Amoeba is a representative of unicellular animals that can actively move with the help of special specialized organelles. The structural features and significance of these organisms in nature will be revealed in our article.
Characteristics of the subkingdom Protozoa
Despite the fact that the simplest have such a name, their structure is quite complex. After all, one microscopic cell is capable of performing the functions of the whole organism. Amoeba is another proof of this. This organism, up to 0.5 mm in size, is able to breathe, move, multiply, grow and develop.
Movement of protozoa
Single-celled organisms move with the help of special organelles. In ciliates, they are called cilia. Just imagine: on the cell surface, up to 0.3 mm in size, there are about 15 thousand of these organelles. Each of them makes pendulum movements.
Euglena has a flagellum. Unlike cilia, it makes helical movements. But what unites these organelles is that they are permanent outgrowths of the cell.
The movement of the amoeba is due to the presence of prolegs. They are also called pseudopodia. These are non-permanent cellular structures. Due to the elasticity of the membrane, they can form anywhere. First, the cytoplasm moves outward and a protrusion forms. Then the reverse process follows, the pseudopods go inside the cell. As a result, the amoeba moves slowly. The presence of pseudopods is a distinctive feature of this representative of the Unicellular subkingdom.
Ameba Proteus
Amoeba is an organism that got its name from one of the characters of Greek myths - Proteus, because he was able to change his appearance. This is a colorless unicellular animal that can be found in fresh water, soil, human and animal bodies. It is a heterotrophic organism that feeds on unicellular algae and bacteria.
The structure of an amoeba
All protozoan cells are eukaryotic - contain a nucleus. The organs of the amoeba, or rather its organelles, are capable of carrying out all life processes. Pseudopods are involved not only in the implementation of the movement, but also provides the process of nutrition of the amoeba. With their help, a single-celled animal covers a food particle, which is surrounded by a membrane and is inside the cell. This is the process of formation of digestive vacuoles, in which the breakdown of substances occurs. This way of absorbing solid particles is called phagocytosis. Undigested food residues are excreted anywhere in the cell through the membrane.
Ameba, like all protozoa, is nothas specialized respiratory organelles, carrying out gas exchange through the membrane.
But the process of regulation of intracellular pressure is carried out with the help of contractile vacuoles. The s alt content in the environment is higher than inside the body itself. Therefore, according to the laws of physics, water will flow into the amoeba - from an area with a higher concentration to a lower one. Contractile vacuoles regulate this process, removing some metabolic products with water.
For amoebas, asexual reproduction is inherent by cell division in two. This is the most primitive of all known methods, but it ensures the exact preservation and transmission of hereditary information. In this case, the division of the nucleus and organelles occurs first, and then the isolation of the cell membrane.
This simple organism is able to respond to environmental factors: light, temperature, changes in the chemical composition of the reservoir.
Single-celled organisms endure unfavorable conditions in the form of a cyst. Such a cell stops moving, the water content in it decreases, and pseudopods retract. And she herself is covered with a very dense shell. This is the cyst. When favorable conditions occur, amoeba leave the cysts and proceed to normal life processes.
Dysentery amoeba
Ameba is not only a harmless inhabitant of fresh water bodies, which is part of plankton. One of its species, which is called dysenteric amoeba, lives in the lumen of the human intestine. Here, a single-celled organism leads a parasitic lifestyle, feeding on bacteria. Penetrating intointestinal walls, the amoeba destroys the cells of the mucous membrane and red blood cells - erythrocytes. As a result, ulcers appear on the surface. Together with undigested food remnants, parasitic animals go outside. You can become infected with dysentery by drinking raw water, unwashed vegetables and fruits, without observing the rules of personal hygiene.
Many species of these protozoa play a positive role in nature. Amoebas are a source of food for many animals, namely fry of fish, worms, molluscs, small crustaceans. They clean fresh water from bacteria and rotting algae, and are an indicator of the purity of the environment. Testate amoebae have been involved in the formation of limestone and chalk deposits.
