Nucleul

Nucleul (Romanian for nucleus) is the membrane-bound organelle in eukaryotic cells that houses the organism’s genetic material and coordinates many essential cellular activities. It is bordered by the nuclear envelope, a double membrane that creates a distinct environment separate from the cytoplasm. The envelope contains nuclear pores, which regulate the selective transport of proteins, RNA, and other molecules between the nucleus and cytoplasm. Under the envelope lies the nuclear lamina, a network of intermediate filaments that helps maintain nuclear shape and organize chromatin.

Inside the nucleus, chromatin—DNA wrapped around proteins—condenses into chromosomes during cell division. A prominent substructure, the nucleolus, is the site of ribosomal RNA synthesis and the assembly of ribosomal subunits, which are later exported to the cytoplasm for protein synthesis.

Functions of the nucleul include storing and protecting genetic information, regulating gene expression, and coordinating DNA replication. It acts as the control center for transcription, RNA processing, and the initial steps of ribosome production. The nucleus also plays a role in organizing chromatin structure to influence which genes are active at any given time.

Transport into and out of the nucleus is mediated by nuclear localization signals and transport receptors, ensuring selective import of proteins and export of RNA and ribosomal components. In many organisms, the nuclear envelope breaks down during mitosis and re-forms around daughter chromosomes, enabling proper cell division.

The concept of Nucleul reflects its Romanian linguistic form and its central role as a defining feature of eukaryotic cells.