Comprehensive Lipid and Fatty Acid Biology: Classification, Structure, and Function

What is a lipid?

An organic compound found in living organisms that is insoluble in water but soluble in nonpolar organic solvents.

How are lipids classified by biochemical function?

Into five categories: energy-storage lipids, membrane lipids, emulsification lipids, messenger lipids, and protective-coating lipids.

What are energy-storage lipids?

Triacylglycerols (TAG) that function as energy-storage molecules.

What are membrane lipids?

Phospholipids, sphingoglycolipids, and cholesterol that are integral to cell membranes.

What are emulsification lipids?

Bile acids that help in the digestion of fats.

What are messenger lipids?

Steroid hormones and eicosanoids that play roles in signaling.

What are protective-coating lipids?

Biological waxes that provide protection and waterproofing.

What is a fatty acid?

A naturally occurring monocarboxylic acid with a hydrocarbon side chain.

How are fatty acids classified?

By the number of carbons (long-chain, medium-chain, short-chain) and by the degree of unsaturation (saturated, monounsaturated, polyunsaturated).

What characterizes a saturated fatty acid?

It has a carbon chain with all carbon-carbon bonds as single bonds.

What characterizes a monounsaturated fatty acid?

It has one carbon-carbon double bond in its carbon chain.

What characterizes a polyunsaturated fatty acid?

It has two or more carbon-carbon double bonds in its carbon chain.

What affects the physical properties of fatty acids?

Carbon chain length and degree of unsaturation.

How does solubility change with carbon chain length?

Solubility decreases as carbon chain length increases.

What is the melting point trend for fatty acids?

The melting point increases with carbon chain length and decreases with the degree of unsaturation.

What are triacylglycerols?

Lipids formed by the esterification of three fatty acids to a glycerol molecule.

What is glycerol?

An alcohol containing three -OH groups.

What distinguishes fats from oils?

Fats are solid at room temperature and generally have a higher composition of saturated fats, while oils are liquid and have a higher composition of unsaturated fats.

What are the health implications of saturated fats?

They are considered 'bad fats' and are associated with an increased risk of heart disease.

What are phospholipids?

Lipids that contain fatty acids, a phosphate group, and a platform molecule, crucial for cell membranes.

What are the two types of phospholipids?

Glycerophospholipids (with glycerol) and sphingophospholipids (with sphingosine).

What is the general structure of glycerophospholipids?

They contain two fatty acids and a phosphate group esterified to a glycerol molecule.

What are steroids?

Organic molecules based on an interlocking four-ring structure consisting of one cyclopentane ring and three cyclohexane rings.

What are terpenes?

Polymers of isoprene.

What are waxes?

A type of lipid that serves as a protective coating.