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Cell Nucleus Function

Cell Nucleus Function
The cell nucleus is an important component of eukaryotic cells. We have provided you the complete information about its structure and functions; along with a labeled diagram over here.
Saptakee Sengupta
Last Updated: May 31, 2018
Nucleus is a Latin word, meaning kernel. It's a spherical shaped organelle found only in eukaryotic cells and it contains the genetic material. The DNA molecules are organized in a linear fashion inside the nucleus. The nucleus when viewed under an electron microscope shows several sub structures, which carry out the function of gene expression and various other types of hereditary activities. Its functions are mainly associated with the genetic machinery of the body.
Structure of a Cell Nucleus
Before moving on to the functions of the nucleus, it's important to have a complete knowledge about its structure. It is a densely conglomerated cell organelle and every part has specific functions, which are common for both eukaryotic plants and animals. A cell nucleus contains the following parts:
  • Nuclear Membrane: Also known as nuclear envelope, it encloses the contents of the nucleus during the entire life cycle of the cell. Its inner lining is coated with proteins and the membrane disintegrates during cell division.
  • Nuclear Lamina: The nuclear lamina is composed of a meshwork of intermediate filaments which anchors nuclear pores and chromosomes and supports the nuclear envelope.
  • Chromosomes: They contain the genetic material of the cell. DNA molecules are embedded in the chromosomes. There are two types of chromatin, viz. euchromatin and heterochromatin present in the chromosome.
  • Nucleolus: This structure is densely stained in the nucleus and is devoid of nuclear membrane. Ribosomal DNA (rDNA) is present in the nucleolus in a region known as Nucleolar Organizer Region (NOR).
  • Nuclear Pores: The nuclear membrane is perforated with pores known as nuclear pores, which help in establishing communication between nucleus and cytoplasm.
Cell Nucleus Diagram
The functions of an animal cell nucleus and a plant cell nucleus are almost same. This is because the functions are categorized on the basis of prokaryotic and eukaryotic nature of the cells. A plant and an animal cell are both eukaryotic. Therefore, the functions of their nucleus are also same.

Compartmentalization of the Cell
Cell compartmentalization is the function of the nuclear envelope. It entails separation of the contents of the nucleus from the cytoplasm in order to maintain the identity of the nucleus. The nuclear envelope also separates the cytoplasmic process from the nuclear process and prevents translation of unspliced mRNA, which is a product of the mRNA splicing process.

Expression of Genes
One of the most significant functions of the nucleus is gene expression through DNA transcription. Thus, the nucleus is the site of transcription. It involves activity of different types of proteins that helps in unwinding of DNA, synthesis of the growing RNA molecules, super coiling of DNA and finally entering the actual transcription process. Proteins and other factors that assist and regulate transcription are helicase, RNA pol, topoisomerase, and transcription factors.

Processing of Pre-mRNA
The newly synthesized mRNA molecule, also known as primary transcript undergo post-transcriptional modification before getting exported to the cytoplasm. Post transcriptional modification takes place in the nucleus and it involves various biological processes like 3' poly adenylation, 5' capping and RNA splicing. These vital process are required before initiation of translation. Synthesis of ribosomes takes place inside the nucleus.

Nuclear Transport
Nuclear transport is carried out by the pores present in the nuclear envelope. The entry and exit of molecules is controlled by this structure. Cargo proteins are carried from the cytoplasm to the nucleus with the help of exportins while macromolecules like RNA are exported to the cytoplasm in association with importins and karyopherins. Thus, transportation takes place efficiently through the nuclear membrane.

Integration and Disintegration
Assembly and disassembly of the nucleolus is a characteristic feature of the process of cell division. Cell nucleolus function is basically associated with apoptosis or programmed cell death. Furthermore, the envelope and lamina of the nucleus undergo disintegration during the cell cycle. Duplication of chromosomes to form new genetic material of the daughter cells is an important function of the cell nucleus. Replication of DNA takes place inside the nucleus.

I hope the information on the functions of the cell nucleus has proven useful to you. The nucleus is the most important part of a cell as it is the site for synthesis of genetic material. The functional machinery is coordinated by various biochemical processes and a slightest variation in its function and structure can give rise to genetic disorders.