Dedicating the publication again to biological topics, let's talk about one of the most important in it - the cytoskeleton (from the Greek "cytos", which means "cell"). We will also consider the structure and functions of the cytoskeleton.
General concept
Before talking about this topic, it is necessary to give the concept of cytoplasm. This is the internal semi-liquid environment of the cell, which is limited by the cytoplasmic membrane. This internal environment does not include the nucleus and vacuoles of the cell.
And the cytoskeleton is the framework of the cell, which is located in the cytoplasm of the cell. It is found in eukaryotic cells (living organisms containing a nucleus in cells). Is a dynamic structure that can change.
In some sources, considering the structure and functions of the cytoskeleton, a slightly different definition is given, formulated in other words. It is the musculoskeletal system of cells, which is formed by protein filamentous structures. Participates in cell movement.
Building
Let's consider the structure of this structure, then we will find out what functions the cytoskeleton performs.
The cytoskeleton was formed from proteins. Several systems are distinguished in its structure, the name of which comes from the main structural elements, or from the main proteins that make up these systems.
Since the cytoskeleton is a structure, there are three main components in it. They play an important role in the life and movement of cells.
The cytoskeleton consists of microtubules, intermediate filaments and microfilaments. The latter are otherwise called actin filaments. All of them are inherently unstable: they are constantly assembled and disassembled. Thus, all components have a dynamic balance with the proteins corresponding to them.
Cytoskeletal microtubules, which are a rigid structure, are present in the cytoplasm of eukaryotes, as well as in its outgrowths, which are called flagella and cilia. Their length can vary, some reach several micrometers in length. Sometimes microtubules are connected using handles or bridges.
Microfilaments are made up of actin, a protein similar to that found in muscles. In their structure, there are other proteins in small quantities. The main difference between actin filaments and microtubules is that some of them cannot be seen under a light microscope. In animal cells, they are combined in a plexus under the membrane and are thus associated with its proteins.
Microfilaments of animal and plant cells also interact with the protein myosin. At the same time, their system has the ability to reduce.
Intermediate filamentsare made up of various proteins. This structural component has not been sufficiently studied. It is likely that plants do not have it at all. Also, some scientists believe that intermediate filaments are an addition to microtubules. It has been precisely proven that when the microtubule system is destroyed, the filaments are rearranged, and with the reverse procedure, the influence of the filaments practically does not affect the microtubules.
Functions
Speaking about the structure and functions of the cytoskeleton, let's list how it affects the cell.
Thanks to microfilaments, proteins move along the cytoplasmic membrane. The actin contained in them takes part in muscle contractions, phagocytosis, cell movements, as well as in the process of sperm and egg fusion.
Microtubules are actively involved in maintaining the cell shape. Another function is transport. They carry organelles. They can perform mechanical work, which includes moving mitochondria and cilia. A particularly important role belongs to microtubules in the process of cell division.
They are aimed at creating or maintaining a certain cellular asymmetry. Under certain influence, microtubules are destroyed. This can lead to the loss of this asymmetry.
The functions of the cytoskeleton also include cell adaptation to external influences, processes of endo- and exocytosis.
Thus, we have considered what functions the cytoskeleton performs in a living organism.
Eukaryotes
Between eukaryotes andprokaryotes there is a definite difference. Therefore, it is important to consider the cytoskeleton of these animals. Eukaryotes (animals that have a nucleus in the cell) have three types of filaments.
Actin filaments (in other words, microfilaments) are located at the cell membrane. They take part in intercellular interaction and also transmit signals.
Intermediate filaments are the least dynamic part of the cytoskeleton.
Microtubules are hollow cylinders, they are a very dynamic structure.
Prokaryotes
Prokaryotes are unicellular organisms - bacteria and archaea, which do not have a formed nucleus. It was believed that prokaryotes do not have a cytoskeleton. But since 2001, active research on their cells began. Homologs (similar, similar) of all elements of the eukaryotic cytoskeleton were found.
Scientists have found that one of the protein groups of the bacterial cell skeleton has no analogues among eukaryotes.
Conclusion
Thus, we examined the structure and functions of the cytoskeleton. It plays an extremely important role in the life of the cell, providing its most important processes.
All cytoskeletal components interact. This is confirmed by the existence of direct contacts between microfilaments, intermediate filaments and microtubules.
According to modern concepts, the cytoskeleton is the most important link that unites various cellular parts and carries out data transmission.
