Amoeba is a representative of the simplest unicellular animals. A free-living cell of protozoa is able to independently move, feed, defend itself from enemies and survive in an unfavorable environment.

As part of the subclass "Roots" they belong to the class "Sarcode".

The rhizopod is represented by a wide variety of forms, among which there are three orders:

1. naked;
2. shell;
3. foraminifera.

The presence of a unifying feature - prolegs, allows testate and foraminifera to move in the same way as an amoeba moves.

In nature, the largest species diversity observed among the marine inhabitants of foraminifera - over a thousand species. There are significantly fewer shell forms of rhizopods - several hundred, they are often found in water, swamps, and mosses.

Skeletonized radiolarians are sometimes referred to as marine amoeba, although they are classified as a different subclass of Sarcodidae.

For medical practice, of interest are naked (ordinary) amoeba, in the structure of which there is no skeleton or shells. They live naked in both fresh and salt waters. The primitive organization of this organism is reflected in its species name "Proteus" ("Proteus" means simple, although there is an interpretation of this name referring to ancient greek god Proteus).

There are more than 100 species of Proteus, among them 6 species are described, found in different parts human body:

1. in the oral cavity;
2. in the small and large intestine;
3. in abdominal organs;
4. in the lungs.

All proteins consist of a single cell, the body of which is covered with a thin cytoplasmic membrane. The membrane protects a dense transparent ectoplasm, behind it is a jelly-like endoplasm. The endoplasm contains the bulk of the amoeba, including the vesicular nucleus. The nucleus is usually one, but there are also multinuclear species of organisms.

Proteas breathe throughout the body, waste products can be removed through the surface of the body, as well as through a specially formed vacuole.

The size of the common amoeba ranges from 10 microns to 3 mm.

Protozoa do not have sense organs, but they are able to hide from sunlight sensitive to chemical irritants and mechanical stress.

When there is no favorable conditions The vital activity of the protea forms a cyst: the shape of the amoeba is rounded, and a protective shell is formed on the surface. Processes inside the cell slow down until favorable times arrive.

Features allows the animal body to form cytoplasmic outgrowths with various names:

• pseudopodia;
• rhizomes;
• pseudopods.

Proteus pseudopodia are in constant motion, changing shape, branching, disappearing and re-forming. The number of pseudopodia is not constant, it can reach 10 or more.

Travel and nutrition

The rhizopods ensure the movement of the single-celled amoeba and the capture of food found. Regardless of the habitat, the amoeboid movement consists in the protrusion of the rhizome in a certain direction and the subsequent flow of the cytoplasm into the cell. Then pseudopodia are again formed in another place. There is a constant imperceptible flow of the body in search of food. This way of moving does not allow proteins to have a fixed body shape.

In the variety of forms taken by proteas in motion, there are up to 8 types. The characteristics of the types are determined by the shape of the cell and the type of branching of the pseudopodia during movement.

The type of movement chosen by the animal mainly depends on the composition of the aquatic habitat, which is influenced by the content of salts, alkalis and acids.

Proteas are omnivorous, feeding by phagocytosis. Food for this heterotroph can serve:

• bacteria;
• unicellular algae;
• small protozoa.

The process of feeding begins in motion as soon as the animal detects potential prey nearby. The body of the protozoan forms several pseudopodia that surround the found object and form a closed cavity.

Digestive juice is released from the cytoplasm into the resulting area - a digestive vacuole is formed. After digestion of nutrients, undigested food residues are thrown out.

Role in biocenoses

For billions of years, protozoa have been actively involved in the formation of the Earth's biosphere, being a necessary consumer in the food chain of various biocenoses.

The ability of the amoeba to move independently allows it to regulate the number of bacteria and pathogens on which it feeds. Biocenoses of sewage silt deposits, peat and swampy soils, fresh and sea waters are impossible without the participation of the simplest organisms.

Even a pathogenic dysentery amoeba in the intestinal biocenosis does not harm a healthy host organism, feeding on a variety of bacteria. And only organic lesions of the intestinal mucosa allow it to move into circulatory system and switch to erythrocyte nutrition.

In natural biocenoses, protozoa serve as food for fish fry, small crustaceans, worms and hydras. Those, in turn, serve as food for larger creatures. Thus, amoeba become participants in the movement of the circulation of substances.

amoeba proteus or amoeba common- lat. Amoeba proteus, belongs to the type of simple unicellular organisms.

The structure of an ordinary amoeba

Amoebas have a fairly simple body structure. If you look at the amoeba under a microscope, you can see that it consists of a gelatinous substance, that is, protoplasm and a nucleus inside. From the course of botany it is known that protoplasm with a nucleus inside forms a cell. This means that an ordinary amoeba can be safely called a unicellular organism, consisting of protoplasm and a nucleus inside.

The shape of the body of an ordinary amoeba is constantly changing, hence the name "amoeba", which is translated from Greek- "changing". The change in the shape of the body occurs due to the stretching pseudopods, which serve to move and capture food particles.

Habitat of an ordinary amoeba

Amoeba proteus are widely distributed throughout the globe, are most commonly found in fresh water and aquariums, but can also be found in puddles and ditches. Amoebas ordinary can survive even in the most adverse conditions. If living conditions worsen, for example, when a reservoir dries up, amoebas become covered with a special shell called a cyst, which can tolerate both high temperatures (up to +60 degrees) and low temperatures (up to -273 degrees). If living conditions improve, then the amoeba begins to move and feed again. What makes amoebas and other protozoa one of the most survivable organisms on the planet.

Amoeba locomotion

The movement of the amoeba is carried out due to the so-called pseudopods, which can appear anywhere in the body of the amoeba. When moving, the pseudopods are extended in accordance with the direction of movement of the amoeba, and gradually the protoplasm of the amoeba is poured into the elongated process (pseudopod), thereby creating movement along the surface. As a rule, during the movement of an ordinary amoeba, several processes (pseudopods) appear that differ in shape and size. The diversity in size and shape is associated with the absence of a shell in the amoeba proteus.

Nutrition of the common amoeba

common amoeba it feeds with the help of special retractable processes or pseudopods, and thanks to which, as mentioned above, it moves. When food enters the protoplasm through the pseudopods, a drop of liquid is formed around the food particle, called the digestive vacuole. Protoplasm secretes digestive juices into the digestive vacuoles, under the influence of which food is digested. Undigested food particles are excreted anywhere in the protoplasm.

Amoeba ordinary or amoeba proteus feeds on microscopic fungi, bacteria and algae.

Breath of amoeba proteus

In addition to nutrition, amoeba, like all living organisms, needs oxygen. If you move an amoeba into boiled water, you will notice that after a while the common amoeba dies due to lack of oxygen. From this we can conclude that amoeba absorb oxygen from water and release carbon dioxide.

Amoeba respiration is carried out by the entire surface of the body, due to the contractile vesicle or vacuole that appears inside the body. Which periodically increases, then decreases, or completely disappears. The contractile vacuole, after assimilation of oxygen, consists of water and carbon dioxide dissolved in it, and various kinds of substances unnecessary for the amoeba. When the bubble contracts, these substances and carbon dioxide are removed to the outside.

Reproduction of the common amoeba

Reproduction occurs by cell division. During division, the common amoeba stops moving, and the contractile vacuole also disappears. During reproduction, the core of the amoeba first slightly lengthens and then divides in half. Next, the protoplasm is divided. As a result, two daughter amoebas appear, which in a short period of time grow to the size of an adult amoeba.

Among the simplest organisms, the amoeba is considered the most primitive. Bacteria are microscopic in size and are single-celled creatures.

Amoeba is the simplest single-celled creature

Amoeba - what is it?

Amoeba (rhizome)- the lowest rank of living beings. What is it - a bacterium or an animal? The microorganism belongs to the simplest unicellular animals, has tiny sizes(from 0.2 to 0.5 mm), the shape of the body changes all the time depending on external conditions. Single-celled creatures, like more complex animals, use oxygen for breathing, and external environment release carbon dioxide.

Kinds

Under adverse conditions (temperature fluctuations, ponds drying up, air currents), it goes into sleep mode, transforming into a cyst

Amoebas enter the human or animal body in the form of a cyst, which is protected by a strong two-layer membrane. Infection occurs through food (poorly washed fruits and vegetables), contaminated water, dirty hands.

Structure

The amoeba does not have a skeleton, a mouth, lungs and gills.

Its structure is made up of organelles:

• big core;
• cytoplasm, clearly divided into two zones - ectoplasm and endoplasm;
• pseudopodia (false legs with which the cell moves);
• digestive vacuole;
• contractile vacuole (removes excess water and food from the body of the amoeba).

What an amoeba looks like and what it consists of is shown in the photo.

Amoeba has a simple structure

Nutrition

The rhizopod feeds on pseudopodia. The process of taking in solid food is called phagocytosis. The capture of food is part of the main functions of the false legs: they wrap around edible particles, which helps the latter to get into the nutrient vacuole, where the membrane envelops them. Gradually, digestion occurs, the excess of which exits the contracting vacuole during the movement of the amoeba.

The process of capturing food by an amoeba

reproduction

Amoeba can only reproduce asexually. Having reached maturity, the cell begins to divide, which results in 2 daughter organisms.

How they reproduce:

• change in the core (first it stretches, then it lengthens, as a result of which it is pulled in the middle);
• division of the nucleus into two halves (formation of two independent nuclei);
• the division of the amoeba itself into two new cells, each of which has its own nucleus.

Amoeba reproduce asexually

During the appearance of a daughter microorganism, the formation of organelles missing for a new cell occurs. In 24 hours, an amoeba can go through the process of binary fission several times.

Life cycle

The amoeba has a simple cycle of existence. In a favorable environment, cells develop, grow and divide asexually. With the deterioration of the conditions of existence, the amoeba "freeze", thereby forming cysts. Once in the body of a person, animal, in water bodies or moist soil, microorganisms come to life, are released from the protective shell and begin to multiply actively.

When the environmental conditions deteriorate, the amoeba becomes covered with a protective shell (cyst)

Amoebiasis symptoms

Symptoms of amoebiasis largely depend on the type of disease:

1. Intestinal amoebiasis (dysentery amoebic colitis, amoebic dysentery). Characteristic symptoms: copious diarrhea streaked with blood, mucus and pus. As the disease progresses, the negative manifestations in the form of fever, chills, vomiting, loss of appetite. During bowel movements, cramping pains in the lower abdomen are possible, which are less pronounced in a calm state.
2. Extraintestinal type of disease - occurs as a complication of intestinal amoebiasis. Most often affects the liver (abscess or amoebic hepatitis). Symptoms: enlargement of the affected organ, pain in the right hypochondrium, the appearance of jaundice, high temperature (up to 40 degrees).

When amoebas damage the liver, pain appears in the right hypochondrium

Amebiasis has a mild course (fever, diarrhea, yellowness on the skin) and manifests itself already in the later stages of the disease in the form of a breakthrough of purulent formations (peritonitis). This threatens to damage the lungs, brain, genitourinary system.

Diagnostics

The basis for the diagnosis of amoebiasis is 2 main methods:

• bacteriological analysis of biological material (cysts are looked for in feces);
• endoscopic examination of the rectum (detection of the degree of damage to the intestinal mucosa).

Only after confirming the diagnosis, the specialist prescribes the necessary treatment, taking into account all the features and severity of the disease.

An endoscopic examination is used to determine the degree of damage to the rectum.

Amoebiasis treatment

Drugs that adversely affect amoebas are divided into 2 main groups:

• contact (translucent) - Clefamid, Paromomycin, Etofamide - are used for asymptomatic amoebiasis, as well as for the prevention of relapses;
• tissue - Tinidazole, Ornidazole, Metronidazole - are prescribed for intestinal amoebiasis, as well as in the treatment of abscesses in the liver, lungs, and brain.

An intestinal disease caused by amoebas responds well to therapy and is almost completely cured in the early stages of the pathology.

Metronidazole helps with intestinal amoebiasis

Prevention

Infection with protozoa can be prevented by following simple preventive measures:

• use only boiled water (boil for at least 10 minutes);
• wash fruits and vegetables well before use;
• make sure that flies do not sit on food (cover with a protective film);
• adhere to the rules of personal hygiene (wash hands after using the toilet, before eating, after visiting public places and walking on the street);
• do not fertilize the beds with human feces.

It is important to have regular check-ups and not to ignore any unpleasant symptoms. This is the only way to protect yourself from a serious illness.

Amoeba are the simplest animals that consist of one cell. Among primitive microorganisms there is a dangerous species - dysenteric amoeba (not to be confused with malaria pathogens), which causes a dangerous intestinal disease amoebiasis. If the pathology is not detected in time, it can lead to severe complications in the liver, lungs and even the brain. Prevention and timely access to a specialist make it possible to prevent dangerous consequences.

The common amoeba (kingdom Animals, subkingdom Protozoa) has another name - Proteus, and is a representative of the Sarcode free-living class. It has a primitive structure and organization, moves with the help of temporary outgrowths of the cytoplasm, often referred to as pseudopods. Proteus consists of only one cell, but this cell is a complete independent organism.

Habitat

The structure of an ordinary amoeba

Amoeba ordinary - an organism consisting of one cell leading an independent existence. The body of the amoeba is a semi-liquid lump, 0.2-0.7 mm in size. Large individuals can be seen not only through a microscope, but also with an ordinary magnifying glass. The entire surface of the body is covered with cytoplasm, which covers the nucleus pulposus. During the movement, the cytoplasm constantly changes its shape. Stretching in one direction or the other, the cell forms processes, thanks to which it moves and feeds. It can push off algae and other objects with the help of pseudopods. So, in order to move, the amoeba stretches the pseudopod in the right direction, and then flows into it. The speed of movement is about 10 mm per hour.

The proteus does not have a skeleton, which allows it to take any form and change it as needed. The respiration of the common amoeba is carried out by the entire surface of the body; there is no special organ responsible for the supply of oxygen. During movement and feeding, the amoeba captures a lot of water. Excess fluid is excreted by a contractile vacuole that bursts to expel water and then re-forms. The amoeba has no special sense organs. But she tries to hide from direct sunlight, is sensitive to mechanical stimuli and some chemicals.

Nutrition

Proteus feeds on unicellular algae, rotting residues, bacteria and other small organisms, which it captures with its pseudopods and draws into itself so that the food is inside the body. A special vacuole is immediately formed here, where the digestive juice is secreted. Amoeba nutrition can occur anywhere in the cell. At the same time, several pseudopods can capture food, then the digestion of food occurs immediately in several parts of the amoeba. Nutrients enter the cytoplasm and go to build the body of the amoeba. Particles of bacteria or algae are digested, and the remains of vital activity are immediately removed to the outside. The common amoeba is capable of throwing out unnecessary substances on any part of its body.

reproduction

Reproduction of the common amoeba occurs by dividing one organism into two. When the cell has grown enough, a second nucleus is formed in it. This serves as a signal to divide. The amoeba stretches out, and the nuclei diverge on opposite sides. Approximately in the middle there is a constriction. Then the cytoplasm in this place bursts, so there are two separate organisms. Each of them contains a nucleus. The contractile vacuole remains in one of the amoebas, and a new one arises in the other. During the day, the amoeba can divide several times. Reproduction occurs in the warm season.

Cyst formation

With the onset of cold weather, the amoeba stops eating. Its pseudopods are retracted into the body, which takes the form of a ball. A special protective film- cyst (of protein origin). Inside the cyst, the body is in hibernation, does not dry out and does not freeze. In this state, the amoeba remains until the onset of favorable conditions. When the reservoir dries up, the cysts can be carried by the wind over long distances. In this way, amoeba settle in other water bodies. With the onset of heat and suitable humidity, the amoeba leaves the cyst, releases pseudopods and begins to feed and multiply.

The place of the amoeba in wildlife

The simplest organisms are a necessary link in any ecosystem. The importance of the common amoeba lies in its ability to regulate the number of bacteria and pathogens on which it feeds. The simplest unicellular organisms eat decaying organic remains, maintaining the biological balance of water bodies. In addition, the common amoeba is food for small fish, crustaceans, and insects. And those, in turn, are eaten more big fish and freshwater animals. These same simple organisms serve as objects scientific research. Large accumulations of unicellular organisms, including the common amoeba, participated in the formation of limestone, chalk deposits.

Amoeba dysentery

There are several varieties of protozoan amoebas. The most dangerous for humans is the dysenteric amoeba. It differs from the ordinary one in shorter pseudopods. Once in the human body, the dysenteric amoeba settles in the intestines, feeds on blood, tissues, forms ulcers and causes intestinal dysentery.

Amoeba habitat

The common amoeba is found in the mud at the bottom of ponds with polluted water. It looks like a small (0.2-0.5 mm), colorless gelatinous lump, barely visible to the naked eye, constantly changing its shape ("amoeba" means "changeable"). It is possible to consider the details of the amoeba structure only under a microscope.

The structure and movement of the common amoeba

The body of the amoeba consists of a semi-liquid cytoplasm with a small bubble-like nucleus enclosed inside it. The amoeba consists of one cell, but this cell is a whole organism leading an independent existence.
The cytoplasm of the cell is in constant motion. If the current of the cytoplasm rushes to one point on the surface of the amoeba, a protrusion appears on its body in this place. It increases, becomes an outgrowth of the body - a pseudopod, the cytoplasm flows into it, and the amoeba moves in this way. Amoeba and other protozoans capable of forming pseudopods are classified as rhizopods. They got this name for the external resemblance of the pseudopods to the roots of plants.

Amoeba food

An amoeba can simultaneously form several pseudopods, and then they surround food - bacteria, algae, and other protozoa. Digestive juice is secreted from the cytoplasm surrounding the prey. A vesicle is formed - a digestive vacuole.
Digestive juice dissolves some of the substances that make up food and digests them. As a result of digestion, nutrients, which seep from the vacuole into the cytoplasm and go to build the body of the amoeba. Undissolved residues are thrown out anywhere in the body of the amoeba.

Dykhan ie amoeba vulgaris

The amoeba breathes oxygen dissolved in water, which penetrates into its cytoplasm through the entire surface of the body. With the participation of oxygen, complex food substances of the cytoplasm are decomposed into simpler ones. In this case, the energy necessary for the life of the body is released.

Isolation of harmful substances of vital activity and excess water of the common amoeba

Harmful substances are removed from the body of the amoeba through the surface of its body, as well as through a special bubble - the contractile vacuole. The water surrounding the amoeba constantly penetrates into the cytoplasm, liquefying it. The excess of this water harmful substances gradually fills the vacuole. From time to time the contents of the vacuole are thrown out.
So from environment amoeba receives food, water, oxygen. As a result of the life of the amoeba, they undergo changes. Digested food serves as material for building the body of the amoeba. The resulting substances harmful to the amoeba are removed to the outside. There is a metabolism of an amoeba ordinary. Not only the amoeba, but also all other living organisms cannot exist without metabolism both inside their body and with the environment.

Amoeba reproduction

The nutrition of the amoeba leads to the growth of its body. The grown amoeba begins to reproduce. Reproduction begins with a change in the nucleus. It is stretched, the transverse groove is divided into two halves, which diverge in different directions - two new nuclei are formed. The body of the amoeba is divided into two parts by a constriction. Each of them gets one nucleus. The cytoplasm between both parts is torn, and two new amoebas are formed. The contractile vacuole remains in one of them, while in the other it reappears. So, the amoeba reproduces by dividing in two. During the day, division can be repeated several times.

Common amoeba cyst

Amoeba feeding and reproduction occurs throughout the summer. In autumn, when cold weather sets in, the amoeba stops eating, its body becomes rounded, a dense protective shell is released on its surface - a cyst is formed. The same thing happens when the pond where the amoeba lives dries up. In the state of the cyst, the amoeba endures unfavorable living conditions. When favorable conditions occur, the amoeba leaves the cyst shell. She releases pseudopods, begins to feed and multiply. Cysts carried by the wind contribute to the settlement of amoebas.