Chapter 25, Problem 1TYU

Peptidoglycan is a chemical compound found in the cell walls of (a) most viroids (b) most archaea (c) all prokaryotes (d) most bacteria (e) most eukarya

Summary Introduction

Introduction: Bacteria and archaea are considered as prokaryotes in terms of lacking membrane-bound organelles, internal membranous structures, and cytoskeleton.

Answer to Problem 1TYU

Correct answer: Peptidoglycan is a chemical compound present in the cell walls of most bacteria. Hence, the correct answer is option (d).

Explanation of Solution

Reason for the correct answer:

The structures that are found in bacteria are the capsule, outer membrane, cell wall, plasma membrane, pilus, microcompartments, plasmid, endospores, and flagellum. The cell wall of most bacteria is made up of peptidoglycan layer. In Gram-positive bacteria, the cell wall is primarily composed of a thick layer of peptidoglycan. Gram-negative bacteria are surrounded by two membranes: outer thick membrane is made up of lipopolysaccharides and thin peptidoglycan layer.

Option (d) is given as “most bacteria”.

Bacterial cell wall is primarily composed of peptidoglycan. Hence, the correct answer is option (d).

Reason for incorrect answers:

Option (a) is given as, “most viroids”.

Viroids are the smallest infectious entities without a protein coat and cell wall. Hence, option (a) is incorrect.

Option (b) is given as, “most archaea”.

The cell wall of archaea lacks peptidoglycan. Instead it is composed of proteins and polysaccharides. Hence, option (b) is incorrect.

Option (c) is given as, “all prokaryotes”.

Archaea and bacteria are included under prokaryotes and as archaea lacks peptidoglycan in their cell walls. Thus, the statement “all prokaryotes have peptidoglycan in their cell walls” is not correct. Hence, option (c) is incorrect.

Option (e) is given as, “most eukarya”.

Peptidoglycan is not the component of cell walls of eukarya. Eukaryotic cell walls are composed of polysaccharide such as in plants (cellulose) and fungi (chitin). Hence, option (e) is incorrect.

Hence, the options (a), (b), (c), and (e) are incorrect.

Conclusion

Peptidoglycan is a component of most of the bacterial cell wall.