Chapter 4, Problem 1MC

Which of the following is/are found only in prokaryotic cells?

1. a. plasmids
2. b. a cytoskeleton
3. c. mitochondria
4. d. ribosomes

Summary Introduction

Introduction:

Prokaryotic cells are the cells that do not contain a true nucleus or other cell organelles. All the unicellular organisms are the prokaryotes such as bacteria and archaea. Prokaryotic cells have nucleoid region instead of a true nucleus. Unlike eukaryotic cells, they have a cell wall. Prokaryotic cells are usually 0.1 to 5 micrometers in size. They have a large surface area because they are small in sizes, that makes them obtain a large amount of nutrients via plasma membrane.

Answer to Problem 1MC

Correct answer:

Plasmids are found only in prokaryotic cells. Therefore, option (a)  is correct.

Option (a) is given as “plasmids”.

Explanation of Solution

Justify reasons for the correct statement:

Plasmids are the autonomously replicating, double-stranded, extra-chromosomal DNA which is present mostly in the prokaryotic cells. However, sometimes they are also present in archaea and eukaryotes.

Hence, option (a) is correct.

Justify reasons for the incorrect statements:

Option (b) is given as “a cytoskeleton”.

A cytoskeleton is the complex network of protein filaments and tubules in the cytoplasm. It is present in all forms of cells, that is prokaryotic, eukaryotic or archaea. Hence, it is a wrong answer.

Option (c) is given as “mitochondria”.

Mitochondria is a membrane-bound cell organelle which is involved in the ATP production and it is exclusively found in the eukaryotic cells. Hence, it is a wrong answer.

Option (d) is given as “ribosomes”.

A ribosome is responsible for the protein synthesis, which is present in both prokaryotic and eukaryotic cells. Hence, it is a wrong answer.

Hence, options (b), (c), and (d). are incorrect.

Conclusion

Hence, plasmids are found only in prokaryotic cells