“The simplest test” - Movement. Characteristic features of protozoa. Amoeba nutrition. Cyst formation. Big core. They move with the help of pseudopods, flagella or cilia. Class Flagellates. Signs of the animal Movement with the help of flagella, heterotrophic method of feeding in the dark. Breathes throughout the entire surface of the body. Class Ciliates.
“Protozoa biology” - Reproduce by cell division. Diversity of Protozoa. Amoeba Proteus. Scorched frog. May form cysts. Questions on the topic Protozoa. Name the four classes of the Kingdom of Protozoa. General signs of the Kingdom of Protozoa. Plasmodium vivax. Acantaria. Give examples of protozoa that pose a danger to people.
“The simplest animals” - Medusa. Sea anemone. Worms. What is the role of different animals in ecosystems? Purify the water. slug Orion. Flat. General. Octopus. Foraminifera shells. Shellfish. Sponge. Tropical scallop. Oysters. Bivalve mollusk. Squid. Plants can. Red coral. Hydromedusa. Ciliate - shoe.
“Protozoa” - Protozoa include animals consisting of one or more cells - colonies. Class Flagellates. Eating -? Tolerate unfavorable conditions - ? Classification of the type Protozoa. Class Sarcodae (Rhizopods). Class Sporozoans. Class Ciliates. Historical reference. Representatives of protozoa. Variety of animals.
The symbiosis of termites and flagellates living in their intestines, as well as nitrogen-fixing bacteria and bacteria that process cellulose, is another example of the perfect adaptation of living organisms to the environment. After all, a number of termite species feed almost exclusively on dead wood, which is essentially pure cellulose - a product containing a significant amount of energy, but practically indigestible in the body of animals. The necessary enzymes are available in sufficient quantities only in representatives of the unicellular world. It is them, their guests (or “pets”), that the termite “feeds” wood. Microorganisms capable of digesting cellulose, in turn, share the resulting energy with bacteria capable of chemically fixing free nitrogen - after all, there is practically no protein left in dead wood. As a result, the termite's intestinal cohabitants accumulate nutrients in their cells that are completely accessible to the termite itself for digestion and contain not only energy, but also protein, including all types of amino acids necessary for the insect.
Various flagellates from the intestines of termites: A – Teratomipha mirabilis; B – Spirotrichonympha flagellata; B – Coronympha octonaria; D – Calonympha grassi; D – Trichonympha turkestana; E – Rhynchonympha tarda; 1 – core; 2 – axostyles
Class of collared flagellates (Choanoflagellatea) includes 100 species of small (0.005 - 0.02 mm) organisms, the cells of which have one flagellum. The base of this flagellum is surrounded by a corolla of microvilli called collared and serves to filter food particles (bacteria) suspended in water, driven by the water current to the base of the flagellum. On the outside, near the base of the collar, small pseudopods (pseudopodia) are formed, capturing a suspension of nutrients from the water. Collared protists are free-living protists, among which there are both planktonic (i.e. free-swimming) and sessile; both solitary and colonial forms. The nuclei of collared flagellates contain a double set of chromosomes, but the sexual process in them is unknown.
To the sarcode type ( Sarcodina) include protists capable of forming so-called pseudopods, or pseudopodia - mobile outgrowths of the cytoplasm that protrude beyond the general contours of the cell body. Sarcodidae pseudopods can be lobe-shaped or cylindrical, thread-like, branching and merging with each other like a mesh. It happens that they have a supporting frame of longitudinal microtubules. The shape and structure of the pseudopods serve as the characteristic on the basis of which sarcodidae are divided into separate classes and orders. Most sarcodae are free-living predatory organisms that feed on unicellular algae, flagellates, ciliates, as well as bacteria, which they capture with their pseudopods and digest. Sarcodae are distributed throughout the globe and are found in bodies of water with varying salinity, as well as in soil.
Rhizome class (Rhizopoda) includes several orders. To the squad true amoebas (Euamoebida) refers to 200–250 species of protists with lobe-shaped pseudopodia, with the help of which they “crawl” along the substrate, and do not have any shells characteristic of other rhizomes. Some species have a fan shape, with an expanded anterior end, on which pseudopodia are formed, others are cylindrical and, with active movement, form only one anterior pseudopodia. The cell sizes of these organisms range from 0.005 to 0.02 mm.
Most true amoebas are benthic organisms that live in the sediment. However, sometimes - in order to move to a new place - they can become rounded for a short time and release longer and thinner (radiant) pseudopodia, thanks to which they float in the water column and are carried by its flow. True amoebas reproduce by simple mitotic division into two. The nucleus of the cells of these organisms contains a double set of chromosomes, but until now no one has ever observed the sexual process in them.
Order of rhizomes schizopyrenide (Schizopyrenida) includes about 100 species of small (0.005 - 0.01 mm) mainly soil protists. They are distinguished from true amoebas by the presence of a pulsating zone (“hyaline cap”) at the anterior end, as well as the ability of most species to form special dispersal stages equipped with 2–4 flagella. Schizopyrenids reproduce, like true amoebas, by simple mitotic division in two; their sexual process is unknown.
To the squad entamoeba (Entamoebida) include about 50 species of protists living in the intestinal tract of vertebrates. There they feed on both the food that gets there and the tissues of the intestine itself, but usually do not cause any significant harm to the host’s body. However, entamoeba species Entamoeba histolitica, which lives in the human intestine, under certain conditions forms a special form that penetrates the peri-intestinal tissues and liver and destroys them, as well as eating red blood cells. This disease is called amoebic dysentery and is found in tropical countries. Representatives of the same species of entamoeba, living in the intestines of residents of the middle zone, do not form a dangerous form.
A characteristic feature of entamoebas is the absence of mitochondria and the Golgi apparatus in their cells. However, this is probably not a primitive feature, but a secondary simplification - after all, in the intestinal conditions, mitochondria responsible for oxygen respiration are simply not needed.
Squad testate amoebae
(Testacida) includes about 300 species of protozoa, the body of which is surrounded by a single-chamber shell, in which there is an opening for the exit of pseudopodia. This shell can be built from a protein similar in composition to keratin, which forms our hair and nails, from silica plates secreted by the cell, or from cemented grains of sand. The usual shell size is 0.05–0.2 mm.
Testate amoebas are found mainly in fresh water bodies and in soil, and, on the contrary, are rare in the seas.
These protists reproduce by mitotic division in two, with one of the resulting individuals remaining in the old shell, while the other surrounds itself with a new one. However, testate amoebae also have a sexual process, and it can proceed differently in different forms. In some cases, the nuclei of testate amoebae carry a double set of chromosomes, but at a certain point the cell forms a cyst in which reduction division occurs. A pair of haploid sex nuclei appears, which then merge with each other again - this sexual process is called autogamy. In another case, the nuclei of amoebas, on the contrary, are haploid, but at a certain period a pair of individuals merges, after which the resulting cell with a diploid nucleus immediately divides by meiosis. It is interesting that representatives of the first group have lobe-shaped, while the second group has filamentous pseudopods. Probably, these amoebas, despite the presence of similar shells, are not related to each other, and their combination into one order is artificial.
To the squad foraminifera (Foraminiferida) include about 10 thousand living and about 20 thousand more fossils, known from the remains of shells, species of rhizomes. Foraminifera are distinguished by thin branching pseudopods and have an organic, calcareous, or cemented shell from grains of sand. In primitive forms it is single-chambered, while in higher forms it is multi-chambered, divided into compartments connected by pores. The shape of the shell in different foraminifera can be very diverse - round, elongated, twisted, resembling a berry... Usually its dimensions range from 0.05 to 0.5 mm, but tubular forms are found in the thickness of marine sediments (for example, Bathyosiphon) up to several centimeters in size!
Symbiont bacteria that decompose wood for termites also fix atmospheric nitrogen for them
Until recently, it was a mystery how termites managed to live (and even thrive) on wood alone. It was known that the decomposition of the cellulose consumed by them is carried out by bacteria - intracellular symbionts of protozoa, which in turn live in the intestines of the termite. But cellulose is a low-nutrient substrate; in addition, it cannot serve as a source of nitrogen, which termites need in much greater quantities than is contained in plant tissues. However, a striking conclusion was recently reached by a group of Japanese researchers who began studying the composition of the genome of symbiotic bacteria of flagellates. Along with the genes responsible for the synthesis of cellulase - an enzyme that destroys cellulose molecules, the genome contains genes encoding enzymes responsible for nitrogen fixation - binding free atmospheric nitrogen N2 and converting it into a form suitable for use not only by bacteria themselves, but also by flagellates and termites.
People who are far from biology sometimes confuse termites with ants, since both lead a colonial lifestyle, erect large buildings (termite mounds and anthills), and in addition, are characterized by the division of labor between separate groups of individuals: they have workers, soldiers, as well as females (queens) and males producing offspring.
However, the similarity between ants and termites is purely external, explained by the social way of life that arose in both groups. In fact, these insects belong to different, far from related, orders. Ants are hymenoptera, relatives of wasps and bees. Termites form a special order, and, unlike Hymenoptera, they are insects with incomplete transformation (they do not have a pupa, and the larva, through a series of successive molts, gradually becomes more and more similar to an adult insect).
Termites are not found in temperate, much less northern latitudes, but they are extremely numerous in the tropics, where they are the main consumers of plant debris. Unlike many other animals, termites can feed on wood alone - more precisely, fiber (cellulose), which they process extremely quickly. Any wooden structure erected in the tropics is susceptible to the destructive activity of termites. A house without special protection could be eaten by termites within a few years.
Researchers have long been interested in the question: how do termites cope with the decomposition of fiber (after all, this has always been considered the prerogative of bacteria and fungi!) and how can they even get by with such low-nutrient food? For a long time it was believed that protozoa, representatives of a special group of flagellates that live in the intestines of termites, help termites in processing fiber. But later it turned out that flagellates themselves need the help of endosymbionts - bacteria living in their cells (endosymbiont means “living in a cell”), which produce cellulase, an enzyme that decomposes cellulose.
Thus, this entire symbiotic system is structured according to the matryoshka principle: flagellates live in the intestines of the termite, and bacteria live inside the flagellates. Termites find food (plant debris or wooden structures), grind the wood mass and bring it to a fine state in which flagellates can absorb it. Then the bacteria living inside the flagellate get down to business, carrying out the basic chemical reactions to process the initially inedible product into a completely digestible form.
However, much about this system remained unclear. For example, it was unknown where termites get the nitrogen they need (and its relative content in the bodies of animals, including termites, is significantly higher than in plant tissues). However, recent research by Japanese scientists has answered this question.
The object of research by Yuichi Hongoh and his colleagues from the RIKEN Advanced Science Institute, Saitama and other scientific institutions in Japan was the symbiotic system of the termite that is widespread in Japan Coptotermes formosanus. This species, leading an underground lifestyle, is known as a malicious pest, causing enormous damage to wooden structures, not only in its homeland, in Southeast Asia, but also in America, where it was accidentally introduced. To fight with Coptotermes formosanus In Japan, several hundred million dollars are spent annually, and in the United States - about a billion.
Flagellates living in the hind intestine of termites Pseudotrichonympha grassii belong to a genus whose representatives are often found in various termites leading an underground lifestyle. Each flagellate is constantly inhabited by about 100 thousand bacteria belonging to the order Bacteroidales and having the code name “phylotype CfPt1-2”.
During the work, flagellates were removed from the termite intestines, the membranes of their cells were destroyed, and 10 3 -10 4 cells of endosymbiotic bacteria were released from each. The resulting mass of bacteria was subjected to amplification (increasing the number of copies of DNA molecules present there), after which a search for certain gene sequences was carried out. In the circular chromosome containing 1,114,206 base pairs, 758 putative protein-coding sequences, 38 transfer RNA genes and 4 ribosomal RNA genes were identified. The discovered set of genes made it possible to reconstruct in general terms the entire metabolic system of the endosymbiotic bacterium.
The most striking thing was the discovery of genes responsible for the synthesis of those enzymes that are necessary for nitrogen fixation - the process of binding atmospheric N 2 and converting it into a form convenient for use by the body. In particular, genes were found that are responsible for the synthesis of nitrogenase, the most important enzyme that cleaves the strong triple bond in the N2 molecule, as well as genes encoding other proteins necessary for nitrogen fixation.
The authors of the work under discussion note that, in fact, the ability of termites to fix nitrogen had already been discovered earlier, but it was unclear which symbiotic organisms were responsible for it. The identification of genes responsible for nitrogen fixation in the studied endosymbiotic bacteria came as a surprise, since nitrogen fixation had never been observed in bacteria of this group (Bacteriodales) before. In addition to binding N2 and converting it into NH3, the studied bacteria are apparently capable of utilizing those products of nitrogen metabolism that are formed during the metabolism of the protozoa themselves. This is an important point, since the binding of N2 requires large energy costs, and if there is enough nitrogen in the termite food, then the intensity of nitrogen fixation can be reduced.
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Relationships between organisms
Living organisms do not settle with each other by chance, but form certain communities adapted to living together. Among the huge variety of relationships among living beings, certain types of relationships are distinguished that have much in common among organisms of different systematic groups. According to the direction of action on the body, they are all divided into positive, negative and neutral.
Symbiosis- cohabitation (from the Greek sym - together, bios - life), a form of relationship in which both partners or one of them benefits from the other. There are several forms of mutually beneficial cohabitation of living organisms.
Fig 1. Cancer is a hermit
and polychaete worm Fig. 2. cleaner birds
Mutualism. A widespread form of mutually beneficial cohabitation is when the presence of a partner becomes a prerequisite for the existence of each of them. One of the most famous examples of such relationships is lichens, which are cohabitations of a fungus and an algae. In lichen, the hyphae of the fungus, entwining the cells and filaments of algae, form curly shoots that penetrate the cells. Through them, the fungus receives photosynthesis products formed by algae. The algae extracts water and mineral salts from the hyphae of the fungus.
Typical symbiosis- the relationship between termites and flagellated protozoa living in their intestines. Termites eat wood, but they do not have enzymes to digest cellulose. Flagellates produce such enzymes and convert fiber into simple sugars. Without protozoa - symbionts - termites die of starvation. The flagellates themselves, in addition to a favorable microclimate, receive food and conditions for reproduction in the intestines of termites. Intestinal symbionts involved in the processing of rough plant feed are found in many animals: ruminants, rodents, borers, etc.
Mutualism is also widespread in the plant world. An example of a mutually beneficial relationship is the cohabitation of the so-called nodule bacteria and legumes(peas, beans, soybeans, clover, alfalfa, vetch, black locust, ground nuts, or peanuts). These bacteria, capable of absorbing nitrogen from the air and converting it into ammonia and then into amino acids, settle in the roots of plants. The presence of bacteria causes the growth of root tissues and the formation of thickenings - nodules. Plants in symbiosis with nitrogen-fixing bacteria can grow on soils poor in nitrogen and enrich the soil with it.
Plants also use other species as habitats. An example is epiphytes. Epiphytes can be algae, lichens, mosses, ferns, flowering plants, and woody plants; they serve as a place of attachment, but not as a source of nutrients or mineral salts. Epiphytes feed on dying tissues, host secretions, and through photosynthesis. In our country, epiphytes are represented mainly by lichens and some mosses.
Symbiosis
Symbiosis 1 - cohabitation (from the Greek sim - together, bios - life) is a form of relationship from which both partners or at least one benefit.
Symbiosis is divided into mutualism, protocooperation and commensalism.
Mutualism 2 - a form of symbiosis in which the presence of each of the two species becomes obligatory for both, each of the cohabitants receives relatively equal benefits, and the partners (or one of them) cannot exist without each other.
A typical example of mutualism is the relationship between termites and flagellated protozoa that live in their intestines. Termites eat wood, but they do not have enzymes to digest cellulose. Flagellates produce such enzymes and convert fiber into sugars. Without protozoa - symbionts - termites die of starvation. In addition to a favorable microclimate, the flagellates themselves receive food and conditions for reproduction in the intestines.
Protocooperation 3 - a form of symbiosis in which coexistence is beneficial to both species, but not necessarily to them. In these cases, there is no connection between this particular pair of partners.
Commensalism - a form of symbiosis in which one of the cohabiting species receives some benefit without bringing any harm or benefit to the other species.
Commensalism, in turn, is subdivided into tenantry, co-feeding, and freeloading.
"Tenancy" 4 - a form of commensalism in which one species uses another (its body or its home) as a shelter or home. Of particular importance is the use of reliable shelters for the preservation of eggs or juveniles.
The freshwater bitterling lays its eggs in the mantle cavity of bivalve mollusks - toothless. The laid eggs develop under ideal conditions of a clean water supply.
"Companionship" 5 - a form of commensalism in which several species consume different substances or parts of the same resource.
"Freeloading" 6 - a form of commensalism in which one species consumes the food scraps of another.
An example of the transition of freeloading into closer relationships between species is the relationship between the sticky fish, which lives in tropical and subtropical seas, with sharks and cetaceans. The front dorsal fin of the sticker has been transformed into a suction cup, with the help of which it is firmly held on the surface of the body of a large fish. The biological meaning of the attachment of sticks is to facilitate their movement and settlement.
Neutralism
Neutralism 7 - a type of biotic relationship in which organisms living together in the same territory do not affect each other. In neutralism, individuals of different species are not directly related to each other.
For example, squirrels and moose in the same forest do not contact each other.
Antibiosis
Antibiosis - a type of biotic relationship when both interacting populations (or one of them) experience negative influence from each other.
Amensalism 8 - a form of antibiosis in which one of the cohabiting species oppresses another without receiving either harm or benefit from it.
Example: light-loving herbs growing under a spruce suffer from severe darkening, while they themselves do not affect the tree in any way.
Predation 9 - a type of antibiosis in which members of one species feed on members of another species. Predation is widespread in nature among both animals and plants. Examples: carnivorous plants; lion eating antelope, etc.
Co-Competition - a type of biotic relationship in which organisms or species compete with each other to consume the same, usually limited, resources. Competition is divided into intraspecific and interspecific.
Intraspecific competition 10 - competition for the same resources that occurs between individuals of the same species. This is an important factor in self-regulation of the population. Examples: Birds of the same species compete for nesting sites. During the breeding season, males of many mammal species (for example, deer) compete with each other for the opportunity to start a family.
Interspecific competition 11 - competition for the same resources that occurs between individuals of different species. Examples of interspecific competition are numerous. Both wolves and foxes hunt hares. Therefore, competition for food arises between these predators. This does not mean that they directly come into conflict with each other, but the success of one means the failure of the other.
For example, lampreys attack cod, salmon, smelt, sturgeon and other large fish, and even whales. Having attached itself to the victim, the lamprey feeds on the juices of its body for several days, even weeks. Many fish die from the numerous wounds it inflicts.
All of the listed forms of biological connections between species serve as regulators of the number of animals and plants in the community, determining its stability.
4.Living environments and habitats of animals. Adaptation of animals to habitats page 10 of the textbook
Aquatic environment: High density
Severe pressure changes
Strong absorption of sunlight
Salt regime
Current speed
Soil properties
Ground-air environment: Gaseous with low density
Low amount of water vapor
Different light intensities and temperatures
Soil environment: Solid boundaries surrounded by air and water
Smoothed out temperature fluctuations
Light plays virtually no role
Soil structure, moisture, chemical composition
Organismal environment: Abundance of food
Relative stability of conditions
Protection from adverse environmental factors
Active resistance of the host organism
Implementation of the life cycle is difficult
Animal habitats and habitats
Examples of adaptation in the animal world. Various forms of protective coloration are widespread in the animal world. They can be reduced to three types: protective, warning, camouflage.
Protective coloration helps the body become less noticeable against the background of the surrounding area. Among green vegetation, bugs, flies, grasshoppers and other insects are often colored green. The fauna of the Far North (polar bear, polar hare, white partridge) is characterized by white coloring. In deserts, yellow tones predominate in the colors of animals (snakes, lizards, antelopes, lions).
Warning coloring clearly distinguishes the organism in the environment with bright, variegated stripes and spots (endpaper 2). It is found in poisonous, burning or stinging insects: bumblebees, wasps, bees, blister beetles. Bright, warning coloring usually accompanies other means of defense: hairs, spines, stings, caustic or pungent-smelling liquids. The same type of coloring is threatening.
Disguise can be achieved by resemblance in body shape and color to any object: leaf, branch, twig, stone, etc. When in danger, the moth moth caterpillar stretches out and freezes on a branch like a twig. A moth moth in a motionless state can easily be mistaken for a piece of rotten wood. Camouflage is also achieved through mimicry. Mimicry refers to similarities in color, body shape, and even behavior and habits between two or more species of organisms. For example, bumblebees and wasp flies, which lack a sting, are very similar to bumblebees and wasp flies - stinging insects.
One should not think that protective coloring necessarily and always saves animals from extermination by enemies. But organisms or groups of them that are more adapted in color die much less often than those that are less adapted.
Along with protective coloring, animals have developed many other adaptations to living conditions, expressed in their habits, instincts, and behavior. For example, in case of danger, quail quickly descend to the field and freeze in a motionless position. In deserts, snakes, lizards, and beetles hide from the heat in the sand. At the moment of danger, many animals take 16 threatening poses.
5. Classification of the subkingdom Protozoa, their structure and life activity page 35 of the textbook
Subkingdom Protozoa, or Unicellular (Protozoa)
[edit]
Type of Sarcomastigophora (Sarcomastigophora)
Subtype Sarcodae (Sarcodina)
Class Rhizomes (Rhizopoda)
Order Foraminifera (Foraminifera)
Class Rays, or Radiolarians (Radiolaria)
Solnechniki class (Heliozoa)
Subphylum Flagellates (Mastigophora), or (Flagellata)
Class Plant flagellates, Order Euglenovae (Euglenoidea)
Type Sporozoans (Sporozoa)
Type of Ciliates (Infusoria), or (Ciliata)
Subkingdom Protozoa
general characteristics
The subkingdom Protozoa includes single-celled animals; each individual has all the basic life functions: metabolism, irritability, movement, reproduction. There are also colonial species. Habitats: marine and fresh water bodies, soil, plant, animal and human organisms.
Structure. A protozoan cell is an independent organism with one or more nuclei. The cytoplasm contains both organelles characteristic of the cells of multicellular animals (mitochondria, ribosomes, Golgi complex, etc.), and organelles characteristic only of this group of animals (stigmas, trichocysts, axostyle and other organelles). The cytoplasm is bounded by an outer membrane, which can form a pellicle (an elastic and strong cell wall). The outer layer of the cytoplasm is usually lighter and denser - ectoplasm, the inner layer is endoplasm, containing various inclusions. Some protozoa have a shell above the membrane.
Nutrition heterotrophic: in some, food can come anywhere in the body, in others it comes through specialized organelles: the cellular mouth, the cellular pharynx. Digestion is intracellular using the digestive vacuole. Undigested residues are excreted either anywhere in the body, or through a special hole - powder. There are mixotrophic organisms that feed in the light through photosynthesis and have chromatophores, and in the absence of light they switch to a heterotrophic type of nutrition. Often these organisms have contractile vacuoles.
Breath. The vast majority of protozoa are aerobic organisms.
The response to environmental influences - irritability - manifests itself in the form of taxis - movements of the whole organism directed either towards the stimulus or away from it. For example, green euglena exhibits positive phototaxis - it moves towards the light. When unfavorable conditions occur, most protozoa form cysts. Encystment is a way of surviving unfavorable conditions.
Reproduction. Asexual reproduction: either the mitotic division of a vegetative individual into two daughter cells, or multiple division, which produces several daughter cells. There is a sexual process - conjugation (in ciliates) and sexual reproduction (in ciliates, Volvox, malarial plasmodium).
Manifold. There are from 30 to 70 thousand species (according to various authors).
^ Phylum Rootflagellates (Sarcomastigophora)
Rice. 96. Structure of amoeba:
1 - pseudopod; 2 - ectoplasm; 3 - endoplasm; 4 - core; 5 - phagocytosis of food; 6 - contractile vacuole; 7 - digestive vacuole.
^ Class Rhizomes, or Sarcodidae (Sarcodina)
The body shape is variable; some species form shells. Organelles of movement and food capture are pseudopods. Most species have one nucleus. There are two layers in the cytoplasm - ectoplasm (light outer layer) and endoplasm (inner granular layer). Food is captured using pseudopods. The release of undigested residues occurs in any part of the cell. When unfavorable conditions occur, they are capable of encystation. Most species reproduce asexually (mitotic cell division).
Amoeba Proteus (Fig. 96) is one of the largest free-living amoebas (up to 0.5 mm), lives in fresh water bodies.
It has long pseudopods, one nucleus, a formed cellular mouth and no powder. It moves with the help of the movement of the cytoplasm in a certain direction. Pseudophodes are formed and food is captured with their help. This process of taking up solid food particles is called phagocytosis. A digestive vacuole is formed around the captured food particle, into which enzymes enter.
Amoeba reproduces by mitotic division in half. Under unfavorable conditions, it is capable of encysting; cysts, along with dust, are transported over long distances.
A number of amoebas live in the human intestine, such as intestinal amoeba and dysenteric amoeba. Dysenteric amoeba can live in the intestines without causing harm to the host, this phenomenon is called carriage. But sometimes dysentery amoebas penetrate the intestinal mucosa and cause ulceration. As a result, amoebic dysentery develops - intestinal disorder with bloody discharge, intestinal pain (colitis). The spread of dysentery amoebas occurs through cysts; flies can be carriers.
^ Class Flagellates (Mastigophora)
Rice. 97. Structure of euglena:
1 - pellicle; 2 - reserve nutrients; 3 - core; 4 - chromatophores; 5 - contractile vacuole; 6 - stigma; 7 - flagellum.
The body shape is constant, there is a pellicle. The nucleus is usually single, but there are binucleate species, such as lamblia, and multinucleate species, such as opalina. The organelles of movement are one or more flagella. Representatives are divided into two subclasses: Plant flagellates and Animal flagellates.
Plant flagellates are capable of mixed (mixotrophic) nutrition. These include green euglena and volvox. They have one core. Asexual reproduction occurs through longitudinal mitotic cell division, sexual reproduction occurs with the formation and fusion of gametes (in Volvox).
Euglena green lives in fresh water bodies. It has one flagellum, one nucleus, and a constant body shape due to the presence of a pellicle (Fig. 97). In the front part of the cell there is a stigma (light perception organelle) and a contractile vacuole, and about twenty chromatophores are located in the cytoplasm. Euglenas are characterized by a mixotrophic mode of nutrition. Grains of reserve nutrients accumulate in the cytoplasm. There is a pharynx in the front of the body. Reproduction is only asexual, by longitudinal mitotic division.
Volvox - a colony of flagellated animals, having a spherical shape about 3 mm in size. The cells of a colony are called zooids; the number of zooids can reach 60 thousand. They are located along the periphery of the colony and are connected to each other by cytoplasmic bridges. The central part of the colony is filled with a gelatinous substance formed as a result of the mucilage of the cell walls.
There is a specialization among cells: they can be vegetative and generative. Generative zooids are associated with reproduction. In spring, generative zooids plunge into the colony and there mitotically divide, forming daughter colonies. Then the mother colony is destroyed, and the daughter colonies begin to exist independently. In autumn, macrogametes and microgametes are formed from generative zooids. Copulation of gametes occurs, the zygote overwinters, divides meiotically, and haploid zooids form a new colony.
6.the meaning of protozoa in nature and human life p.50 textbook
Protozoa are a source of food for other animals. In the seas and fresh waters, protozoa, primarily ciliates and flagellates, serve as food for small multicellular animals. Worms, mollusks, small crustaceans, as well as the fry of many fish feed primarily on single-celled organisms. These small multicellular organisms, in turn, feed on other, larger organisms. The largest animal that has ever lived on Earth, the blue whale, like all other baleen whales, feeds on very small crustaceans that inhabit the oceans. And these crustaceans feed on single-celled organisms. Ultimately, whales depend on single-celled animals and plants for their existence.
Protozoa are participants in the formation of rocks. Examining a crushed piece of ordinary writing chalk under a microscope, you can see that it consists mainly of the smallest shells of some animals. Marine protozoa (rhizopods and radiolarians) play a very important role in the formation of marine sedimentary rocks. Over many tens of millions of years, their microscopically small mineral skeletons settled to the bottom and formed thick deposits. IN In ancient geological epochs, during the mountain-building process, the seabed became dry land. Limestones, chalk and some other rocks largely consist of the remains of the skeletons of marine protozoa. Limestone has long been of great practical importance as a building material.
The study of fossil remains of protozoa plays a large role in determining the age of different layers of the earth's crust and finding oil-bearing layers.
The fight against water pollution is the most important state task. Protozoa are an indicator of the degree of pollution of fresh water bodies. Each type of protozoan animal requires certain conditions to exist. Some protozoa live only in clean water, containing a lot of dissolved air and not polluted by waste from factories and factories; others are adapted to life in water bodies of moderate pollution. Finally, there are protozoa that can live in very polluted wastewater. Thus, the presence of a certain species of protozoa in a reservoir makes it possible to judge the degree of its pollution.
So, protozoa are of great importance in nature and in human life. Some of them are not only useful, but also necessary; others, on the contrary, are dangerous.
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These animals cause diseases that are classified as vector-borne. Vector-borne diseases are diseases whose causative agent is transmitted through the bite of a blood-sucking insect or tick.
N 
Rice. 98. Ulcers caused by Leishmania and the mosquito that transmits the disease.
some types leishmania
cause cutaneous leishmaniasis (“Pendinsky ulcer”), the carriers of the pathogens are mosquitoes, the source of invasion is wild rodents or sick people (Fig. 98).
Rice. 99. Tsetse fly and sleeping sickness patient in the last stages of the disease.
Rice. 100. Life cycle
Trypanosoma rhodesiense.
^ Type Ciliates, or Ciliated (Ciliophora)
The phylum includes more than 7 thousand species of the most highly organized protozoa; let’s look at the structural features using the example of the ciliate slipper (Fig. 101). The body shape is constant thanks to the elastic and durable pellicle. They actively move with the help of cilia. Another important feature is the presence of two qualitatively different nuclei: a large polyploid vegetative nucleus - macronucleus and a small diploid generative nucleus - micronucleus. The ectoplasm of many ciliates contains special protective devices - trichocysts. When an animal is irritated, they shoot a long elastic thread that paralyzes the prey.
Nutrition. Food is captured using the cellular mouth and cellular pharynx, where food particles are directed using the beating of cilia. The pharynx opens directly into the endoplasm. Undigested residues are thrown out through the powder. Breathing occurs through the entire surface of the body.
Excess water is removed with the help of two contractile vacuoles with afferent tubules, their contents are alternately poured out through the excretory pores. Under unfavorable conditions they are capable of encystation.
B 
Rice. 101. Structure of the ciliate shoe:
1 - cytostome; 2 - cell pharynx; 3 - digestive vacuole; 4 - powder; 5 - large core (vegetative); 6 - small nucleus (generative); 7 - contractile vacuole; 8 - adducting channels of the contractile vacuole; 9 - eyelashes; 10 - digestive vacuole.
asexual reproduction - transverse mitotic division, alternating with the sexual process - conjugation and sexual reproduction. It should be remembered that sexual reproduction is accompanied by an increase in the number of individuals.
Conjugation and sexual reproduction of slipper ciliates occur under unfavorable conditions. The two ciliates are connected to each other by the perioral regions (Fig. 102), at this point the pellicle is destroyed and a cytoplasmic bridge is formed that connects both ciliates. Then the macronuclei are destroyed, the micronuclei undergo meiotic division, and four haploid nuclei are formed. Three nuclei are destroyed, the fourth divides mitotically. At this time, each ciliate has two haploid nuclei, the female (stationary) nucleus remains in place, the male one migrates along the cytoplasmic bridge to another ciliate. After this, the fusion of male and female nuclei occurs. Conjugation continues for several hours, then the ciliates disperse.
In each of the ex-conjugants, the diploid nucleus undergoes a series of mitotic divisions, the ex-conjugants themselves divide, resulting in the formation of 8 ciliates, each of which has one polyploid macronucleus and one diploid micronucleus.
Rice. 102. Reproduction of slipper ciliates:
1 - conjugation; 2 - destruction of macronuclei, meiosis of micronuclei; 3 - destruction of micronuclei; 4 - exchange of male nuclei; 5 - fusion of male and female nuclei; 6 - three mitotic divisions, the formation of four micronuclei and four macronuclei; 7 - destruction of three micronuclei; 8 - division of each ciliate into two individuals with two macronuclei and a micronucleus; 9 - formation of eight individuals.
Thus, two individuals took part in conjugation, and reproduction ended with the formation of eight individuals.
^ Phylum Sporozoa
M 
Rice. 103. Life cycle of malarial plasmodium:
1 - penetration of sporozoites into the human body; 2-4 - schizogony in liver cells; 5-10 - erythrocyte schizogony; 11-16 - formation of gamonts; 17-18 gametes in the stomach of a mosquito; 19-22 - copulation of gametes, formation of ookinetes; 23-25 oocyst formation and sporogony; 26 - migration of sporozoites into the salivary glands of the mosquito.
Plasmodium alaria causes malaria in humans. Infection occurs through the bite of a malaria mosquito (genus Anopheles), which contains the pathogen at the sporozoite stage (Fig. 103).
Sporozoites are thin, worm-shaped cells that enter the liver cells through the bloodstream, where they turn into schizonts, which reproduce by multiple divisions - schizogony. In this case, the nucleus divides repeatedly, then a large number of daughter cells are formed from each cell. The resulting merozoites leave the liver cells and invade the red blood cells. Here they feed, then schizogony occurs again. Thus, two forms of schizogony are distinguished - in liver cells and in erythrocytes.
As a result of erythrocyte schizogony, 10-20 merozoites are formed, which destroy the erythrocyte, enter the blood and infect subsequent erythrocytes. The cyclical nature of malaria attacks is due to the cyclical release of merozoites and their metabolic products from erythrocytes into the blood plasma. After several cycles of schizogony, gamonts are formed in erythrocytes, which in the mosquito’s body will turn into macrogametes and microgametes. When gamonts enter the stomach of a mosquito, they turn into gametes, copulation occurs, the fusion of gametes. The zygote is mobile and is called an ookinete. The ookinete migrates through the mosquito's stomach wall and develops into an oocyst. The oocyst nucleus divides many times, and the oocyst breaks up into a huge number of sporozoites - up to 10,000. This process is called sporogony. Sporozoites migrate to the salivary glands of the mosquito. Meiosis occurs after the formation of the zygote, sporozoites are haploid.
Thus, in the life cycle of Plasmodium falciparum, humans are the intermediate host (pre-erythrocytic schizogony, erythrocyte schizogony, onset of gametogony), and the malarial mosquito is the final host (completion of gametogony, fertilization and sporogony).
7.- 8 Type Coelenterates. Structure and activity pp.54-55
Coelenterates- one of the oldest groups of multicellular animals, numbering 9000 thousand species. These animals lead an aquatic lifestyle and are common in all seas and freshwater bodies. Descended from colonial protozoa - flagellates. Coelenterates lead a free or sedentary lifestyle. The phylum Coelenterata is divided into three classes: Hydroid, Scyphoid and Coral polyps.
The most important general characteristic of coelenterates is their two-layer body structure. It consists of ectoderm And endoderm , between which there is a non-cellular structure - mesoglea. These animals got their name because they have intestinal cavity in which food is digested.
Basic aromorphoses, which contributed to the emergence of coelenterates, are the following:
– the emergence of multicellularity as a result of specialization and association;
– cells interacting with each other;
– the appearance of a two-layer structure;
– the occurrence of cavity digestion;
– the appearance of body parts differentiated by function; the appearance of radial or radial symmetry.
Hydroid class. Representative - freshwater hydra.
Hydra is a polyp, about 1 cm in size. It lives in freshwater bodies. It is attached to the substrate by the sole. The front end of the body forms a mouth surrounded by tentacles. Outer layer of the body - ectoderm consists of several types of cells differentiated by their functions:
– epithelial-muscular, ensuring the movement of the animal;
– intermediate, giving rise to all cells;
– stinging insects that perform a protective function;
– sexual, ensuring the process of reproduction;
– nerves, united into a single network and forming the first nervous system in the organic world.
Endoderm consists of: epithelial-muscular, digestive cells and glandular cells that secrete digestive juice.
Hydra, like other coelenterates, has both intracellular and intracellular digestion. Hydras are predators that feed on small crustaceans and fish fry. Breathing and excretion in hydras is carried out over the entire surface of the body.
Irritability manifests itself in the form of motor reflexes. The tentacles react most clearly to irritation, because Nerve and epithelial-muscle cells are most densely concentrated in them.
Reproduction occurs budding And sexually. The sexual process occurs in the fall. Some intermediate cells ectoderms turn into germ cells. Fertilization occurs in water. In the spring, new hydras appear. Among the coelenterates there are hermaphrodites and dioecious animals.
Many coelenterates are characterized by alternating generations. For example, jellyfish are formed from polyps. Larvae develop from fertilized jellyfish eggs - planulae. The larvae develop into polyps again.
Hydras are able to restore lost body parts due to the reproduction and differentiation of nonspecific cells. This phenomenon is called regeneration.
Class Scyphoid. Combines large jellyfish. Representatives: Kornerot, Aurelia, Cyanea.
Jellyfish live in the seas. The body resembles an umbrella in shape and consists mainly of gelatinous mesoglea, covered on the outside with a layer of ectoderm, and on the inside with a layer of endoderm. Along the edges of the umbrella there are tentacles surrounding the mouth, located on the underside. The mouth leads into the gastric cavity, from which radial canals extend. The channels are connected to each other by a ring channel. As a result, gastric system.
The nervous system of jellyfish is more complex than that of hydras. In addition to the general network of nerve cells, along the edge of the umbrella there are clusters of nerve ganglia, forming a continuous nerve ring and special balance organs - statocysts. Some jellyfish develop light-sensitive eyes and sensory and pigment cells corresponding to the retina of higher animals.
In the life cycle of jellyfish, sexual and asexual generations naturally alternate. They are dioecious. The gonads are located in the endoderm under the radial canals or on the oral stalk. Reproductive products exit through the mouth into the sea. A free-living larva develops from the zygote. planula. The planula turns into a small polyp in the spring. Polyps form groups similar to colonies. Gradually they disperse and turn into adult jellyfish.
Class Coral polyps. Includes solitary (anemones, brain sea anemones) or colonial forms (red coral). They have a calcareous or silicon skeleton formed by needle-shaped crystals. They live in tropical seas. Clusters of coral polyps form coral reefs. They reproduce asexually and sexually. Coral polyps do not have a jellyfish stage of development.
