carbons and degree of saturation determines?

Saturated - single, straight, solid (waxy) at room temp, pack tightly

Unsaturated - double, bent, and liquid (oil) at room temp, packed loosely

Physical properties

Fatty Acid Nomenclature:

Chain length : Number of double bonds

Numbering begins at the carboxyl carbon

Positions of double bonds are indicated by ∆ and a superscript number

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Naturally Occurring Fatty Acids:

Even numbers of carbon atoms in an unbranched chain of 12 to 24 carbons

Monounsaturated fatty acids --> double bond is usually between C-9 and C-10 (∆9)

Polyunsaturated fatty acids -->

- Double bonds are usually ∆12 and ∆15

- Double bonds are usually separated by a methylene group

- Double bonds are usually in the cis configuration

Have poor solubility

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Polyunsaturated Fatty Acids (PUFAs) contain how many double bonds in their backbone?

Examples found where?

More than 1

In omega fatty acids --> obtained through the diet

Triacylglycerol:

Simplest lipids constructed from fatty acids

Composed of? Ester bonds located?

Can be simple or mixed, what does each mean?

Non-polar, Hydrophobic

- Increased chain length increases or decreases solubility?

- Decreased double bond number increases or decreases solubility?

Composed of 3 FA and 1 Glycerol

Ester bonds between OH of carboxyl group of FA and the OH group of the glycerol

Simple = one kind of FA

Mixed = 2 or 3 different FA

- Increased chain length = decrease solubility

- Decreased double bond number = decrease solubility

Partial Hydrogenation:

Process that converts many of the cis double bonds in the FA to single bonds

Improves shelf life & increases stability

Increases the melting temperature

Coverts some cis double bonds to trans double bonds

Trans FA

- Raise the level of triacylglycerols in the blood

- Raise the level of LDL (bad) cholesterol in the blood

- Lower the level of HDL (good) cholesterol

- Increase the body's inflammatory response

Not done