Nucleoplasm: what it is, parts and functions

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

In this article we will learn about the structure, composition, appearance and most outstanding functions of this very specific part of the cell. Before, but, we will review the concept of cell, and at the end of the article we will talk about the rest of the components of the cell nucleus, beyond the nucleoplasm.

• Related article: "Major cell types of the human body"

The cell as a basic unit

The cell is the basic unit of every living being; 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 and viscous medium.

But what exactly does this structure consist of? What characteristics does it present? What is its appearance and composition? And its functions??? We will solve all these questions in this article.

Nucleoplasm: what it is, and general characteristics

The nucleoplasm (also called by other names, such as nuclear cytosol, nuclear juice, nuclear matrix, karyoplasm, or karyolymph) It is the internal environment of the cell nucleus, semi-liquid in nature (It has a slimy texture). That is, it forms the inner part of the cell nucleus, which is the most important part of cells (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 enable genetic expression.

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

• You may be interested: "Differences between DNA and RNA"

What do we find in the nucleoplasm?

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

What is its structure?

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

At the structural level, the nucleoplasm is surrounded 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

Regarding its 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.

Notably the nucleoplasm is made up of 80% water. Water is its liquid phase, where organic compounds called compatible solutes are found dispersed.

On the other hand, the nucleoplasm is also formed by proteins and enzymes involved in nucleic acid metabolism (DNA). Beyond these proteins, we also find others, called residual proteins, which are not bound to DNA or RNA, as the previous ones are.

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

Hormones and lipids

On the other hand, different hormones travel through the nucleoplasm, attached to their respective nuclear receptors. These substances are steroid hormones, and they are, fundamentally, 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.

• You may be interested: "Types of hormones and their functions in the human body"

Features

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 motion is called "Brownian motion" and consists of random collisions between molecules suspended within the nucleoplasm. It is a simple and non-uniform diffusion movement.

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

Other parts of the cell nucleus

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

1. The nuclear envelope

This structure of the cell nucleus is formed, in turn, by an outer and an inner membrane. Also called nuclear membrane or karyotheca, it is a porous structure that separates the nucleoplasm from the outside.

2. The nucleolus

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

3. Chromatin

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

4. Ribosomes

Ribosomes are made up of RNA and ribosomal proteins, and allow the expression of genes, through a process called translation.

5. The NPC (nuclear pore)

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

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.
• Jiménez, F. and Merchant, H. (2003). Cellular and molecular biology. Part II Cell structures. Chap. 13 Ribosomes. Pearson Education, Mexico.
• Lodish et al. (2016). Cellular and molecular biology. (7th Ed.). Editorial Médica Panamericana.