The small spherical body in the nucleus of a cell consisting of protein and RNA is called a nucleolus.

Here's a breakdown of its key functions:

* Ribosome Synthesis: The nucleolus is the site of ribosome biogenesis. It produces ribosomal RNA (rRNA) and assembles it with proteins to create the ribosomes, which are essential for protein synthesis.

* Regulation of Cell Cycle: The nucleolus plays a role in regulating the cell cycle, particularly in the transition from G1 to S phase.

* Stress Response: The nucleolus can also respond to cellular stress, such as DNA damage or nutrient deprivation.

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