nucleilor

Nucleoli are small, dense structures found within the nucleus of eukaryotic cells. They are composed of proteins and RNA, and their primary function is to assemble ribosomes, the cellular machinery responsible for protein synthesis. Nucleoli are dynamic structures that can change shape and size in response to cellular needs, such as during cell division or in response to stress. They are typically visible under a light microscope as dark-stained regions within the nucleus. The nucleolus is surrounded by a structure called the nucleolar organizer region (NOR), which contains genes that encode ribosomal RNA (rRNA). These genes are transcribed into pre-rRNA, which is then processed and assembled into ribosomal subunits within the nucleolus. The nucleolus also plays a role in the regulation of gene expression and cellular signaling. In some cases, nucleoli can be disrupted or altered in shape, which can be indicative of certain diseases or cellular abnormalities. Overall, nucleoli are essential for the proper functioning of eukaryotic cells and play a crucial role in protein synthesis and cellular homeostasis.