Concept explainers
Which of the following is not found in all bacterial cells?
- a. cytoplasmic membrane
- b. a nucleoid
- c. ribosomes
- d. actin-like cytoskeleton
Introduction:
Bacteria are prokaryotic organisms that either present in clusters of cells or as isolated form. The cell wall of bacteria is made up of peptidoglycan layer, they lack membrane bound organelles and exhibit asexual mode of reproduction.
Answer to Problem 1MCQ
Correct answer:
Actin like cytoskeleton is not found in all bacterial cells. Therefore, option (d) is correct.
Option (d) is given as “actin-like cytoskeleton”.
Explanation of Solution
Justify reason for the correct statement:
Structures that are found in some bacteria are S layer, fimbriae, outer membrane, cell wall, actin cytoskeleton, pilus, granule, microcompartments, plasmid, endospores and flagellum. Actin-like cytoskeleton is one of the structures that are not found in all bacteria. It consists of long protein fibers that encircle inside the plasma membrane and contribute to cell shape.
Hence, option (d) is correct.
Justify reasons for the incorrect statements:
Option (a) is given as “cytoplasmic membrane”.
Cytoplasmic membrane or cell membrane is a thin sheet of protein and lipid that surrounds the cytoplasm. It controls the flow of material in and out of the cell and found in all bacteria. Hence, it is a wrong answer.
Option (b) is given as “a nucleoid”.
It is also known as bacterial chromosome, composed of condensed molecules of DNA. DNA directs all the heredity and genetics of the cell and also codes for proteins. It is also present in all bacteria. Hence, it is a wrong answer.
Option (c) is given as “ribosomes”.
These are the tiny particles composed of RNA and protein. They are the site for synthesis of protein and present in all bacteria. Hence, it is a wrong answer.
Hence, options (a), (b), and (c) are incorrect.
The structure which is not found in all bacterial cells is actin like cytoplasm.
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Chapter 4 Solutions
Microbiology: A Systems Approach
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