We explain what the cell nucleus is and the main functions of this organelle. Also, how each of its parts are composed.
What is the cell nucleus?
The cell nucleus is a membranous organelle found inside eukaryotic cells exclusively, and which contains the majority of the genetic material of the cell, organized in DNA macromolecules (called “chromosomes”), inside which, in certain positions called “loci”, the genes are found.
The cell nucleus operates as a cellular control tower, since its primary mission is to preserve the genetic material and put it into operation when necessary, such as in cell division or protein synthesis, since DNA contains the necessary pattern for all cell operations.
Interestingly, the cell nucleus was the first of the cellular organelles to be discovered through microscope observation. The first to take note of it was Anton van Leeuwenhoek (1632-1723), in salmon cells.
But the true function of the nucleus and its importance in heredity and cellular reproduction became evident much later, thanks to Mendel's laws and the discovery of cellular mitosis at the beginning of the 20th century.
The cell nucleus is one of the fundamental organelles of the cell, essential to achieve high levels of complexity of life as we are multicellular beings. In fact, the distinction between prokaryotic (more primitive) and eukaryotic (more evolved) cells is based on its presence or absence within the cell cytoplasm.
See also: Synapses
Functions of the cell nucleus
The core functions are:
- Contain and store chromosomes that carry genetic information (genes), especially during reproduction processes such as mitosis.
- Organize genes into specific chromosomes, which allows cell division and facilitates the transcription of its content.
- Allow the transport of molecules between the nucleus and the cytoplasm, selectively according to the size of the cells.
- Transcribe messenger RNA (mRNA) from the DNA matrix, which transports the genetic sequence to the cytoplasm and serves as a matrix for the synthesis of proteins that takes place within the cell.
- Produce ribosomes essential to create ribosomal RNA (rRNA).
Parts of the cell nucleus
The cell nucleus is covered by a membrane similar to the plasma membrane of the cell, which delimits its body and separates it from the outside. This membrane of the nucleus is known as nuclear envelope or karyoteca and has a series of pores that allow bidirectional movement between the nucleus and cytoplasm.
Another important component of the nucleus is the nucleolus a region of the nucleus abundant in chromatin and genetic material, which plays fundamental roles in cell division and in the biosynthesis of ribosomes, necessary for RNA.
In animal cells there is also a nuclear lamina that provides the nucleus with support and allows the organization of the chromosomes. This sheet consists of two fibrous networks of intermediate filaments composed of proteins, which are composed in the cell cytoplasm and then enter the nucleus.
Finally, there are subdomains of the nucleus about which little is known, that is, specialized compartments that are linked to various functions of the nucleus in ways that are not yet fully understood. These are the Cajal bodies, the interphase polymorphic karyosomal association, the promyelocytic leukemia bodies, and the “speckles.”
References
- Cellular and Molecular Biology. From Robertis Edward, Hib José. (2012) 16th ed. Promed Editorial.
- Biology: Solomon E., Berg L., Martin D. (2013) 9th Edition. Cengage Learning Publishing.
