Nucleoid: What is, function and structure

The nucleoid, present in the prokaryotic cellsconstitutes a region with a non -uniform structure that contains most, or in its entirety, of the Genetic material of the cell. Unlike the nucleus of eukaryotic cells, this region lacks a nuclear membrane that delimits it.

According to investigations, the nucleoid is mostly composed of approximately one 60% DNAaccompanied by a Reduced amount of RNA and proteins. It is presumed that these last components, mainly messenger RNA and regulatory proteins, play a crucial role in the regulation of bacterial genome. The proteins associated with nucleoids, responsible for maintaining the highly rolled structure of nucleic acid, are distinguished from the histones found in the eukaryotic nuclei, since they do not form nucleosomes, where the DNA is screwed around a protein nucleus. Instead, these proteins usually use other mechanisms, such as DNA loops, to achieve the compaction of genetic material.

We recommend reading this article about the difference between DNA and RNA.

The nucleoid is a region inside the prokaryotic cells where the genetic material is located, mainly in the form of circular DNA. Although prokaryotic cells lack a defined nucleus surrounded by a nuclear membrane, the nucleoid performs several important functions for the cell. Some of these functions include:

• Storage of genetic material: The nucleoid houses the genetic material of the prokaryotic cell, which generally consists of a circular DNA molecule.
• DNA replication: In the nucleoid, DNA replication is carried out, a process by which the cell produces exact copies of its genetic material before cell division.
• RNA transcription: Transcription, which is the process of copying a specific DNA sequence in a Messenger Messenger MOlecule (RNM), can also occur in the nucleoid.
• Gene regulation: Although prokaryotic cells do not have a nucleus with a nuclear envelope such as eukaryotic cells, the nucleoid can play a role in the regulation of gene expression.

The nucleoid is formed by condensation and functional organization of a single chromosomal DNA molecule, with the help of chromosomal architectural proteins, RNA molecules and the overlap of the DNA itself. Likewise, it was shown that the final form of the nucleoid arises from a DNA hierarchical organization. DNA connections to DNA long and short range, formed within macrodominiums and among them, contribute to condensation and functional organization.

Bacteria have a group of proteins that bind to DNA, known as Nucleoid -associated proteins (NAP)which are analogous according to the histones of the eukaryotes. These proteins allow greater packaging without increasing the degree of overview of DNA.

NAP is rich in charged amino acids and are characterized by their low molecular weight. Some of the best known NAPs are H-NS (histone-like nucleoid-structuring), fis (investment factor stimulation), Hu (heat orstable protein), IHF (Integration Host Factor) and LRP (Leucine-Respect Regulatory Protein).

• Cell type: The nucleus is found in eukaryotic cells, which include animal, vegetable, fungus and protist cells. The nucleoid is present in prokaryotic cells, such as bacteria and arches.
• Nuclear membrane: The nucleus is surrounded by a nuclear membrane in eukaryotic cells, which separates the genetic material from the cytoplasm. The nucleoid is not surrounded by a nuclear membrane in prokaryotic cells. The genetic material is dispersed in the cytoplasm.
• Structure of genetic material: In the nucleus, the genetic material is highly organized in the form of chromosomes, which consist of Histonas DNA and proteins. In the nucleoid, the genetic material is generally circular DNA and is in a region less organized and associated with histones than in the nucleus.
• Size and complexity: The nucleus is a large and complex structure compared to the nucleoid. The nucleoid is smaller and less structured compared to the nucleus.
• Functions: The nucleus is the control center of the eukaryotic cell, where the DNA contains the genetic information and where the transcription of RNA and the replication of the DNA is carried out. The nucleoid in prokaryotic cells houses the genetic material and is the site where DNA replication and RNA transcription occurs.

Now that you know what the nucleoid is, we recommend you read this post about the cell nucleus: what it is, characteristics, parts and function.

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