Question

Which of the structures is not found in a prokaryotic cell?

• A. Mesosome
• B. Nuclear envelope
• C. Plasma membrane
• D. Ribosome

Answer 1

The correct option is B

Nuclear envelope

The correct option is B.

Explanation of the correct option:

1. In eukaryotic cells, the nuclear envelope (NE), a tightly controlled membrane barrier, separates the nucleus from the cytoplasm.
2. Many distinct proteins that have been connected to chromatin arrangement and gene regulation are present in it.
3. Organelles that are bound to membranes are absent from the nucleus of prokaryotic cells.
4. A prokaryotic cell lacks the nuclear membrane.
5. The double membrane layer that encircles the nucleus is known as the nuclear membrane.

Explanation of the incorrect options:

Option A:

1. A prokaryotic cell's mesosome is a convoluted, membranous structure created when the plasma membrane invaginates.
2. These additions aid in DNA replication, protein synthesis, and cell membrane formation.

Option C:

1. The membrane that divides the inside of the cell from the external environment is known as the plasma membrane, sometimes known as the cell membrane, and is present in all cells.
2. Identification, communication, control of solute exchange across the membrane, and separation of the cytoplasm from the surrounding environment are the four primary roles of the plasma membrane.

Option D:

1. The place where protein synthesis occurs in cells is called a ribosome, an intercellular structure consisting of both RNA and protein.
2. The messenger RNA (mRNA) sequence is read by the ribosome, which then converts the genetic code into a specific string of amino acids that develop into extended chains and fold to create proteins.

Final answer: The structure which is not found in a prokaryotic cell is the nuclear membrane.