Amoeba belongs to the phylum. Common amoeba: description, reproduction, habitat. Habitat and external structure of the common amoeba
The world is so unique that it is impossible to understand it if you do not at least study the basics and basics of existence. One of the unique objects of the animal world is the amoeba, which is studied in biology lessons at school.
Amoeba is a single-celled creature that can be found in polluted water bodies, as well as in the human body, but even to the naked eye it is not always noticeable. Seeing such a living creature is subject to a microscope.
Most people don’t even think that, thanks to this cute single-celled creature, people get intestinal infections, infections of the oropharynx, brain, and eyes.
Amoeba Proteus and its species
There are two types of pathogenic and non-pathogenic organisms.
The second type, non-pathogenic bacteria, includes more diversity than the first group:
There is also an oral amoeba, its name speaks for itself. It lives and reproduces in the human mouth and is a problem in most diseases of the oropharynx.
Shell amoeba
All amoebas are also divided into testate and testless. This is due to their shape. Ordinary amoebas change their shape, flowing from one leg to another, but testate ones do not.
What does an ordinary amoeba look like?
The common amoeba lives in polluted water and moves along the bottom of the reservoir. Outwardly, it looks like a slime toy thrown against a wall, only several thousand times reduced in size.
It does not have a skeleton, so it is constantly changing. Usually the structure and all functional features of amoebas are considered using the example of amoeba Proteus.
Life cycle
The cycle of life continues as long as conditions favorable for it exist. But if the conditions are not met, the single-celled creature falls into suspended animation - it sleeps and stops its activity, turning into a circle cyst.
But as soon as conditions become favorable, she wakes up again.
Structure
This single-celled organism has a completely simple structure. Apart from the nucleus and cytoplasm that fills its body, there is essentially nothing special.
There is a small vacuole that helps process microscopic single-celled particles (mostly algae) and thereby prolong the life of the amoeba.
There is also a contractile vacuole that helps it move. The outside of the body is surrounded by a membrane, a denser substance than the inside, to secure the body.
The inner part of the amoeba is the cytoplasm. It is more liquid and is called endoplasm, and closer to the edges it becomes thicker and is called ectoplasm.
Amoeba nutritional stages
As the amoeba moves through its environment, it encounters microscopic single-celled food products. They enter its body and become enveloped in a vacuole. Next, they are digested.
There may be several such vacuoles in the amoeba body. The process of splitting the single-celled organism into enzymes begins. Next, the split structures are absorbed into the amoeba, and then excretion occurs.
Reproduction
Amoeba does not need a partner to reproduce. She successfully does this herself when she is fully mature and ready to divide.
The core - its central dark part - changes in shape and resembles a small sausage. After some time, the sausage stretches, and its two end parts separate from each other, forming two dark drops - these are two new kernels.
After this, the amoeba also stretches its body in the middle and separates from each other. In 24 hours, its division can be repeated more than once. So, due to global warming and warmer weather, in many reservoirs the amoeba begins its colossal division, since nothing is stopping it.
There is no exchange of chromosomes, since there is no sexual process.
Breath
As a multicellular animal, amoeba can breathe. But she does not have special functioning respiratory organs. It absorbs oxygen throughout the body. And just like all living organisms, it emits carbon dioxide.
Selection
After absorbing food, this single-celled creature releases the products of its vital activity, that is, waste, into the external environment.
Organs of locomotion
It moves with the help of small outgrowths - pseudopods. These same outgrowths help in food consumption.
The amoeba constantly changes its shape, smoothly flowing into one or another of its “leg” outgrowths.
Habitat
Can live in any body of water, be it a river, lake or swamp. It can live even in an ordinary drop after rain or dew.
The most common habitat is polluted water bodies. These may be bodies of water in African and Asian countries. As well as reservoirs bordering landfills. Therefore, you cannot swim in such reservoirs, since you can introduce a whole bunch of microorganisms through your nose and mouth.
There is one of the most terrible diseases of our century associated with neuralgia and brain damage.
The cause is the killer amoeba Naegleria fowlera, it is also called a brain vacuum cleaner. It has no cure and is fatal. But such a bacterium is rarely found in our climate.
The meaning of amoeba vulgaris
On the other hand, if this microorganism is completely destroyed, the biological chain will be disrupted, and complete chaos will occur in the living world.
An example from real life: in China they decided that sparrows are carriers of infections, like our pigeons. There was a fee for catching sparrows. Thus, all the sparrows were destroyed. All kinds of insects began to multiply madly, destroying the crops. And after that, the Chinese authorities began purchasing sparrows from other countries to restore the eco-chain.
Conclusion
Amoeba is the simplest single-celled creature. But despite this, she has a lot inherent in her. It feeds, moves and reproduces. She breathes and feels. Its species are so diverse and amazing that one can only admire this miniature creature.
Amoeba proteus or common amoeba– lat. Amoeba proteus is a type of protozoan single-celled organism.
The structure of an ordinary amoeba
Amoebas have a fairly simple body structure. If you examine the amoeba under a microscope, you will notice 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 the common amoeba can safely be called a unicellular organism, consisting of protoplasm and a nucleus inside.
The body shape of the common amoeba constantly varies, hence the name “amoeba”, which is translated from Greek as “changeable”. The change in body shape occurs due to elongated pseudopods, which serve to move and capture food particles.
Habitat of the common amoeba
Proteus amoebas are widespread throughout the globe, most often found in fresh water bodies and aquariums, but can also be found in puddles and ditches. Common amoebas can survive even in the most unfavorable conditions. If living conditions worsen, for example, when a reservoir dries out, amoebas are 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, the amoeba begins to move and feed again. What makes amoebas and other single-celled protozoa one of the most survivable organisms on the planet.
Movement of the common amoeba
The movement of the amoeba is carried out due to the so-called pseudopods, which can appear anywhere in the amoeba’s body. 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 movement, an ordinary amoeba develops several processes (pseudopods) that differ in shape and size. The diversity in size and shape is due to the lack of a shell in Proteus amoeba.
Nutrition of the common amoeba
An ordinary amoeba feeds with the help of special extending processes or pseudopods, and thanks to which, as mentioned above, it moves. When food enters the protoplasm through the pseudopods, a drop of liquid called a digestive vacuole forms around the food particle. 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.
The common amoeba or amoeba proteus feeds on microscopic fungi, bacteria and algae.
Breathing amoeba proteus
In addition to nutrition, amoebas, like all living organisms, need oxygen. If you move the amoeba into boiled water, you will notice that after some time the ordinary amoeba dies due to lack of oxygen. From this we can conclude that amoebas absorb oxygen from water and release carbon dioxide.
Amoeba respiration occurs over the entire surface of the body, due to a contractile vesicle or vacuole appearing inside the body. Which periodically increases, decreases, or disappears altogether. 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 expelled.
Reproduction of the common amoeba
Reproduction occurs due to cell division. During division, the ordinary amoeba stops moving, and the contractile vacuole also disappears. During reproduction, the amoeba nucleus first lengthens slightly and then divides in half. Next, the protoplasm divides. As a result, two daughter amoebas appear, which in a short period of time grow to the size of an adult amoeba.
Amoeba is a representative of single-celled animals capable of actively moving 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 protozoa have this name, their structure is quite complex. After all, one microscopic cell is capable of performing the functions of an entire organism. Amoeba is another proof that an organism up to 0.5 mm in size is capable of breathing, moving, reproducing, growing and developing.
Protozoan movement
Single-celled organisms move with the help of special organelles. In ciliates they are called cilia. Just imagine: on the surface of a cell, up to 0.3 mm in size, there are about 15 thousand of these organelles. Each of them makes pendulum-like movements.
Euglena has a flagellum. Unlike cilia, it makes helical movements. But what these organelles have in common is that they are permanent outgrowths of the cell.
The movement of the amoeba is due to the presence of pseudopods. They are also called pseudopodia. These are unstable cellular structures. Due to the elasticity of the membrane, they can form anywhere. First, the cytoplasm moves outward and a protrusion is formed. Then the reverse process follows, the pseudopods are directed into the cell. As a result, the amoeba moves slowly. The presence of pseudopods is a distinctive characteristic feature of this representative of the subkingdom Unicellular.
Amoeba proteus
Amoeba structure
All protozoan cells are eukaryotic - they contain a nucleus. The organs of the amoeba, or rather its organelles, are capable of carrying out all life processes. The pseudopods are involved not only in movement, but also provide the process of feeding the amoeba. With their help, a single-celled animal embraces a food particle, which is surrounded by a membrane and ends up inside the cell. This is the process of formation of digestive vacuoles, in which the breakdown of substances occurs. This method of absorption of solid particles is called phagocytosis. Undigested food remains are 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 with the help of 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 lower one. regulate this process by removing some metabolic products along with water.
Amoebas are characterized by asexual reproduction by two. This is the most primitive of all known methods, but it ensures the accurate preservation and transmission of hereditary information. In this case, first the organelles occur, and then the separation of the cell membrane occurs.
This simplest organism is able to respond to environmental factors: light, temperature, changes in the chemical composition of the reservoir.
Single-celled organisms tolerate unfavorable conditions in the form of cysts. Such a cell stops moving, its water content decreases, and the pseudopods are retracted. And it itself is covered with a very dense shell. This is a cyst. When favorable conditions occur, the amoebas emerge from the cysts and proceed to normal life processes.
Dysenteric amoeba
Many species of these protozoa also play a positive role in nature. Amoebas are a source of food for many animals, namely fry of fish, worms, mollusks, and small crustaceans. They clean fresh water bodies of bacteria and rotting algae and are an indicator of the cleanliness of the environment. took part in the formation of limestone and chalk deposits.
Amoeba vulgaris is a type of protozoan eukaryotic creature, a typical representative of the genus Amoeba.
Taxonomy. The species of common amoeba belongs to the kingdom - Animals, phylum - Amoebozoa. Amoebas are united in the class Lobosa and order - Amoebida, family - Amoebidae, genus - Amoeba.
Characteristic processes. Although amoebas are simple, single-celled creatures that do not have any organs, they possess all vital processes. They are able to move, get food, reproduce, absorb oxygen, and remove metabolic products.
Structure
The common amoeba is a unicellular animal, the body shape is uncertain and changes due to the constant movement of the pseudopods. The dimensions do not exceed half a millimeter, and the outside of its body is surrounded by a membrane - plasmalem. Inside there is cytoplasm with structural elements. Cytoplasm is a heterogeneous mass, where two parts are distinguished:
- External - ectoplasm;
- internal, with a granular structure - endoplasm, where all intracellular organelles are concentrated.
The common amoeba has a large nucleus, which is located approximately in the center of the animal's body. It has nuclear sap, chromatin and is covered with a membrane with numerous pores.
Under a microscope it can be seen that the common amoeba forms pseudopodia into which the cytoplasm of the animal is poured. At the moment of pseudopodia formation, endoplasm rushes into it, which in the peripheral areas becomes denser and turns into ectoplasm. At this time, on the opposite part of the body, ectoplasm partially transforms into endoplasm. Thus, the formation of pseudopodia is based on the reversible phenomenon of the transformation of ectoplasm into endoplasm and vice versa.
Breath
The amoeba receives O 2 from water, which diffuses into the internal cavity through the outer integument. The whole body participates in the respiratory act. Oxygen entering the cytoplasm is necessary to break down nutrients into simple components that Amoeba proteus can digest, and also to obtain energy.
Habitat
Inhabits fresh water in ditches, small ponds and swamps. Can also live in aquariums. Amoeba vulgaris culture can be easily propagated in the laboratory. It is one of the large free-living amoebas, reaching 50 microns in diameter and visible to the naked eye.
Nutrition
The common amoeba moves with the help of pseudopods. She covers one centimeter in five minutes. While moving, amoebas encounter various small objects: unicellular algae, bacteria, small protozoa, etc. If the object is small enough, the amoeba flows around it from all sides and it, along with a small amount of liquid, ends up inside the cytoplasm of the protozoa.
Amoeba vulgaris nutritional diagram The process of absorption of solid food by the common amoeba is called phagocytosis. Thus, digestive vacuoles are formed in the endoplasm, into which digestive enzymes enter from the endoplasm and intracellular digestion occurs. Liquid digestion products penetrate the endoplasm, a vacuole with undigested food remains approaches the surface of the body and is thrown out.
In addition to digestive vacuoles, the body of amoebas also contains a so-called contractile, or pulsating, vacuole. This is a bubble of watery liquid that periodically grows, and when it reaches a certain volume, it bursts, emptying its contents out.
The main function of the contractile vacuole is to regulate osmotic pressure inside the protozoan body. Due to the fact that the concentration of substances in the cytoplasm of the amoeba is higher than in fresh water, a difference in osmotic pressure is created inside and outside the body of the protozoa. Therefore, fresh water penetrates the amoeba’s body, but its amount remains within the physiological norm, since the pulsating vacuole “pumps out” excess water from the body. This function of vacuoles is confirmed by their presence only in freshwater protozoa. In marine animals it is either absent or reduced very rarely.
In addition to the osmoregulatory function, the contractile vacuole partially performs an excretory function, removing metabolic products along with water into the environment. However, the main function of excretion is carried out directly through the outer membrane. The contractile vacuole probably plays a certain role in the process of respiration, since water penetrating into the cytoplasm as a result of osmosis carries dissolved oxygen.
Reproduction
Amoebas are characterized by asexual reproduction, carried out by dividing in two. This process begins with mitotic division of the nucleus, which lengthens longitudinally and is separated by a septum into 2 independent organelles. They move away and form new nuclei. The cytoplasm with the membrane is divided by a constriction. The contractile vacuole does not divide, but enters one of the newly formed amoebae; in the second, the vacuole forms independently. Amoebas reproduce quite quickly; the division process can occur several times during the day.
In the summer, amoebas grow and divide, but with the arrival of autumn cold, due to the drying up of water bodies, it is difficult to find nutrients. Therefore, the amoeba turns into a cyst, finding itself in critical conditions and becomes covered with a durable double protein shell. At the same time, cysts easily spread with the wind.
Meaning in nature and human life
Amoeba proteus is an important component of ecological systems. It regulates the number of bacterial organisms in lakes and ponds. Purifies the aquatic environment from excessive pollution. It is also an important component of food chains. Single-celled organisms are food for small fish and insects.
Scientists use the amoeba as a laboratory animal, conducting many studies on it. Amoeba not only cleans bodies of water, but once it settles in the human body, it absorbs destroyed particles of epithelial tissue of the digestive tract.
The subkingdom Unicellular, or Protozoa, includes animals whose body consists of one cell. The sizes of protozoa are on average 0.1-0.5 mm. There are even smaller individuals - about 0.01 mm. There are also quite large organisms, several millimeters and even centimeters long.
live simplest single-celled animals mainly in a liquid environment - in sea and fresh water, moist soil, and in other organisms. Externally they are very diverse. Some resemble shapeless gelatinous lumps (for example, amoebas), others have a geometrically regular shape (for example, rays).
There are about 30 thousand species of protozoa.
The structure of the ciliate slipper and amoeba
The structure of green euglena
Table of characteristics of the simplest unicellular animals
|
Signs of protozoa |
Common amoeba (Rhizopod class) |
Euglena green (class Flagellates) |
Infusoria tu-felka (Infusoria class) |
|
Structure |
Consists of cytoplasm, nucleus, contractile vacuole, pseudopod, digestive vacuole (see figure) |
Consists of a shell, nucleus, flagellum, ocellus, contractile vacuole, nutrients, chloroplasts (see figure) |
Consists of a membrane, small and large nucleus, contractile and digestive vacuole, mouth, powder, cilia (see Fig.) |
|
Movement |
“Overflowing” with the help of pseudopods |
Locomotion using a flagellum |
Moving with the help of eyelashes |
|
The food can be bacteria or microscopic algae. The amoeba captures food by extending its pseudopods anywhere on the body. They envelop the prey and, together with a small amount of water, immerse it in the cytoplasm. This is how a digestive vacuole is formed - phagocytosis, capture of liquid droplets - pinocytosis. From the digestive vacuole, soluble digestion products enter the cytoplasm, and undigested residues are excreted from the body in any part of the cell. |
Autotrophic (photosynthesis) or heterotrophic (phagocytosis and pinocytosis) |
They feed on various microorganisms, mainly bacteria. By moving the cilia located along the mouth cavity, prey is driven into it. Together with water, it enters the cell mouth, then into the pharynx. A digestive vacuole is formed, and undigested residues are thrown out through the powder. |
|
|
Reproduction |
Amoeba reproduces by division. In this case, the nucleus splits in two. The new nuclei formed diverge to the sides, and a transverse constriction appears between them, dividing the amoeba into two daughter cells that live independently. After some time, young amoebas also begin to divide. The water temperature is favorable for reproduction around +20 °C. |
Reproduction of organisms of this species of euglena is asexual - by dividing the cell in half, in contrast to the slipper ciliates, which is also characterized by a sexual process. |
Ciliates reproduce asexually - by transverse division, like amoebas. The small nucleus divides in two first, then the large one. At the same time, a transverse constriction appears. Over time, it divides the ciliate into two young (daughter) cells. They grow and, with good nutrition and optimal temperature, become adults within the next day and can divide again. Ciliates are also characterized by the sexual process in the form conjugation(fusion of two cells and exchange of genetic information) |
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A source of information: Biology in tables and diagrams./ Edition 2, - St. Petersburg: 2004.
