Chapter 17: Lipids

Chem 106

What is the structure and role of triacylglycerols?

3 fatty acids + 1 glycerol; major form of energy storage.

What are waxes and their function?

Fatty acid + long-chain alcohol; protective coating on plants/animals.

What is a sphinogomyelin (sphingophospholipid)?

Sphingosine + fatty acid + sugar; found in brain and nerve tissue.

What is a cholesterol and its function?

4-ring steroid; stabilizes membranes, precursor to hormones and bile salts.

What are bile salts?

Cholesterol derivatives; emulsify fats for digestion.

What are adrenocorticoid hormones and examples?

Steroids from adrenal glands; includes glucocorticoids (e.g., cortisol) and mineralocorticoids (e.g., aldosterone).

What are sex hormones?

Steroid hormones from cholesterol; includes estrogen, progesterone, and testosterone.

Structure of saturated fatty acids?

No double bonds; straight chains; solid at room temp.

Structure of monounsaturated fatty acids?

One double bond; kinked chain; liquid at room temp.

Structure of polyunsaturated fatty acids?

Two or more double bonds; more kinks; lower melting points.

Melting point trend of fatty acids?

Longer chain = higher MP; more double bonds = lower MP.

How to draw a triglyceride?

Draw glycerol + 3 ester-linked fatty acids (condensed or skeletal format).

What is hydrogenation of triglycerides?

Addition of H₂ to C=C bonds → converts unsaturated to saturated fat.

What is acid/enzyme-catalyzed hydrolysis of triglycerides?

Breaks ester bonds → glycerol + 3 fatty acids.

What is saponification?

Base hydrolysis of triglycerides → glycerol + soap (fatty acid salt).

Structure/function of the cell membrane?

Phospholipid bilayer; hydrophilic heads out, hydrophobic tails in; fluid mosaic model.

Function of cholesterol in membranes?

Maintains fluidity and stability of membrane.

What are lipoproteins?

Lipid + protein particles that transport lipids in blood.

Difference between LDL and HDL?

LDL = bad cholesterol (delivers to tissues); HDL = good (removes from tissues to liver).

What is the steroid core structure?

Four fused rings (three 6-membered, one 5-membered).