frumukjarna

Frumukjarna, often translated as cell nucleus, is a membrane-bound organelle found in eukaryotic cells. It serves as the primary repository of the cell's genetic material, deoxyribonucleic acid (DNA), which is organized into chromosomes. The nucleus controls and regulates the activities of the cell, such as growth, metabolism, and reproduction, by controlling gene expression.

The nucleus is enclosed by a double membrane called the nuclear envelope, which separates its contents from the cytoplasm. This envelope is perforated by nuclear pores, which regulate the passage of molecules into and out of the nucleus. Within the nucleus is the nucleoplasm, a gel-like substance that contains the chromatin (DNA and associated proteins) and the nucleolus. The nucleolus is primarily involved in ribosome synthesis.

The process of DNA replication, where the cell's genetic material is copied before cell division, occurs within the nucleus. Transcription, the process of creating an RNA copy of a gene, also takes place in the nucleus. The RNA molecules then move out of the nucleus to the cytoplasm, where they are involved in protein synthesis. The presence of a distinct nucleus is a defining characteristic of eukaryotic organisms, differentiating them from prokaryotes, which lack a membrane-bound nucleus.