Nucleolus

The nucleolus is a small, dense structure found within the nucleus of a cell. It plays a crucial role in producing ribosomes, which are essential for protein synthesis. The nucleolus assembles ribosomal RNA (rRNA) and combines it with proteins to form the subunits that make up ribosomes. While the nucleolus isn’t surrounded by a membrane, it becomes more visible when the cell is actively preparing to divide or produce proteins. Its activity is vital for the cell's overall function and growth.