Amoebaordinary(lat. Amoeba proteus)
or amoeba proteus(rhizopod) - amoeboid organism, representative of the class Lobosa(lobosal amoebas). Polypodial form (characterized by the presence of numerous (up to 10 or more) pseudopodia - pseudopodia). Pseudopodia constantly change their shape, branch, disappear and reappear.
Cell structure
A. proteus is externally covered only with plasmalemma. The cytoplasm of the amoeba is clearly divided into two zones, ectoplasm and endoplasm (see below).
Ectoplasm, or hyaloplasm, lies in a thin layer directly under the plasmalemma. Optically transparent, free of any inclusions. The thickness of the hyaloplasm in different parts of the amoeba’s body is different. On the lateral surfaces and at the base of the pseudopodia this is usually a thin layer, and at the ends of the pseudopodia the layer noticeably thickens and forms the so-called hyaline cap, or cap.
Endoplasm, or granuloplasm - the internal mass of the cell. Contains all cellular organelles and inclusions. When observing a moving amoeba, a difference in the movement of the cytoplasm is noticeable. The hyaloplasm and peripheral portions of the granuloplasm remain practically motionless, while its central part is in continuous motion; cytoplasmic currents with organelles and granules involved in them are clearly visible. In a growing pseudopodia, the cytoplasm moves to its end, and from shortening ones - to central part cells. The mechanism of hyaloplasm movement is closely related to the process of transition of the cytoplasm from a sol to a gel state and changes in the cytoskeleton.
Nutrition
Amoeba Proteus feeds by phagocytosis, absorbing bacteria, single-celled algae and small protozoa. The formation of pseudopodia underlies food capture. On the surface of the amoeba’s body, contact occurs between the plasmalemma and the food particle, and a “food cup” is formed in this area. Its walls close, and digestive enzymes begin to flow into this area (with the help of lysosomes). This way it is formed digestive vacuole. Then it passes into the central part of the cell, where it is picked up by cytoplasmic currents. In addition to phagocytosis, amoeba is characterized pinocytosis- swallowing liquid. In this case, an invagination in the form of a tube is formed on the surface of the cell, through which a drop of liquid enters the cytoplasm. The forming vacuole with liquid is detached from the tube. After the liquid is absorbed, the vacuole disappears.
Defecation
Endocytosis (excretion). The vacuole with undigested food remains approaches the surface of the cell and merges with the membrane, thus throwing the contents out.
Osmoregulation
The cell periodically produces a pulsating contractile vacuole- a vacuole that contains excess water and removes it out.
Reproduction
Only agamic, binary fission. Before division, the amoeba stops crawling, its dictyosomes, Golgi apparatus and contractile vacuole disappear. First, the nucleus divides, then cytokinesis occurs. The sexual process is not described.
Causes indigestion and colitis (bloody diarrhea).
The cytoplasm is completely surrounded by a membrane, which is divided into three layers: outer, middle and inner. The inner layer, which is called endoplasm, contains the necessary elements for an independent organism:
- ribosomes;
- elements of the Golgi apparatus;
- supporting and contractile fibers;
- digestive vacuoles.
Digestive system
A unicellular organism can actively reproduce only in moisture; in the dry habitat of the amoeba, nutrition and reproduction are impossible.
Respiratory system and response to irritation
Amoeba proteus
Amoeba division
The most favorable living environment is found in the reservoir and human body . Under these conditions, the amoeba multiplies quickly, actively feeds on bacteria in bodies of water and gradually destroys the tissues of the organs of its permanent host, which is a person.
Amoeba reproduction occurs asexually . Asexual reproduction involves cell division and the formation of a new one-celled organism.
It is noted that one adult can divide several times a day. This determines the greatest danger for a person who suffers from amoebiasis.
That is why, at the first symptoms of the disease, doctors strongly recommend seeking help from a specialist rather than starting self-medication. Incorrectly selected medications can actually cause more harm to the patient than good.
In contact with
Most simplest organism- amoeba proteus, although they exist different types amoeb. It got its name in honor of Proteus - the character Greek mythology, whose feature was to change his appearance. The creature is a prokaryote because it is not a bacterium, as many people think. This is a colorless organism of the heterotrophic type, eukaryotes, which is capable of feeding on microorganisms and unicellular algae. Despite its simplicity and short life cycle, this type of animal plays important role in nature.
Description
According to the classification, the common amoeba belongs to the kingdom “Animals”, the subkingdom “Protozoa”, and the class of free-living sarcodes. The structure of the creature is primitive, and it moves thanks to temporarily appearing protrusions of the cytoplasm (also called a rhizome). The body of Proteus consists of only a single cell, which is an independent and complete organism.
The common amoeba is a eukaryote, a single-celled independent animal. Its characteristics are as follows: the body is semi-liquid, the size reaches 0.2-0.7 mm in length, and the creature can only be clearly seen under a microscope. The entire surface of the amebic cell is covered with cytoplasm, which protects the “insides”. On top is the cytoplasmic membrane. The amoeba has a two-layer cytoplasm. The outer layer is transparent and dense, the inner layer is granular and fluid. The cytoplasm contains the contractile vacuole of the amoeba (due to which unnecessary substances are released out), the nucleus and the digestive vacuole. When moving, the shape of the cytoplasm constantly changes. After examining the images, scientists determined that Proteus has more than five hundred chromosomes, so small that they cannot be observed.
Breathing is carried out throughout the body. The skeleton is missing. Amoeba reproduction is asexual. The amoeba cell also does not have a sense organ (including breathing).
Nevertheless, unicellular amoeba breathes, sensitive to chemicals, mechanical irritants and avoids sun rays.
One of the characteristics of the animal is the ability to regenerate. This means that in case of damage, the cell will be able to repair itself by completing the missing fragments. The only condition is full preservation core, since it is the carrier of all information data about the structure. Without a nucleus, the amoebic organism will simply die.
The movement of amoebas occurs with the help of pseudopods, the so-called non-permanent outgrowths of the cytoplasm, which are also called pseudopodia. The cell membrane is very elastic and can stretch anywhere. To form a pseudopod, cytoplasm first protrudes outward from the body, so that it looks like thick tentacles. After - the same actions are performed, only in reverse order– the cytoplasm moves inward, the pseudopod hides and appears in another part of the body. It is this method of movement that prevents the animal from having permanent form bodies. Despite their small size, the creatures move relatively quickly - about 10 mm/hour.
Amoeba moves with the help of pseudopods, which is why it does not have a constant body shape
How do single-celled animals eat and breathe?
The amoebic life cycle depends entirely on how the animal feeds and what environment. The diet of Proteus includes the remains of decay, unicellular algae, bacteria, as well as microorganisms of suitable size. The amoeba feeds by capturing “prey” with its pseudopods and dragging it inside the body. A vacuole is formed around the food, into which digestive juice then enters. Interestingly, the process of capture and further digestion can occur in any part of the body and even in several parts at the same time. Obtained by digestion nutrients enter the cytoplasm and are spent on building the body of the amoeba. In the process of resorption of algae and bacteria, protozoa immediately remove the remains of vital activity to the outside, and this can also occur in any part of the cytoplasm.
Like all protozoa of the unicellular class, Proteas lack special organelles. Respiration in amoeba occurs due to the absorption of oxygen dissolved in water (or liquid) by the surface apparatus. Cell membrane animal is permeable, and through it pass freely carbon dioxide and oxygen.
How do they reproduce?
To produce offspring, asexual reproduction is used with the division of the body into two identical parts. Learn more about how many stages a cell goes through when dividing.
The process occurs only in warm seasons and includes several stages:
- The first thing that undergoes fission is the nucleus. It protrudes, stretches, constrictions appear in it, with the help of which it then divides into two completely identical parts. In this case, the divergence of daughter chromosomes to the opposite poles of the mother cell is observed.
- Next, the cytoplasm is divided between the two nuclei. Its zones are located and concentrated around the nuclei, thereby forming two new cells.
- Since in the body of the amoeba the contractile vacuole is present only in a single copy, it goes to only one new cell. In another, it is formed anew. A more detailed description of the process of division and divergence of chromosomes is shown in the figure.
Cell division in this way is called mitosis, so the resulting two organisms are a copy of the “mother”. There is no sexual process, so chromosome exchange also does not occur.
Reproduce common amoebas very fast. Judging by time, the creature divides into 2 cells every 3 hours, so the amoebic organism does not live long.
Features of existence and development
The life cycle is simple. A single cell, which is also the body of an animal, grows during development, and upon reaching the adult state, “multiplies”, dividing into two bodies asexually with the divergence of maternal chromosomes to “children”. Finding itself in conditions negative for life (cold season, drying out of the reservoir), such a cell is able to “die” for a while. At the same time, the body undergoes changes: the pseudopodia are retracted, water is released from the cytoplasm and covers the entire amoebic organism, forming a double shell with the subsequent formation of a cyst. Protea “freezes.” When the environment becomes habitable, the creature is "reborn", the amoeba cyst breaks open, prolegs are released (to move around), and the creature reproduces. You can find out in detail what an amoeba is in the video.
The animal has great value in nature. It is a source of food multicellular organisms(worms, crustaceans, fish fry, and various mollusks feed on amoebas). Protea, which lives in water bodies, cleans water bodies during its life by eating various types microorganism, bacteria and decaying parts of algae, protozoan testate amoebas are involved in the formation of chalk deposits and limestones.
Among the simplest organisms, the amoeba is considered the most primitive. The bacterium has microscopic dimensions and is a single-celled creature.
Amoeba is the simplest single-celled creature
Amoeba - what is it?
Amoeba (rhizopod)- most low rank Living creatures. What is it - a bacterium or an animal? The microorganism is one of the simplest single-celled animals, has tiny dimensions (from 0.2 to 0.5 mm), and the body shape changes all the time depending on external conditions. Single-celled creatures, like more complex animals, use oxygen for breathing, and external environment release carbon dioxide.
Kinds
At unfavorable conditions(temperature jumps, drying out of ponds, air currents) 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 durable two-layer shell. Infection occurs through food (poorly washed fruits and vegetables), contaminated water, and dirty hands.
Structure
The amoeba does not have a skeleton, a formed mouth, lungs or gills.
Its structure is made up of organelles:
- large 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 amoeba’s body).
What an amoeba looks like and what it consists of is shown in the photo.
Amoeba has a simple structure
Nutrition
The rhizome feeds using pseudopodia. The process of capturing solid food is called phagocytosis. Capturing food is one of the main functions of the false legs: they grasp edible particles, which helps the latter enter the nutritional vacuole, where they are enveloped by a membrane. Digestion gradually occurs, the excess of which comes out of the contracting vacuole during the movement of the amoeba.
The process of food capture by amoeba
Reproduction
Amoebas can only reproduce asexually. Having reached maturity, the cell begins division, which results in 2 daughter organisms.
How they reproduce:
- change in the core (first it stretches, then lengthens, as a result of which it is pulled in the middle);
- division of the nucleus into two halves (formation of two independent nuclei);
- division of the amoeba itself into two new cells, each of which has its own nucleus.
Amoebas reproduce asexually
During the appearance of a daughter microorganism, the formation of organelles missing for the new cell occurs. In 24 hours, an amoeba can undergo the process of binary fission several times.
Life cycle
Amoeba has a simple life cycle. IN favorable environment cells develop, grow and divide asexually. When living conditions worsen, amoebas “freeze,” thereby forming cysts. When microorganisms enter the human body, animal body, water bodies or moist soil, they come to life, are released from the protective shell and begin to actively multiply.
When environmental conditions worsen, amoebas become covered containment(cyst)
Symptoms of amoebiasis
Signs of amoebiasis largely depend on the type of disease:
- Intestinal amebiasis (dysenteric amoebic colitis, amoebic dysentery). Characteristic symptoms: profuse diarrhea streaked with blood, mucus and pus. As the disease progresses, the negative manifestations in the form of increased body temperature, chills, vomiting, loss of appetite. During defecation, cramping pain in the lower abdomen is possible, which calm state less pronounced.
- Extraintestinal type of disease - occurs as a complication of intestinal amebiasis. Most often it affects the liver (abscess or amoebic hepatitis). Symptoms: enlargement of the affected organ, painful sensations in the right hypochondrium, the appearance of jaundice, heat(up to 40 degrees).
When the liver is damaged by amoebas, pain appears in the right hypochondrium
Amoebiasis has a mild course (fever, diarrhea, yellowness of 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, and genitourinary system.
Diagnostics
The diagnosis of amoebiasis is based on 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.
Endoscopic examination is used to determine the extent of damage to the rectum
Treatment of amoebiasis
Drugs that have a detrimental effect on amoebas are divided into 2 main groups:
- contact (luminal) - Clefamide, Paromomycin, Etofamide - are used for asymptomatic amoebiasis, as well as for the prevention of relapses;
- tissue - Tinidazole, Ornidazole, Metronidazole - prescribed for intestinal amebiasis, as well as in the treatment of abscesses in the liver, lungs, and brain.
Intestinal disease caused by amoebas responds well to therapy and is almost completely cured with early stages the course of the pathology.
Metronidazole helps with intestinal amebiasis
Prevention
Infection with protozoa can be prevented by following simple preventive measures:
- use only boiled water(boil for at least 10 minutes);
- Wash vegetables and fruits well before use;
- make sure that flies do not land on food (cover with protective film);
- adhere to the rules of personal hygiene (wash hands after visiting the toilet, before eating, after visiting public places and walking outside);
- Do not fertilize garden beds with human feces.
Amoebas are the simplest animals that consist of a single cell. Among the primitive microorganisms there is a dangerous species - dysenteric amoeba (not to be confused with the causative agents of malaria), 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 contact with a specialist make it possible to prevent dangerous consequences.