The outer membrane, and one or more nuclei. The light and dense outer layer is called ectoplasm, and the inner layer is called endoplasm. The amoeba endoplasm contains cellular organelles: contractile and digestive vacuoles, mitochondria, ribosomes, elements of the Golgi apparatus, endoplasmic reticulum, supporting and contractile fibers.

Breathing and excretion

Cellular respiration of the amoeba occurs with the participation of oxygen, when it becomes less than in the external environment, new molecules enter the cell. The harmful substances and carbon dioxide accumulated as a result of vital activity are removed to the outside. Liquid enters the body of the amoeba through thin tubular channels, this process is called. The contractile vacuoles are involved in pumping out excess water. Gradually filling, they contract sharply and are pushed out about once every 5-10 minutes. Moreover, vacuoles can form in any part of the body. The digestive vacuole approaches the cell membrane and opens outward, as a result of which undigested residues are released into the external environment.

Nutrition

The amoeba feeds on unicellular algae, bacteria and smaller unicellular organisms, bumping into them, it flows around them and includes them in the cytoplasm, forming a digestive vacuole. It receives enzymes that break down proteins, lipids and carbohydrates, so intracellular digestion occurs. Once digested, food enters the cytoplasm.

Reproduction

Amoebas reproduce asexually, by division. This process does not differ from cell division, which occurs during the growth of a multicellular organism. The only difference is that daughter cells become independent organisms.

At first, the nucleus is doubled so that each daughter cell has its own copy of hereditary information. The core is first pulled out, then lengthened and pulled in the middle. Forming a transverse groove, it divides into two halves, which form two nuclei. They diverge in different directions, and the body of the amoeba is divided into two parts by a constriction, forming two new unicellular organisms. Each of them gets one nucleus, and the formation of missing organelles also occurs. The division can be repeated several times in one day.

Cyst formation

Single-celled organisms are sensitive to changes in the external environment; in unfavorable conditions, a large amount of water is released from the cytoplasm on the surface of the amoeba's body. The secreting water and cytoplasmic substances form a dense membrane. This process can occur in the cold season, when the reservoir dries up or in other conditions unfavorable for the amoeba. The body goes into a dormant state, forming a cyst, in which all life processes are suspended. Cysts can be carried by the wind, which contributes to the dispersal of amoebas. When favorable conditions occur, the amoeba leaves the cyst membrane and goes into an active state.

Sources:

• Biouroki, Amoeba vulgaris

Reproduction is a natural property of living things. It can be sexual and asexual - i.e. with the participation of only one individual, in the absence of an individual of the opposite sex. The latter is found in certain species of plants and fungi, as well as in the simplest organisms.

Instructions

Asexual reproduction occurs without the exchange of genetic information between two individuals of different sexes. It is typical for the simplest unicellular organisms - amoebas, ciliates-shoes. They do not have variability; for millennia, daughter individuals completely copy their parents.

One of the methods of asexual reproduction is division, when two daughter ones are formed from one individual (for example, amoeba). In this case, the nucleus of the organism first begins to divide, and then the cytoplasm splits in two. This method is also common among bacteria.

The starfish reproduces in a fragmented way: the "mother" organism is divided into parts, and each of them becomes a full-fledged new starfish.

Another way is reproduction by spores. Here we are talking about multicellular organisms - fungi and plants. With asexual reproduction, only one plant is involved in this process. It forms spores or separates viable areas of the vegetative body, and from them daughter individuals are formed under favorable circumstances.

Vegetative propagation in plants occurs with the help of vegetative organs - leaves, roots, etc. The violet, for example, is propagated by the leaves, and the raspberry by the roots. This phenomenon is especially common among wild plants. Vegetative reproduction is natural and artificial when it is carried out by humans.

Often in natural conditions, certain types of plants reproduce with the same organs: tulips, lilies, daffodils, onions and garlic - with bulbs; dahlias, Jerusalem artichoke, potatoes - tubers; - creeping shoots (mustache); ivan tea, horsetail, yarrow - rhizomes.

The advantage of artificial vegetative reproduction is that it allows you to maintain genetic purity in breeding, because the daughter plant takes on all the qualities of the parent. And the minus is in a decrease in resistance to diseases and pests, which is observed after several years of asexual reproduction.

In agriculture and horticulture, methods of artificial vegetative propagation are used by dividing bushes, layering, cuttings and grafting.

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One of the foods that can get rid of the oral cavity is parsley. This plant is also excellent at neutralizing the smell of tobacco. Less potent in properties are cardamom, coriander, wormwood, rosemary and eucalyptus. For the greatest effect, the herbs need as long as possible or for the gums.

To create an environment in the oral cavity that is unfavorable for the growth of bacteria, eat more berries, watermelons, citrus fruits and other fruits and vegetables rich in vitamin C. Regular consumption of such food is again beneficial. Do not replace natural vitamin C with an artificial supplement, as it can cause digestive upset.

Do not forget about green tea, which successfully removes bacteria from the surface of the gums and teeth. This drink is rich in flavonoids, which not only relieve the oral cavity from unpleasant odor, but also whiten teeth and improve metabolism.

You should pay attention to fermented milk products. Like yoghurts, they reduce the level of hydrogen sulfide in the mouth and freshen the breath. Also, the substances contained in fermented milk products prevent fermentation bacteria from multiplying and the oral cavity is unsuitable for their life.

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Habitat of the common amoeba

The common amoeba is found in silt at the bottom of polluted 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 examine the details of the structure of the amoeba 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 vesicular nucleus enclosed inside it. 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 in this place on its body. It increases, becomes an outgrowth of the body - a pseudopod, cytoplasm flows into it, and the amoeba moves in this way. Amoeba and other protozoa capable of forming pseudopods are referred to the group of rhizopods. They received this name for the external resemblance of pseudopods to plant roots.

Common amoeba nutrition

In an amoeba, several pseudopods can form at the same time, and then they surround food - bacteria, algae, and other protozoa. Digestive juice is secreted from the cytoplasm surrounding the prey. A bubble is formed - a digestive vacuole.
Digestive juice dissolves some of the substances that make up the food, and digests them. As a result of digestion, nutrients are formed, 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 no common amoeba

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. At the same time, energy is released, which is necessary for the vital activity of the organism.

The release of harmful substances of vital activity and excess water of the common amoeba

Harmful substances are removed from the amoeba's body through the surface of its body, as well as through a special vesicle - the contractile vacuole. The water surrounding the amoeba constantly penetrates the cytoplasm, diluting it. An excess of this water with harmful substances gradually fills the vacuole. From time to time, the contents of the vacuole are thrown out.
So, food, water, oxygen enter the amoeba organism from the environment. As a result of the vital activity of the amoeba, they undergo changes. Digested food serves as the material for building the body of the amoeba. The resulting substances harmful to the amoeba are removed to the outside. The metabolism of the common amoeba takes place. Not only amoeba, but all other living organisms cannot exist without metabolism both inside their body and with the environment.

Reproduction of the common amoeba

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

Common amoeba cyst

Amoeba feeding and reproduction occurs throughout the summer. In autumn, with the onset of cold weather, the amoeba stops eating, its body becomes rounded, a dense protective shell stands out on its surface - a cyst is formed. The same happens when the pond where the amoebas live dries up. In a cyst state, the amoeba endures unfavorable living conditions for it. When favorable conditions occur, the amoeba leaves the cyst membrane. It releases pseudopods, begins to feed and reproduce. Cysts carried by the wind facilitate the dispersal of amoebas.

Amoebae, shell amoebae, foraminifera

Movement organelles such as lobopodia or rhizopodia are characteristic of rhizopodia. A number of species form an organic or mineral shell. The main method of reproduction is asexual by mitotic cell division in two. In some species, there is an alternation of asexual and sexual reproduction.

The following groups belong to the class Rootlegs: 1) Amoebas, 2) Shell amoebas, 3) Foraminifera.

Amoebina squad

rice. one.
1 - nucleus, 2 - ectoplasm, 3 - endoplasm,
4 - pseudopod, 5 - digestive
vacuole, 6 - contractile vacuole.

Amoeba proteus (Fig. 1) lives in fresh water bodies. Reaches a length of 0.5 mm. It has long pseudopodia, one nucleus, a shaped cell mouth and no powder.

rice. 2.
1 - pseudopodia of amoeba,
2 - food particles.

It feeds on bacteria, algae, particles of organic matter, etc. The process of capturing solid food particles occurs with the help of pseudopodia and is called phagocytosis (Fig. 2). A phagocytic vacuole is formed around the captured food particle, digestive enzymes enter it, after which it turns into a digestive vacuole. The process of absorption of liquid food masses is called pinocytosis. In this case, solutions of organic substances enter the amoeba through thin channels that are formed in the ectoplasm by invagination. A pinocytic vacuole is formed, it is detached from the canal, enzymes enter it, and this pinocytic vacuole also becomes a digestive vacuole.

In addition to the digestive vacuoles, there is a contractile vacuole that removes excess water from the amoeba's body.

Reproduces by dividing the mother cell into two daughter cells (Fig. 3). The division is based on mitosis.

rice. 3.

Under unfavorable conditions, the amoeba is encysted. Cysts are resistant to drying out, low and high temperatures, water currents and air currents are transported over long distances. Once in favorable conditions, cysts open, and amoeba emerge from them.

The dysentery amoeba (Entamoeba histolytica) lives in the human colon. It can cause a disease - amebiasis. In the life cycle of a dysentery amoeba, the following stages are distinguished: cyst, small vegetative form, large vegetative form, tissue form. The invasive (infectious) stage is the cyst. Cyst enters the human body orally with food or water. In the human intestine, amoebae emerge from the cysts, which are small in size (7-15 microns), feed mainly on bacteria, multiply and do not cause disease in humans. This is a small vegetative form (Fig. 4). When it enters the lower parts of the large intestine, it encysts. Cysts excreted with feces can get into water or soil, then into food. The phenomenon in which the dysentery amoeba lives in the intestines without harming the host is called cyst carrier.

rice. 4.
A - small vegetative form,
B - large vegetative form
(erythrophage): 1 - nucleus,
2 - phagocytosed erythrocytes.

Laboratory diagnostics of amebiasis - examination of fecal smears under a microscope. In the acute period of the disease, large vegetative forms (erythrophages) are found in the smear (Fig. 4), in the case of a chronic form or cyst carrier - cysts.

Flies and cockroaches are mechanical carriers of cysts of dysentery amoebae.

Intestinal amoeba (Entamoeba coli) lives in the lumen of the large intestine. The intestinal amoeba feeds on bacteria, plant and animal food residues, without causing any harm to the owner. He never swallows red blood cells, even if they are in the intestines in large quantities. It forms cysts in the lower part of the large intestine. Unlike the four-core cysts of the dysentery amoeba, the intestinal amoeba cysts have eight or two nuclei.

rice. 5.
A - arcella (Arcella sp.),
B - difflugia (Difflugia sp.).

Order Conch amoeba (Testacea)

Representatives of this order are freshwater benthic organisms; some species live in the soil. They have a shell, the size of which varies from 50 to 150 µm (Fig. 5). The shell can be: a) organic ("chitinoid"), b) from silicon plates, c) inlaid with grains of sand. They multiply by dividing the cell in two. In this case, one daughter cell remains in the mother's shell, the other builds a new one for itself. They lead only a free lifestyle.

Order of Foraminifera (Foraminifera)

rice. 6.
A - planktonic foraminifera globigerin
(Globigerina sp.), B - multi-chamber calcareous
Elfidium shell (Elphidium sp.).

Foraminifers live in sea water bodies, are part of the benthos, with the exception of the families Globigerina (Fig. 6A) and Globorotalids, which lead a planktonic lifestyle. Foraminifera have shells, the sizes of which vary from 20 microns to 5-6 cm, in foraminifera species - up to 16 cm (nummulites). Shells are: a) calcareous (the most common), b) organic from pseudochitin, c) organic, inlaid with grains of sand. Calcareous shells can be single-chambered or multi-chambered with a mouth (Fig. 6B). The partitions between the chambers are pierced with holes. Very long and thin rhizopodia emerge both through the shell mouth and through the numerous pores that penetrate its walls. In some species, the shell wall has no pores. The number of cores is from one to many. They reproduce asexually and sexually, which alternate with each other. Sexual reproduction is of the isogamous type.

Foraminifera play an important role in the formation of sedimentary rocks (chalk, nummulite limestones, fusulin limestones, etc.). Foraminifera have been known in the fossil state since the Cambrian period. Each geological period is characterized by its own mass species of foraminifera. These views are guiding forms for determining the age of geologic strata.

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

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

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

1. naked;
2. conchial;
3. foraminifera.

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

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

Radiolarians with a skeleton are sometimes referred to marine amoebae, although according to the classification they belong to another subclass of sarcode.

For medical practice, of interest are naked (ordinary) amoebas, 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 specific 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 species of Proteus, among them 6 species are described that are found in different parts of the human body:

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

All proteas consist of one cell, the body of which is covered with a thin cytoplasmic membrane. The membrane protects a dense transparent ectoplasm, behind which 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.

Proteus breathe with the whole 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 varies from 10 microns to 3 mm.

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

When unfavorable living conditions occur, the proteas form a cyst: the shape of the amoeba is rounded, and a protective shell is formed on the surface. The processes inside the cell slow down until the onset of favorable times.

Features allows the animal body to form cytoplasmic outgrowths, which have various names:

• pseudopodia;
• rhizomes;
• pseudopods.

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

Moving and feeding

Roots provide movement of the unicellular amoeba and capture of the detected food. Regardless of the habitat, the amoeba-like movement consists in the protrusion of the root in a certain direction and the subsequent overflow of the cytoplasm into the cell. The pseudopodia then re-form elsewhere. There is a constant imperceptible overflow of the body in search of food. This method of movement 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 on by phagocytosis. Food for this heterotroph can be:

• bacteria;
• unicellular algae;
• small protozoa.

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

Digestive juice is released from the cytoplasm into the formed area - a digestive vacuole is formed. After the absorption of nutrients, undigested food debris is 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 amoeba's ability to move independently allows it to regulate the number of bacteria and pathogens that it feeds on. Biocenoses of sewage silt deposits, peat and boggy soils, fresh and sea waters are impossible without the participation of protozoa.

Even the 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 feeding on erythrocytes.

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

One of the representatives of unicellular animals (protozoa) that have the ability to move independently using the so-called "pseudopods" is called Amoeba vulgaris or Proteus. It belongs to the type of rhizopods because of its fickle appearance, which form, change and disappear pseudopods.

It has the form of a small gelatinous lump, barely distinguishable by the naked eye, that has no color, about 0.5 mm in size, the main characteristic of which is the variability of shape, hence the name - "amoeba", which means "changeable".

It is impossible to examine in detail the structure of the cell of an ordinary amoeba without a microscope.

Any body of water with fresh stagnant water is an ideal habitat for an amoeba, especially ponds with a large content of rotting plants and swamps, which are rich in bacteria.

At the same time, it will be able to survive in soil moisture, in a drop of dew, in water inside a person, and even in an ordinary rotting leaf of a tree, amoeba, amoeba can be noticed, in other words, they directly depend on water.

The presence of a large number of microorganisms and unicellular algae is a clear sign of the presence of Proteus in the water, since it feeds on them.

When negative conditions for existence come (the onset of autumn, the drying up of the reservoir), the protozoan stops feeding. Taking the shape of a ball, a special shell appears on the body of a single-celled animal - a cyst. The organism can stay inside this film for a long time.

In the state of a cyst, the cell waits out drought or cold (while the protozoan does not freeze and does not dry out), until the environmental conditions change or the cyst is transferred by the wind to a more favorable place, the life of the amoeba cell stops.

This is how the common amoeba protects itself from adverse conditions, when the habitat becomes suitable for life, the proteus leaves the shell and continues to lead a normal life.

There is the ability to regenerate, when the body is damaged, it can complete the destroyed place, the main condition for this process is the integrity of the nucleus.

The structure and metabolism of the simplest

To examine the internal structure of a single-celled organism, a microscope is needed. It will allow you to see that the structure of the body of an amoeba is a whole organism that is able to independently perform all the functions necessary for survival.

Its body is covered with a thin film, which is called, and contains a semi-liquid cytoplasm. The inner layer of the cytoplasm is more liquid and less transparent than the outer one. It contains the nucleus and vacuoles.

The digestive vacuole is used for digestion and disposal of undigested residues. begins to be carried out from contact with food, a "food cup" appears on the surface of the cell body. When the walls of the "cup" are closed, digestive juice enters there, so a digestive vacuole appears.

The resulting nutrients from digestion are used to build the body of the proteus.

The digestion process can take from 12 hours to 5 days. This type of nutrition is called phagocytosis. In order to breathe, the protozoan absorbs water over the entire surface of the body, from which it then releases oxygen.

To perform the function of secreting excess water, as well as regulating pressure inside the body, the amoeba has a contractile vacuole, through which waste products can sometimes be released. This is how the amoeba breathes, the process is called pinocytosis.

Movement and response to stimuli

For movement, the common amoeba uses a pseudopod, their other name is pseudopod or rhizopod (due to the similarity with plant roots). They can form anywhere on the surface of the body. When the cytoplasm overflows to the edge of the cell, a bulge appears on the surface of the proteus, and a false leg is formed.

In several places, the leg attaches to the surface, and the remaining cytoplasm gradually flows into it.

Thus, movement occurs at a speed of approximately 0.2 mm per minute. The cell can form several pseudopodia. The body reacts to various stimuli, i.e. has the ability to feel.

Reproduction

While feeding, the cell grows, increases, the process for the sake of which all creatures live - reproduction begins.

Reproduction of the common amoeba, the simplest process known to science, occurs asexually, and implies division into parts. Reproduction begins at the stage when the core of the amoeba begins to stretch and narrow in the middle until it splits in two. At this time, the body of the cell itself is also divided. Each of these parts has a core.

In the end, the cytoplasm between the two parts of the cell ruptures, and the newly formed cellular organism is separated from the maternal organism, in which a contractile vacuole remains. The stage of division is also due to the fact that the proteus stops eating, digestion stops, the body takes on a rounded appearance.

Thus, Proteus multiplies. The cell can multiply several times during the day.

Significance in nature

As an important element of any ecosystem, the common amoeba regulates the number of bacteria and microorganisms in its habitat. Thus, maintaining the cleanliness of reservoirs.

Thus, being part of the food chain, it feeds on small fish, crustaceans and insects for which it is food.