The structure of sarcodes by example
amoeba proteus - Amoeba proteus

Body shape, differentiation of protoplasm and amoeba movement; vacuoles and nucleus

Work 1. Body shape, differentiation of protoplasm and amoeba movement. The name "naked amoeba" these animals received because of their lack of a shell; they also don't have a shell. Living protoplasm is constantly slowly flowing in one direction or the other, as a result of which the shape of the body of an individual is constantly changing.

In the amoeba one can clearly see the layer-by-layer differentiation of the cytoplasm. Outer layer, ectoplasm, vitreous: transparent, structureless, homogeneous in its internal structure; it is a viscous compacted layer of protoplasm; it covers the entire body of the amoeba like a cover, performing, in particular, the function of protection from external influences (Fig. 4). The inner layer, endoplasm, is darker, liquid, with a granular structure; the endoplasm is in a state of constant fluidity. Two layers of protoplasm are two states of the same colloidal substance, passing from one to another; there is no boundary structure between the layers.

On one of the parts of the body of the amoeba, protoplasm flows from the center to the periphery, forming a pseudopod, or pseudopodia; simultaneously, in the opposite area, the protoplasm flows in the opposite direction, towards the central part of the body, and the other pseudopodia is drawn in. So all the protoplasm flows in a certain direction, and the amoeba slowly moves from one place to another. Such movement of the animal with the help of temporary formations, specific for sarcodes, was called amoeboid. At the anterior end of the pseudopodia, the endoplasm, reaching the surface of the body, turns into ectoplasm; when the pseudopodia is retracted, the ectoplasm inside the body passes into the endoplasm. In the process

formation of pseudopodia, the layer-by-layer differentiation of protoplasm described above is especially clear.

The number of pseudopodia in an amoeba depends on the species to which it belongs (Fig. 4). At Amoeba limax- a single pseudopodium on the side of the body in the direction of movement. At A.proteus there are several, up to ten. The shape of the pseudopodia is different. However, both the number and shape of pseudopodia depend to a greater extent on external conditions.

In terms of the function performed, the pseudopodia is similar to the organs of movement of multicellular animals, but in structure it differs significantly from them, since it is formed not by many cells, but only by a section of a unicellular body; this kind of adaptation to the performance of functions in protozoa is called, in contrast to organs, organelles.

Rice. 4. Free-living amoeba. BUT- building diagram Amoeba proteus; B- Amoeba Umax; AT- A. radiosa, with a form of pseudopodia characteristic of each species:
1 - pseudopodia; 2 - ectoplasm; 3 - endoplasm; 4 - food vacuole; 5 - contractile vacuole; 6 - nucleus

Progress. Sarcodidae are studied mainly on living material. The absence of live animals is only partially compensated by the use of ready-made micropreparations.

Make a temporary preparation from a drop of culture; cover glass to provide wax "legs". Find an amoeba under a microscope at low magnification; observe it calmly and for a long time in a slightly shaded field at high magnification, avoiding shocks and shaking of the specimen. When observing an amoeba in a living form, consider: a) an indefinite body shape; draw outlines

bodies in four or five successive stages of changing the shape of the body; b) different layers of protoplasm; indicate them in the figure and note the function of ectoplasm; c) trace the process of formation (or outflow) of pseudopodia and its disappearance (retraction); draw in the figure the number and shape of pseudopodia, approximately corresponding to the observations, and note their function.

In the absence of amoebas, the task can be completed on the artella.

Work 2. Vacuoles and nucleus. The amoeba feeds on small algae, bacteria, etc., which it captures with pseudopodia. Moving from place to place, it encounters food objects and flows around them until it is completely surrounded. Food with a small amount of water is inside the protoplasm. This is how food, or digestive, vacuole is formed; enzymes flow here from the protoplasm surrounding the vacuole, under the influence of which digestion is carried out. A food vacuole is formed in any part of the body of an amoeba that has come into contact with food. Digested food in dissolved form directly passes into the protoplasm and is assimilated. Indigestible residues are thrown out through the surface of the body in any place where the food vacuole approaches, after which it disappears, since it does not have its own wall. Therefore, eating and removing non-digestible residues, i.e. defecation, not confined to a specific area of ​​the body.

In terms of its function, the digestive organelle - the food vacuole - is similar to the digestive system of multicellular animals.

Contractile, or pulsating, i.e. periodically appearing and disappearing, the vacuole is represented in the amoeba by a bubble under the ectoplasm (see Fig. 4). As it fills, the bubble slowly increases in size, when it reaches the limit value, it bursts, and the contents pour out through the ectoplasm. The rate of vacuole pulsation depends on external conditions (temperature, etc.). At room temperature, it takes a few minutes to fill.

The contractile, or pulsating, vacuole in the amoeba does not have a permanent location. Since the concentration of salts and, accordingly, the osmotic pressure in the protoplasm is higher than in fresh water, water constantly penetrates into the body of the amoeba from the outside; excess of it is brought out (pumped out)

by the action of a pulsating vacuole, which thereby fulfills the role osmoregulatory apparatus.

In the contractile vacuole, along with water, the end products of the chemical decomposition of proteins and carbohydrates, i.e., dissimilation products, come from the protoplasm and are brought out. The contractile vacuole therefore also serves as an organelle of excretion, like the kidneys, organs of higher animals with the same function. With water through the contractile vacuole, in particular, carbon dioxide dissolved in it is removed; this is how breathing is partially carried out, mainly flowing through the entire surface of the body.

Progress. 1. Continuing to observe the amoeba at high magnification of the microscope: a) find food vacuoles and excretory vacuole; mark them in the picture; b) follow the filling and disappearance of the vacuole. 2. In a living amoeba, the nucleus is difficult to detect. Examine it on a special pre-prepared micropreparation, where the amoeba are killed (fixed) and stained; draw the core into a general drawing.

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 dimensions (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 release carbon dioxide into the external environment.

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

Food

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 actively multiply.

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 develops, negative manifestations increase in the form of fever, chills, vomiting, and 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: an increase in 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.

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.

Amoeba habitat

The common amoeba is found in the mud at the bottom of polluted water ponds. 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 within 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 protozoa capable of forming pseudopods are classified as rhizopods. They got this name for the outward resemblance of pseudopods to plant roots.

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 are formed that 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 with harmful substances gradually fills the vacuole. From time to time the contents of the vacuole are thrown out.
So, from the environment, food, water, oxygen enter the body of the amoeba. 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.

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 greatest species diversity is 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 the ancient Greek god Proteus).

There are more than 100 types of proteas, among them 6 species are described, found in different parts of the 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, are sensitive to chemical stimuli and mechanical stress.

When unfavorable living conditions occur, the protea form 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 food

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 rhizomes 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 characteristic of types is determined by the shape of the cell and the type of branching of 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 secreted 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 protozoa.

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 the circulatory system and switch to nutrition with red blood cells.

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.