Question

Nucleolus is
A) Rounded structure found in cytoplasm near nucleus
B) Rounded structure inside nucleus and having rRNA
C) Rod-shaped structure in cytoplasm near the nucleus
D) None of the above

Answer 1

Hint: Nucleolus is a rare organelle as it is free of lipid bilayer. The nucleolus is a compact chromatin region where synthesis of the ribosome happens.

Complete answer:
First we should know about nucleolus to answer this question. The nucleolus is the distinct structure that comprises the genetic material in an organelle and defines the whole structure and function of eukaryotic cells. It mainly includes assembling the ribosomes, modifying RNA transfer and sensing cellular stress. Ribonucleic acid and proteins that form along particular chromosomal regions comprises the nucleolus.
Now, let us find the solution from the options-
>Nucleolus is not found in the cytoplasm, it is present in the nucleoplasm. Therefore, the option A is incorrect.
>The nucleolus is a small round body comprising RNA and proteins inside a nucleus. It is usually associated with a particular chromosomal site and is engaged in the synthesis of ribosomal RNA and ribosome formation. There would be no protein synthesis if the nucleolus did not exist, because there would be no ribosome production.
>It is neither rod-shaped nor found in cytoplasm. Therefore the option C is incorrect.
Thus, the correct answer is option (B) Rounded structure inside nucleus and having rRNA

Note:The nucleolus, occupying about 25 percent of the volume of the nucleus, is called the brain of the nucleus. Via an electron microscope, the nucleolus ultrastructure can be easily visualised. With the strategies of fluorescent restoration after photobleaching and fluorescent protein labelling, the structure of the nucleolus inside the cell can be clearly examined.