We explain what the cell nucleus is and what its main characteristics are. In addition, the functions it fulfills and how it is structured.
What is the cell nucleus?
The cell nucleus is a small structure with a spheroid or oval appearance that is found (usually) in the center of the nucleus of eukaryotic cells and that contains all the genetic material of the organism.
It is the main organelle of cells and is considered the operational center because it is responsible for controlling cellular activities. In addition, it stores and maintains the integrity of all the genetic information of the organism so that, at the right moment, this information is transmitted to the daughter cells.
Within the cell nucleus are DNA and RNA molecules and structures such as the cell envelope and the nucleolus, which is a dense and spherical region of the nucleus that has the function of producing and assembling ribosomes .
Characteristics of the cell nucleus
Some of the main characteristics of the cell nucleus are:
- It is the largest organelle within the cell and its shape can be circular or ovoid.
- It is present only in eukaryotic cells of organisms, such as animals , plants, and fungi .
- It stores all the genetic information of the individual.
- It is the operational center of the cell.
- It is generally located in the center of the cell, although in some cases it can be found in the cell periphery.
- It is a fundamental part of the ribosome generation process.
- It is made up of different structures such as the nucleolus, chromatin and the cell envelope.
Functions of the cell nucleus
The cell nucleus is only found in eukaryotic cells , since prokaryotic cells are usually in unicellular organisms that are characterized by having the genetic material loose in the cytoplasm and not in a cell nucleus.
One of the main functions of this organelle is to store the genetic information of the organism , that is, to store the genes that are inside the DNA molecules and are part of the chromatin and, at the time of interface, organize them within chromosomes . This genetic information that the cell nucleus stores is essential in different vital processes such as cell division.
In addition, the nucleus is responsible for controlling cell activity , and within this structure the information from DNA is transcribed into ribosomal RNA, which has, among other functions, protein synthesis . This protein synthesis takes place in ribosomes, which are organelles that are in the cytoplasm of the cell and are created by the nucleolus within the cell nucleus.
Structure and elements of the cell nucleus
The main elements that make up the cell nucleus are:
- 1. Nuclear envelope or membrane . It is the element that covers the nuclear content, gives it structure and separates it from the cytoplasm. Its main function is to protect the nucleus and it is subdivided into: outer membrane and inner membrane. These membranes remain separated by a space called the "perinuclear space."
- Outer membrane . It is a rough-looking membrane due to the presence of ribosomes in its surface composition. It is located between the cytoplasm and the perinuclear space.
- Inner membrane . It is a membrane that does not contain ribosomes and is located between the perinuclear space and the nucleoplasm.
- 2. Perinuclear space and nuclear pores . The perinuclear space is the structure that is formed between the inner and outer membranes and is made up of nuclear pores that allow the passage of substances between the nucleus and the cytoplasm.
- 3. Nucleoplasm, karyolymph, or nuclear juice . It is the aqueous medium that is part of the interior of the cell nucleus and in which the chromatin and nucleolus are found. In addition, it is made up of water , molecules, hormones, enzymes , among others. Its main functions are: to hold the chromatin, the nucleolus and to be the medium in which chemical reactions of the metabolic process take place.
- 4. Chromatin . It is a substance that is made up of nucleoproteins and nucleic acids (DNA and RNA). DNA is condensed in chromatin, which is usually very long. During cell division, chromatin turns into thick structures called chromosomes. There are two types of chromatin:
- It is the chromatin with the highest level of condensation.
- It is the most abundant chromatin but has the lowest level of condensation.
- 5. DNA (deoxyribonucleic acid) . It is the nucleic acid that carries the genetic material that each individual has and is capable of replicating itself to transmit the morphological and physiological characteristics of the individual from generation to generation. DNA is in the nucleus of the cells of living beings and its structure resembles a double helix made up of two chains of nucleotides. In addition, a small portion of DNA is present in the mitochondria (cellular organelle that supplies energy).
- 6. RNA (ribonucleic acid) . It is the nucleic acid that is responsible for transmitting the vital information of DNA and for producing the proteins that cells need for their activity and development. It has a simple chain structure and there are different types depending on their function: messenger RNA, transfer RNA and ribosomal RNA.
- 7. The nucleolus . It is a structure that is part of the nucleus and is made up of proteins and synthesizes ribosomal RNA. It is dense and spherical and the number of nucleoli within the nucleus depends on each type of cell. Its main function is the assembly of ribosomes.
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