Amoeba ordinary outwardly represents a cell, is directly related to the type of protozoa, to the class of rhizopods, or they are also called Sarkodovye. They have pseudopods, which are the organs with which they move and capture food. There is no dense shell in the cell, in connection with which the amoeba can easily change its shape. The outer covering is a very thin cytoplasmic membrane.
Amoeba ordinary structure.
Amoeba is very simple. One of the simplest living beings. Has no skeleton. Amoeba ordinary lives at the bottom of various reservoirs, in silt. There is one thing: in fresh water only: a pond, a ditch, etc. If you look at it, it is noticeable that this gray transparent lump does not have a permanent shape. The name of this creature is translated as "changeable." On the body of the cell, pseudopods are constantly formed, due to the fact that the cytoplasm flows back and forth. The size of the lump can be at least 0.2 millimeters and at most 0.7 millimeters. Organelles - pseudopods contribute to the movement of this tiny creature. The movement is very slow, it resembles the flow of thick mucus. In the process of movement, the amoeba encounters various single-celled organisms, such as algae, bacteria. It flows around them and, as it were, sucks in its own cytoplasm, and a digestive vacuole is formed.
Amoeba ordinary cytoplasm secretes specific enzymes that digest food. There is a process of intracellular digestion. Digested foods in liquid form enter the cytoplasm itself, and undigested food residues are discarded. This way of capturing food is called phagocytosis. In the body of the amoeba there are thin channels through which fluid enters the cell body. This process is called pinocytosis. There is one vacuole available, throwing excess liquid products out. It's called Get Rid of Excess Every Five Minutes. The endoplasm contains a nucleus. Reproduction occurs as follows: the cell divides in half, that is, asexually.
How an amoeba fences itself off from adverse external influences.
Amoeba ordinary and dysenteric amoeba are Move with the help of organelles-pseudopods, belong to rhizopods;
The class of rhizopods resembles algae, which indicates their relationship;
It feeds on those inherited from other plants, or from others, which distinguishes the amoeba from algae.
Amoeba - although the simplest, but a whole organism capable of leading an independent existence.
Amoeba Proteus is a single-celled animal that combines the functions of a cell and an independent organism. Outwardly, an ordinary amoeba resembles a small gelatinous lump only 0.5 mm in size, constantly changing its shape due to the fact that the amoeba constantly forms outgrowths - the so-called pseudopods, and, as it were, flows from place to place.
For such a variability in the shape of the body, the common amoeba was given the name of the ancient Greek god Proteus, who knew how to change his appearance.
The structure of the amoeba
The amoeba organism consists of a single cell, and contains a cytoplasm surrounded by a cytoplasmic membrane. The cytoplasm contains the nucleus and vacuoles - the contractile vacuole, which acts as an excretory organ, and the digestive vacuole, which serves to digest food. The outer layer of the cytoplasm of the amoeba is more dense and transparent, the inner one is more fluid and granular.
Amoeba proteus lives at the bottom of small fresh water bodies - in ponds, puddles, ditches with water.
amoeba nutrition
The common amoeba feeds on other unicellular animals and algae, bacteria, microscopic remains of dead animals and plants. Flowing along the bottom, the amoeba encounters prey, and envelops it from all sides with the help of pseudopods. At the same time, a digestive vacuole is formed around the prey, into which digestive enzymes begin to flow from the cytoplasm, due to which food is digested and then absorbed into the cytoplasm. The digestive vacuole moves to the cell surface anywhere, and merges with the cell membrane, after which it opens outward, and undigested food residues are thrown into the external environment. Digestion of food in one digestive vacuole takes the amoeba Proteus from 12 hours to 5 days.
Selection
In the process of life of any organism, including the amoeba, harmful substances are formed that must be excreted. To do this, the common amoeba has a contractile vacuole, into which dissolved harmful waste products constantly enter from the cytoplasm. After the contractile vacuole is filled, it moves to the cell surface and pushes the contents out. This process is repeated constantly - after all, the contractile vacuole is filled in a few minutes. Together with harmful substances, excess water is also removed during the excretion process. In protozoa living in fresh water, the concentration of salts in the cytoplasm is higher than in the external environment, and water constantly enters the cell. If excess water is not removed, the cell will simply burst. In protozoa, living in salty, sea water, there is no contractile vacuole; in them, harmful substances are removed through the outer membrane.
Breath
Amoeba breathes oxygen dissolved in water. How does this happen and why is breathing necessary? In order to exist, any living organism needs energy. If plants receive it in the process of photosynthesis, using the energy of sunlight, then animals receive energy as a result of chemical reactions of oxidation of organic substances that come with food. The main participant in these reactions is oxygen. In protozoa, oxygen enters the cytoplasm through the entire surface of the body and participates in oxidation reactions, while the energy necessary for life is released. In addition to energy, carbon dioxide, water and some other chemical compounds are formed, which are then excreted from the body.
amoeba reproduction
Amoebas reproduce asexually by dividing the cell in two. In this case, the nucleus first divides, then a constriction appears inside the amoeba, which divides the amoeba into two parts, each of which contains a nucleus. Then, along this constriction, the parts of the amoeba are separated from each other. If conditions are favorable, then the amoeba divides about once a day.
Under adverse conditions, for example, when a reservoir dries up, a cold snap, a change in the chemical composition of the water, and also in the fall, the amoeba turns into a cyst. In this case, the body of the amoeba becomes rounded, the pseudopods disappear, and its surface is covered with a very dense shell that protects the amoeba from drying out and other adverse conditions. Amoeba cysts are easily carried by the wind, and thus the amoeba colonizes other water bodies.
When environmental conditions become favorable, the amoeba leaves the cyst and begins to lead a normal, active lifestyle, feed and multiply.
Irritability
Irritability is a property of all animals to respond to various influences (signals) of the external environment. In an amoeba, irritability is manifested by the ability to respond to light - the amoeba crawls away from bright light, as well as to mechanical irritation and changes in salt concentration: the amoeba crawls away from the mechanical stimulus or from a salt crystal placed next to it.
Protozoa in a drop of pond water (under a microscope).
Rhizome class unites the simplest unicellular animals, whose body is devoid of a dense shell, and therefore does not have a permanent shape. They are characterized by the formation of pseudopods, which are temporarily formed outgrowths of the cytoplasm that promote movement and capture of food.
Habitat, structure and movement of the amoeba. The common amoeba is found in the silt at the bottom of the ponds with contaminated 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"). The details of the structure of the amoeba can only be examined under a microscope.
The body of the amoeba consists of a semi-liquid cytoplasm with a small vesicle enclosed inside it core. Amoeba consists of one cell, but this cell is a whole organism leading an independent existence.
Cytoplasm cells are 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 external resemblance of the pseudopods to the roots of plants.
Vital activity of 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.
Amoeba Breath. 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 and activity of the body is released.
Release of harmful substances life activity and excess water. 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. The digested food serves as material for building the body of the amoeba. The substances harmful to the amoeba are removed outside. There is a metabolism. Not only amoeba, but also all other living organisms cannot exist without metabolism both inside their body and with the environment.
Amoeba reproduction. The feeding of the amoeba leads to the growth of its body. The grown amoeba begins to reproduce. (? Probably due to exceeding a certain mass of her body.) 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.
Division (reproduction) of Amoeba.
Cyst. The amoeba feeds and reproduces 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 dries up where amoebas live. In the state of a cyst, the amoeba endures unfavorable living conditions for it. 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 dispersal (spread) of amoebae.
Possible additional questions for self-study.
- What makes the Cytoplasm systematically flow from one part of the Amoeba to another, forcing it to move in a given direction?
- How does the membrane of the cytoplasm of Amoeba recognize nutrients, as a result of which the amoeba purposefully forms pseudopods and a digestive vacuole?
Animals, like all organisms, are at different levels of organization. One of them is cellular, and its typical representatives are the amoeba proteus. We will consider the features of its structure and life activity in more detail below.
Subkingdom Unicellular
Despite the fact that this systematic group unites the most primitive animals, its species diversity already reaches 70 species. On the one hand, these are indeed the most simply arranged representatives of the animal world. On the other hand, these are simply unique structures. Just imagine: one, sometimes microscopic, cell is capable of carrying out all vital processes: respiration, movement, reproduction. Amoeba Proteus (the photo shows its image under a light microscope) is a typical representative of the Protozoa subkingdom. Its dimensions barely reach 20 microns.
Amoeba proteus: a class of protozoa
The very species name of this animal testifies to the level of its organization, since proteus means "simple". But is this animal so primitive? Amoeba Proteus is a representative of a class of organisms that move with the help of non-permanent outgrowths of the cytoplasm. Colorless blood cells that form human immunity also move in a similar way. They are called leukocytes. Their characteristic movement is called amoeboid.
What environment does the amoeba proteus live in?
The proteus amoeba that lives in polluted water bodies does no harm to anyone. This habitat is the most suitable, since in it the protozoan takes its important role in the food chain.
Structural features
Amoeba Proteus is a representative of the class, or rather the sub-kingdom of Unicellular. Its size barely reaches 0.05 mm. With the naked eye, it can be seen in the form of a barely noticeable jelly-like lump. But all the main organelles of the cell will be visible only under a light microscope at high magnification.
The surface apparatus of the amoeba Proteus cell is represented by which has excellent elasticity. Inside is a semi-liquid content - the cytoplasm. She moves all the time, causing the formation of pseudopods. Amoeba is a eukaryotic animal. This means that its genetic material is contained in the nucleus.
Movement of protozoa
How does the amoeba proteus move? This occurs with the help of non-permanent outgrowths of the cytoplasm. She moves, forming a protrusion. And then the cytoplasm smoothly flows into the cell. The pseudopods retract and form elsewhere. For this reason, the amoeba proteus does not have a permanent body shape.
Food
Amoeba Proteus is capable of phago- and pinocytosis. These are the processes of absorption by the cell of solid particles and liquids, respectively. It feeds on microscopic algae, bacteria and similar protozoa. Amoeba proteus (the photo below shows the process of capturing food) surrounds them with its pseudopods. Next, the food is inside the cell. A digestive vacuole begins to form around it. Thanks to digestive enzymes, particles are broken down, absorbed by the body, and undigested residues are removed through the membrane. By phagocytosis, blood leukocytes destroy pathogenic particles that penetrate the human and animal body every moment. If these cells did not protect organisms in this way, life would be practically impossible.
In addition to specialized nutritional organelles, inclusions can also be found in the cytoplasm. These are non-permanent cellular structures. They accumulate in the cytoplasm when there are necessary conditions for this. And they are spent when there is a vital need for it. These are grains of starch and droplets of lipids.
Breath
Amoeba Proteus, like all unicellular organisms, does not have specialized organelles for the respiration process. It uses oxygen dissolved in water or other liquid, when it comes to amoebas that live in other organisms. Gas exchange occurs through the surface apparatus of the amoeba. The cell membrane is permeable to oxygen and carbon dioxide.
reproduction
Amoeba is characterized by cell division in two. This process is carried out only in the warm season. It takes place in several stages. First, the nucleus is divided. It is stretched, separated by constriction. As a result, two identical nuclei are formed from one nucleus. The cytoplasm between them is torn apart. Its sections separate around the nuclei, forming two new cells. appears in one of them, and in the other, its formation occurs anew. Division occurs by mitosis, so the daughter cells are an exact copy of the parent. The process of amoeba reproduction occurs quite intensively: several times a day. So the life expectancy of each individual is quite small.
Pressure regulation
Most amoebas live in the aquatic environment. A certain amount of salts is dissolved in it. Much less of this substance in the cytoplasm of the simplest. Therefore, water must flow from the area with a higher concentration of the substance to the opposite one. These are the laws of physics. In this case, the body of the amoeba would have to burst from an excess of moisture. But this does not happen due to the action of specialized contractile vacuoles. They remove excess water with salts dissolved in it. At the same time, they provide homeostasis - maintaining the constancy of the internal environment of the body.
What is a cyst
Amoeba Proteus, like other protozoa, has adapted in a special way to the experience of adverse conditions. Her cell stops eating, the intensity of all vital processes decreases, the metabolism stops. The amoeba stops dividing. It is covered with a dense shell and in this form endures an unfavorable period of any duration. This happens periodically every autumn, and with the onset of heat, a unicellular organism begins to intensively breathe, feed and multiply. The same can happen in the warm season with the onset of drought. The formation of cysts has another meaning. It lies in the fact that in this state, the amoeba carries the wind over considerable distances, settling this biological species.
Irritability
Of course, these simplest unicellular organisms are not talking about the nervous system, because their body consists of only one cell. However, this property of all living organisms in the amoeba Proteus manifests itself in the form of taxis. This term means a response to the action of stimuli of various kinds. They may be positive. For example, an amoeba clearly moves towards food objects. This phenomenon, in fact, can be compared with the reflexes of animals. Examples of negative taxis are the movement of the amoeba proteus from bright light, from an area of high salinity or mechanical stimuli. This ability is primarily defensive.
So, the amoeba proteus is a typical representative of the sub-kingdom Protozoa or Unicellular. This group of animals is the most primitively arranged. Their body, however, it is able to perform the functions of the whole organism: breathe, eat, multiply, move, respond to irritations and adverse environmental conditions. Amoeba proteus is part of the ecosystems of fresh and salt water bodies, but is able to live in other organisms. In nature, it is a participant in the circulation of substances and the most important link in the food chain, being the basis of plankton in many water bodies.
Amoeba proteus or common amoeba- lat. Amoeba proteus. Amoeba proteus or is a huge amoeboid organism, a representative of the class lobous amoeba, belongs to the type protozoa. Found in fresh waters, aquariums.
In a drop of water taken from a pond, swamp, ditch or aquarium, when viewed under a microscope, a whole world of living beings opens up. Among them are tiny translucent invertebrates, constantly changing the shape of their body.
An ordinary amoeba, like a ciliate shoe, is the simplest animal in its structure. To examine an ordinary amoeba, you need to place a drop of water with amoebas under a microscope. The entire body of an ordinary amoeba consists of a tiny gelatinous lump of living matter - protoplasm with a nucleus inside. From the course of botany it is known that a lump of protoplasm with a nucleus is a cell. So, an ordinary amoeba is a unicellular invertebrate animal. Its body consists only of protoplasm and nucleus.
Observing the amoeba Proteus under a microscope, we notice that after a while the shape of its body changes. Amoeba Proteus does not have a permanent body shape. Therefore, it received the name "amoeba", which means "changeable" in Greek.
Also under a microscope, you can see that it slowly creeps onto the darkened part of the glass. Bright sunlight quickly kills common amoebas. If you add a crystal of table salt to a drop of water, the amoeba stops moving, retracts the pseudopods and acquires a spherical shape. Thus, ordinary amoebas reduce the surface of the body, which is affected by a salt solution harmful to them. This means that ordinary amoeba are able to respond to external stimuli. This ability is called irritability. It connects the common amoeba with the external environment and has a protective value.
Common amoebas can be found even in ditches and puddles that have formed recently. When the reservoir in which ordinary amoeba and other protozoa live begins to dry up, they do not die, but are covered with a dense shell, turning into a cyst. In this state, amoeba and other protozoa can tolerate both high temperatures (up to +50, +60 °) and strong cooling (up to -273 degrees). The cysts are carried by the wind over considerable distances. When such a cyst again finds itself in favorable conditions, it begins to feed and multiply. Thanks to this adaptation, ordinary amoeba survive unfavorable living conditions for them and settle throughout the planet. The movement of the amoeba occurs with the help of pseudopods.
The amoeba feeds on bacteria, algae, microscopic fungi. With the help of pseudopods (because of which the amoeba moves), it captures food.
Amoeba Proteus, like all animals, needs oxygen. Amoeba respiration is carried out due to the assimilation of oxygen from water and the release of carbon dioxide.
Common amoeba reproduce by division. In this case, the core of the amoeba lengthens, and then divides in half.
