Nucleoplasm: what is it, its parts and functions?

Let's see what this part of the cell looks like, what parts compose it, and what Biological functions it performs.

Have you ever heard of the nucleoplasm? It is the internal environment of the cell nucleus (the most important part of the cell), and supports many substances involved in cell metabolism and gene expression.

In this article we will learn about the structure, composition, appearance and most important functions of this specific part of the cell. First, however, we will review the concept of cell, and at the end of the article we will discuss the other components of the cell nucleus, beyond the nucleoplasm.

The cell as the basic unit

The cell is the basic unit of all living things; it is a microscopic structure, with the cell nucleus as the main component.. The human being is made up of millions and millions of cells, which are distributed throughout the body, making life possible.

In turn, the cell nucleus is made up of different components; one of them is the nucleoplasm, its internal, viscous medium.

But what exactly does this structure consist of, what are its characteristics, what is its appearance and composition, and what are its functions? We will answer all these questions in this article.

Nucleoplasm: what it is, and general characteristics

The nucleoplasm (which also has other names, such as nuclear cytosol, nuclear juice, nuclear matrix, karyoplasm or karyolymph) is the internal medium of the cell nucleus, which is semi-liquid in nature (has a viscous texture). (it has a viscous texture). In other words, it forms the inner part of the cell nucleus, which is the most important part of the cell (mainly because it contains the genetic material: DNA).

Within the nucleoplasm we can find two essential elements of the cell: DNA (genetic material) (in the form of fibers or chromatin) and RNA (ribonucleic acid) (in the form of fibers, known as nucleoli). Thus, we can say that this structure is made up of a series of elements that make genetic expression possible..

In terms of its appearance, the nucleoplasm has a viscous texture, and constitutes a semi-liquid medium. Its appearance is homogeneous, although it has a specific area that is less viscous, called hyaloplasm.

What do we find in the nucleoplasm?

Within the nucleoplasm are distributed different components of the cell nucleus, including: nucleotides (which enable the formation and replication of DNA), enzymes (responsible for directing the different activities developed in the nucleus itself) and the nucleolus (structure that transcribes the ribosomal RNA).

What is its structure?

The nucleoplasm is part of the living material of the cell (located inside the cell), which is called protoplasm..

Structurally, the nucleoplasm is enveloped by the nuclear membrane, which separates it from the cytoplasm. In addition, the nucleoplasm separates the chromatin from the nucleolus (structures that we will explain later).

Composition: various substances

In terms of composition, there are many substances that make up the structure of the nucleoplasm, or that are found within it. In fact, its composition is similar to that of the cell cytoplasm.

It should be noted that 80% of the nucleoplasm consists of water.. Water is its liquid phase, where organic compounds called compatible solutes are dispersed.

On the other hand, the nucleoplasm is also made up of proteins and enzymes related to the proteins and enzymes involved in the metabolism of nucleic acids (DNA). (DNA). In addition to these proteins, we also find others, called residual proteins, which are not bound to DNA or RNA, as are the previous ones.

Finally, the nucleoplasm is also made up of other substances, such as precursor molecules, small water-soluble molecules (related to cell signaling), cofactors (components necessary for enzymes to act) and substances involved in the process of glycolysis (through which we obtain energy from glucose).

Hormones and lipids

On the other hand, different hormones move through the nucleoplasm, bound to their respective nuclear receptors. These substances are steroid hormones and are basically the following: estrogen, testosterone, aldosterone, cortisol and progesterone..

We also find lipids in the nucleoplasm (specifically, they are suspended inside the cell nucleus), as well as phospholipids and fatty acids; the latter are involved in the regulation of gene expression.

Functions

We have seen the most relevant characteristics of the nucleoplasm, but what are its functions? Mainly, the nucleoplasm is the medium that enables the development of certain chemical reactions, essential for the metabolic functions of the cell nucleus..

These reactions are usually produced by the random movement of molecules. This movement is called "Brownian motion" and consists of random collisions between molecules suspended within the nucleoplasm. It is a simple, non-uniform diffusion movement.

On the other hand, the aqueous medium that forms the nucleoplasm also facilitates the activity of enzymes, as well as the transport of different substances necessary for the correct functioning of the nucleus and, by extension, of the cell. All this is largely due to its viscous texture..

Other parts of the cell nucleus

We have seen how the nucleoplasm forms part of the nucleus of any cell, and configures its internal medium of viscous or semi-liquid texture. However, the nucleus is also made up of other components, which are:

1. The nuclear envelope

This structure of the cell nucleus consists, in turn, of an outer and an inner membrane. Also called the nuclear membrane or karyotech, it is a porous structure that separates the nucleoplasm from the exterior. a porous structure that separates the nucleoplasm from the exterior..

2. The nucleolus

Also called the nucleolus, this is an area or structure within the cell nucleus, and has the function of transcribing ribosomal RNA.. It is also involved in cell cycle regulation, is involved in aging processes and regulates cellular stress responses.

3. Chromatin

Chromatin is a form of DNA presentation located in the cell nucleus. It consists of the basic substance of the chromosomes of eukaryotic cells (junction of DNA, RNA and proteins).. In turn, chromatin can take two forms: heterochromatin and euchromatin.

4. The ribosomes

The ribosomes are made up of RNA and ribosomal proteins, and enable the expression of genes.through a process called translation.

5. The NPC (nuclear pore)

Finally, another component of the cell nucleus is the NPC or cell pores, which constitute large protein complexes that cross the cell nucleus membrane.

Bibliographic references:

• Alberts et al. (2010). Molecular Biology of the Cell. (5th Ed.). Editorial Omega.
• Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. & Walter, P. (2002). Molecular Biology of the Cell (4th ed.). Garland Science, pp. 120-121.
• Feynman, R. (1970). The Feynman Lectures on Physics Vol I. Addison Wesley Longman.
• Jimenez, F. and Merchant, H. (2003). Cellular and Molecular Biology. Part II Cell Structures. Chap.13 Ribosomes. Pearson Educación, Mexico.
• Lodish et al. (2016). Cell and Molecular Biology. (7th Ed.). Editorial Médica Panamericana.