ET III Ch.23 Lipids

What are some simple lipids?

• Fats

• Oils

• Waxes

At room temperature what physical state are fats in?

Solids or semisolids

At room temperature what physical state are oils in?

Liquid

Hydrolysis of fats and oils yield what?

Fatty acids and glycerol

What are essential fatty acids?

• Fatty acids that our bodies need but are unable to synthesize

• Must be consumed in our diets

What is the general name for a fat or oil?

triglyceride

What is saponification?

Process of boiling fats or oils with aqueous alkali

What are the products of saponification?

Glycerol and metallic salts of fatty acids

What are metallic salts of fatty acids called?

Soap

Sodium stearates are commonly called?

Hard Soaps

How are hard soaps (sodium stearates) produced?

From the saponification of sodium hydroxide

What are potassium stearates commonly called?

Soft soaps

How are soft soaps (potassium stearates) produced?

From the saponification of potassium hydroxide

How do soaps work?

Soap molecules contain a non-polar portion and an ionic portion

• Dirt is mainly composed of oils and greases, typically non-polar

• Water is polar, therefore it won’t mix readily with dirt unless an emulsifying agent (soap) facilitates it

• Once emulsified, the water can carry the dirt away

Define emulsion

Mixture of two mutually insoluble substances

Define emulsifying agent

Substance which allows the mixture of two insoluble compounds

What are waxes?

Esters of fatty acids and high-molecular-weight alcohols rather than glycerol

What do waxes usually contain?

One hydroxy group per molecule

List some common waxes and what they are used for

• Beeswax (honeycomb) – cosmetics

• Lanolin (wool) – ointments and creams

• Spermaceti (heads of sperm whales) – candles

• Carnauba (palm leaves) – automobile and floor wax

When compound lipids are hydrolyzed what is produced?

Fatty acids, an alcohol, and other compounds

What are phospholipids composed of?

One molecule of glycerol, two fatty acid molecules, one phosphoric acid molecule, and an amino alcohol

What are cephalins?

Phospholipid where the amino alcohol is ethanolamine

• Important in the clotting of blood

What are lecithins?

Phospholipid where the amino alcohol is choline

• Helps transport fats from one tissue to another

• Egg yolk is a common source and added to foods as an emulsifying agent

Both lecithins and cephalins are found in nerve and _______ tissue

brain

What are sphingolipids?

Contain sphingosine, an unsaturated amino alcohol, a fatty acid unit, a phosphoric acid unit, and one or more cholines

• The simplest sphingolipid is sphingomyelin, a key component of brain tissue and the myelin sheath surrounding the axons of nerve cells

What are glycolipids?

Contain a sugar unit, usually galactose, as well as either glycerol or sphingosine, and fatty acids

• Glycolipids containing glycerol are found in plants and microorganisms

• Glycolipids with sphingosine are in brain and nervous tissues of animals

What type of lipid are terpenes

Derived lipids

What are terpenes?

Compounds containing carbon skeletons that are multiples of isoprene, a five-carbon unit

• The simplest terpenes contain two isoprene units

• Myrcene – found in bay leaves

• Zingiberene – found in oil of ginger

• Menthol – found in peppermint oil and used in many pharmaceuticals

What type of lipids are steroids

derived lipids

What are steroids?

• Miscellaneous lipids containing the parent structure called a cyclopentanophenanthrene nucleus

  • Steroid nucleus

• Contains three 6-membered rings and one 5-membered ring

What are sterols?

Steroids containing an alcohol functional group

What is cholesterol?

Most abundant sterol in the body, found in brain and nervous tissue, in the blood stream, and in gallstones

How do lipids play into embalming?

Fatty material may become rancid if microorganisms are not inhibited by embalming

• Lipids themselves don’t produce decomposition products

• If fats aren’t properly embalmed, they putrefy

What is adipocere?

• Commonly called grave wax

• White, waxy material produced by saponification of body fat when bodies are buried in alkaline soil

• Highly unlikely to happen with modern caskets and cemetery practices