Chapter 6, Problem 1TYK

How do the phospholipids in archaea differ from those in other cells?

a. They have tails made of unsaturated fatty acids instead of saturated fatty acids.

b. They do not contain hydrocarbon chains.

c. They have isoprenoid tails instead of fatty acid tails.

d. They have two hydrocarbon chains instead of three hydrocarbon chains.

Summary Introduction

Introduction:

A phospholipid is a class of lipid molecule that is the essential component of the cell membrane. Lipids are molecules that include fats, waxes, and some vitamins, among others. Each phospholipid molecule is made up of two fatty acids, a phosphate group, and a glycerol molecule.

Answer to Problem 1TYK

Correct answer:

They have isoprenoid tails instead of fatty acid tails.

Explanation of Solution

Explanation/Justification for the correct answer:

Option (c) is given as the archaeal phospholipids have isoprenoid tails. The archaeal phospholipids are different from the bacterial and the eukaryotic phospholipids. The bacterial and eukaryotic phospholipids are mainly made up of the glycerol ester lipids and fatty acid tails. The archaeal phospholipids are made up of the glycerol ether lipids along with isoprenoid tails. Hence, option (c) is correct.

Explanation for incorrect answers:

Option (a) is given as the tails are made up of unsaturated fatty acids. The saturated fatty acid chains are found in the archaeal phospholipids. Thus, the archaeal phospholipids do not contain the unsaturated fatty acid chains. The saturated fatty acid chains fuse with each other to form isoprenoid tails. Therefore, archaeal phospholipids do not have tails made of unsaturated fatty acids. So, it is a wrong answer.

Option (b) is given as they do not have hydrocarbon chains. The fatty acids of the archaeal phospholipids consist of the carboxyl group and a long chain made up of hydrocarbons. The hydrocarbons are the compounds that consist of molecules formed by the carbon C atom and hydrogen H atom. The fatty acid chains are also made up of the molecules formed by the atoms of carbon and hydrogen. Therefore, the fatty acid chains of the archaeal phospholipids are made up of the hydrocarbons. So, it is a wrong answer.

Option (d) is given as they have 2 hydrocarbon chains instead of 3. There are two long chains of saturated fatty acids connected to the glycerol linked with a phosphate group. These two chains fuse together to form the isoprenoid tails. Therefore, they do not have two hydrocarbon chains in their structure. So, it is a wrong answer.

Conclusion

The phospholipids in archaea differ from those in other cells in having isoprenoid tails instead of fatty acid tails.