Chapter 23, Problem 71A

Interpretation Introduction

Interpretation:

The type of lipid which doesn't contain fatty acid chains should be determined. The reason should be determined for the classification of those molecules as lipids.

Concept introduction:

The molecules which contains hydrocarbons and not soluble in water but soluble in nonpolar solvents is known as lipid.

Lipids are classified as:

Triglycerides, Phospholipids and, Steroids and Waxes

The type of lipid found in our blood is known as triglycerides. Triglyceride is obtained by the three glycerol molecules and three fatty acids.

Answer to Problem 71A

The type of lipid which doesn't contain fatty acid chains is steroid. Steroid is also hydrophobic in nature like lipids. Thus, steroids are classified as lipid.

Explanation of Solution

Fatty acid consists of carboxylic acid with long aliphatic chain which can be saturated or unsaturated. Generally, fatty acids exist as: phospholipids, triglycerides and cholesteryl esters. These are important structural components for cells. Thus, lipid contains fatty acids.

Some lipids don’t contain fatty acids chain but consist of cyclic rings such as steroid.

General structure of steroid contains 17 carbon atoms which are linked with each other in four fused rings, three rings contains six carbon atoms that is cyclohexane rings and one is five membered ring that is cyclopentane.

Thus, steroids are classified as lipids as like lipids they are also insoluble in water and hydrophobic in nature. But the structure of steroid is different from other lipids.