Amoeba is a representative of unicellular animals that can actively move with the help of special specialized organelles. The structural features and the significance of these organisms in nature will be disclosed in our article.
Characterization of the kingdom
Despite the fact that protozoa have this 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.
Protozoan movement
Unicellular organisms move with the help of special organelles. In ciliates, they are called cilia. Just imagine: about 15 thousand of these organelles are located on the cell surface, up to 0.3 mm in size. Each of them makes pendulum-like movements.
Euglena has a flagellum. Unlike cilia, it makes helical movements. But what unites these organelles is that they are constant outgrowths of the cell.
The movement of the amoeba is due to the presence of pseudopods. They are also called pseudopodia. These are inconsistent cell 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 are sent inside the cell. As a result, the amoeba moves slowly. The presence of pseudopods is a hallmark of this representative of the Unicellular kingdom.
Amoeba 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, the human body and animals. This is a heterotrophic organism, the source of nutrition of which is unicellular algae and bacteria.
Amoeba structure
All protozoan cells are eukaryotic - contain a nucleus. The organs of the amoeba, or rather its organelles, are able to carry out all the processes of life. Pseudopods participate not only in the movement, but also provide the amoeba nutrition process. With their help, a unicellular animal covers a particle of food, which is surrounded by a membrane and is inside the cell. This is the process of the formation of digestive vacuoles, in which the breakdown of substances occurs. This method of absorption of solid particles is called phagocytosis. Undigested food debris is released anywhere in the cell through the membrane.
Amoeba, like all protozoa, does not have specialized respiratory organelles, carrying out gas exchange through the membrane.
But the process of regulation of intracellular pressure is carried out using contractile vacuoles. The salt 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 smaller one. Contractile vacuoles regulate this process, removing some metabolic products together with water.
Amebas are characterized by asexual reproduction by dividing the cell in two. This is the most primitive of all known methods, but it provides the exact preservation and transmission of hereditary information. In this case, the division of the nucleus, organelles, and then the isolation of the cell membrane first occurs.
This simplest organism is able to respond to the action of environmental factors: light, temperature, changes in the chemical composition of the reservoir.
Adverse conditions unicellular transferred in the form of cysts. Such a cell stops moving, the water content in it decreases, the pseudopods are drawn in. And she herself is covered with a very dense shell. This is a cyst. With the onset of favorable conditions, amoeba exit the cysts and go on to the usual processes of life.
Dysenteric amoeba
Amoeba is not only a harmless inhabitant of fresh water bodies, which is part of plankton. One of its species, called dysenteric amoeba, lives in the lumen of the human intestine. Here, a unicellular organism leads a parasitic lifestyle, eating bacteria. Penetrating into the intestinal wall, the amoeba destroys the cells of the mucous membrane and red blood cells - red blood cells. As a result, ulcers appear on the surface. Together with undigested food debris, parasitic animals go outside. You can get dysentery by drinking raw water, unwashed vegetables and fruits, without observing personal hygiene rules.
Many species of these protozoa play a positive role in nature. Amoebas are a source of nutrition for many animals, namely fish fry, worms, mollusks, small crustaceans. They clean fresh water from bacteria and rotting algae, are an indicator of the cleanliness of the environment. Shell amoeba took part in the formation of limestone and Cretaceous deposits.