Chapter 19, Problem 23P

Interpretation Introduction

Interpretation:

The compounds that can be lipids should be identified from the following:

Ribose, farnesol, pyruvic acid.

Concept Introduction:

Lipids are biomolecules which are involved in different biochemical reactions. They are special types of organic molecules which can only be identified with the help of their physical properties, not by the presence of any certain functional group.

In general, lipids contain a large number of C-C and C-H bonds with few polar functional groups such as −OH, -SH, etc., such as triacylglycerol consists of three ester groups whereas, Vitamin E is composed of both ether and phenolic groups.

Answer to Problem 23P

Correct answer: Option (b) is the correct answer.

Explanation of Solution

Reason for correct option:

Lipids are organic molecules composed of a large number of $\text{C-C and C-H}$ bonds with few polar functional groups. Because of bulky non-polar hydrocarbon part in the molecule, they are usually soluble in non-polar or weakly polar solvents. Here in the structure of farnesol, there is a long carbon chain with −OH as the functional group hence it should be a lipid molecule.

Conclusion

Reasons for incorrect options:

Ribose is a sugar molecule as it is a 5 membered ring with 4 −OH groups whereas pyruvic acid is a carboxylic acid. Since both molecules do not have large number of carbon atoms in the parent chain hence they are not lipid molecules.