Features of the structure of prokaryotes and eukaryotes presentation. Prokaryotes and eukaryotes - presentation. V. Learning new material

consider the features of the structure and function of non-membrane and two-membrane organelles.

Characterization of bacteria

Distributed everywhere: in water, soil, air, living organisms. They are found both in the deepest oceanic depressions and on the highest mountain peak of the Earth - Everest, both in the ice of the Arctic and Antarctica, and in hot springs. In the soil, they penetrate to a depth of 4 km or more, bacterial spores in the atmosphere are found at an altitude of up to 20 km, the hydrosphere has no boundaries at all for these organisms.

Bacteria are able to settle on almost any organic or inorganic substrate.

Despite their simple structure, they have a high degree of adaptability to a wide variety of environmental conditions. This is possible due to the ability of bacteria to rapidly change generations. With an abrupt change in the conditions of existence, mutant forms rapidly appear among bacteria that can exist in new environmental conditions.

Sizes from 1 to 15 microns. By the shape of the cells are distinguished: Spherical - cocci:

micrococci - are divided in different planes, lie singly;

diplococci

tetracocci

streptococci -

staphylococci -

sarcins -

diplococci - are divided in one plane, form pairs; tetracocci - are divided in two planes, form tetrads; streptococci - are divided in one plane, form chains; staphylococci - divide in different planes, form clusters resembling bunches of grapes; sarcins - are divided in three planes, form packs of 8 individuals.

Elongated - bacilli (rod-shaped) - are divided in different planes, lie alone;

Crimped - vibrios (in the form of a comma); spirilla - have from 4 to 6 turns; spirochetes - long and thin convoluted shapes with the number of turns from 6 to 15.

In addition to the main ones, other, very diverse, forms of bacterial cells are found in nature.

Cell wall

The bacterial cell is enclosed in a dense, rigid cell wall, which accounts for 5 to 50% of the dry mass of the cell.

The cell wall acts as an external barrier of the cell, establishing contact between the microorganism and the environment.

The main component of the bacterial cell wall is a polysaccharide - murein. According to the content of murein, all bacteria are divided into two groups: gram-positive and gram-negative.

In many bacteria, a mucous matrix is \u200b\u200blocated on top of the cell wall - a capsule. The capsules are formed by polysaccharides. Sometimes the capsule contains polypeptides. As a rule, the capsule performs a protective function, protecting the cell from adverse environmental factors. In addition, it can facilitate attachment to the substrate and participate in locomotion.

The cytoplasmic membrane regulates the flow of nutrients into the cell and the release of metabolic products outside.

Usually, the growth rate of the cytoplasmic membrane outstrips the growth rate of the cell wall. This leads to the fact that the membrane often forms numerous invaginations (invaginations) various shapes - mesosomes .

The mesosomes associated with the nucleoid play a role in DNA replication and subsequent chromosome separation.

Probably, mesosomes provide cell division into separate isolated compartments, thereby creating favorable conditions for enzymatic processes.

In the cells of photosynthetic bacteria there are intracytoplasmic membrane formations - chromatophores ensuring the course of bacterial photosynthesis.

Bacteria are characterized by 70 S ribosomes formed by two subunits: 30 S and 50 S. Ribosomes of bacterial cells are assembled into polysomes formed by tens of ribosomes.

Bacterial cells can have a variety of cytoplasmic inclusions - gas vacuoles, vesicles containing bacteriochlorophyll, polysaccharides, sulfur deposits, and others.

Nucleoid. Bacteria do not have a structurally formed nucleus. The genetic apparatus of bacteria is called nucleoid ... It is a DNA molecule concentrated in a limited space of the cytoplasm.

The DNA molecule has a typical structure. It consists of two polynucleotide chains that form a double helix. Unlike eukaryotes, DNA is circular, rather than linear.

The bacterial DNA molecule is identified with one eukaryotic chromosome. But if in eukaryotes in chromosomes DNA is associated with proteins, then in bacteria DNA does not form complexes with proteins.

The bacterial DNA is attached to the cytoplasmic membrane in the mesosome region.

The cells of many bacteria have non-chromosomal genetic elements - plasmids ... They are small circular DNA molecules capable of replicating independently of chromosomal DNA. Among them there are F -factor - a plasmid that controls the sexual process.

Flagella. There are many mobile forms among bacteria. Flagella play the main role in movement.

Bacterial flagella are only superficially similar to eukaryotic flagella, but their structure is different. They have a smaller diameter and are not surrounded by a cytoplasmic membrane. The filament of the flagellum consists of 3-11 helically twisted fibrils formed by the flagellin protein.

At the base there is a hook and paired discs that connect the filament with the cytoplasmic membrane and cell wall. Flagella move, rotating in the membrane. The number and location of flagella on the cell surface can vary.

Fimbria are thin filamentous structures on the surface of bacterial cells, which are short, straight, hollow cylinders formed by the pilin protein. Thanks to the fimbria, bacteria can attach to the substrate or adhere to each other. Special fimbria - genital fimbria , or F -drank - provide the exchange of genetic material between cells.

Physiology of bacteria. Nutrition

Meals

Heterotrophs

Autotrophs

Saprotrophs

Photoautotrophs

Chemoautotrophs

Symbionts

Physiology of bacteria. Nutrition

Nutrition of bacteria.

Together with food, bacteria, like other organisms, receive energy for vital processes and construction material for the synthesis of cellular structures.

Bacteria are distinguished:

heterotrophs consuming ready-made organic matter. They can be:

saprotrophs , that is, feed on dead organic matter;

Physiology of bacteria. Nutrition

Another group, autotrophs capable of synthesizing organic matter from inorganic. Among them are distinguished:

photoautotrophs, chemoautotrophs

photoautotrophs, synthesizing organic substances due to the energy of light, and chemoautotrophs synthesizing organic substances due to the chemical energy of oxidation of inorganic substances: sulfur, hydrogen sulfide, ammonia, etc. These include nitrifying bacteria, iron bacteria, hydrogen bacteria, etc.

Photoautotrophs:

Photosynthetic sulfur bacteria (green and purple) They have photosystem-1 and do not emit oxygen during photosynthesis, the hydrogen donor is Н 2 S:

6CO 2 + 12H 2 S → FROM 6 H 12 ABOUT 6 + 12 S + 6H 2 ABOUT

In cyanobacteria (blue-green) photosystem-2 appeared and during photosynthesis oxygen is released, the donor of hydrogen for the synthesis of organic matter is Н 2 О:

6CO 2 + 12H 2 ABOUT → FROM 6 H 12 ABOUT 6 + 6O 2 + 6H 2 ABOUT

Physiology of bacteria

Chemoautotrophs :

Chemosynthetics oxidize ammonia (nitrifying bacteria) hydrogen sulfide, sulfur, hydrogen and iron compounds. The source of hydrogen for the reduction of carbon dioxide is water. Discovered in 1887 by S.N. Vinogradsky.

The most important group of chemosynthetics is nitrifying bacteria capable of oxidizing ammonia formed during the decay of organic residues, first to nitrogenous, and then to nitric acid:

2 NH 3 + 3O 2 \u003d 2HNO 2 + 2H 2 O + 663 kj

2H N ABOUT 2 + O 2 \u003d 2HNO 3 + 142 kj

Nitric acid, reacting with mineral compounds of the soil, forms nitrates, which are well absorbed by plants.

Physiology of bacteria

Chemoautotrophs:

Colorless sulfur bacteria oxidize hydrogen sulfide and accumulate sulfur in their cells:

2H 2 S + O 2 \u003d 2H 2 O + 2 S + 272 kJ

With a lack of hydrogen sulphide, bacteria produce further oxidation of sulfur to sulfuric acid:

2 S + 3O 2 + 2H 2 O \u003d 2H 2 S ABOUT 4 + 636 kj

Iron bacteria oxidize bivalent iron to trivalent:

4 FeCO 3 + O 2 + H 2 O \u003d 4Fe (OH) 3 + 4CO 2 + 324 kj

Hydrogen bacteria use the energy released during the oxidation of molecular hydrogen:

2H 2 + O 2 \u003d 2H 2 O + 235 kJ

Physiology of bacteria. Reproduction

The bacteria are capable of intensive reproduction. Sexual reproduction in bacteria is absent, only asexual reproduction is known. Some bacteria can divide every 20 minutes under favorable conditions.

Asexual reproduction

Asexual reproduction is the main way bacteria reproduce. It can be done by binary fission and budding.

Most bacteria reproduce by binary equal-size transverse cell division. In this case, two identical daughter cells are formed. DNA replication takes place before division.

Budding. Some bacteria multiply by budding. In this case, a short outgrowth forms at one of the poles of the mother cell - hypha , at the end of which a kidney is formed, one of the shared nucleoids passes into it. The kidney grows, turning into a daughter cell, and is separated from the mother as a result of the formation of a septum between the kidney and the hyphae.

The sexual process, or genetic recombination.

Sexual reproduction is absent, but the sexual process is known. Bacteria do not form gametes, there is no cell fusion, but the main event of the sexual process occurs - the exchange of genetic information. This process is called genetic recombination ... Part of the DNA (less often all) by the donor cell transfers to the recipient cell and replaces part of the DNA of the recipient cell. The resulting DNA is called recombinant ... It contains the genes of both parental cells.

There are three ways of genetic recombination: conjugation, transduction, transformation;

Conjugation is a direct transfer of a piece of DNA from one cell to another during direct contact of cells with each other. The donor cell forms what is called an F-pill, its formation is controlled by a special plasmid - F-plasmid ... During conjugation, DNA is transferred in only one direction (from donor to recipient), there is no reverse transfer.

Transduction is the transfer of DNA fragments from one bacterium to another using bacteriophages.

The importance of bacteria

Bacteria play a huge role in the biosphere and in human life. Bacteria take part in many biological processes, especially in the cycle of substances in nature. Significance for the biosphere:

Putrefactive bacteria destroy nitrogen-containing organic compounds of inanimate organisms, turning them into humus.

Mineralizing bacteria decompose complex organic compounds of humus to simple inorganic substances, making them available to plants.

Many bacteria can fix atmospheric nitrogen. Moreover, azotobacter free-living in soil fixes nitrogen independently of plants, and nodule bacteria show their activity only in symbiosis with the roots of higher plants (mainly legumes), thanks to these bacteria, the soil is enriched with nitrogen and the productivity of plants increases.

The importance of bacteria

Symbiotic bacteria intestines of animals (primarily herbivores) and humans ensure the assimilation of fiber, form vitamins (B 12, K).

Bacteria also play a significant role in soil formation. (destruction of minerals of parent rocks, formation of humus).

The importance of bacteria

Meaning for a person:

Obtaining lactic acid products for sauerkraut, forage ensiling;
For the production of organic acids, alcohols, acetone, enzymatic preparations;

The importance of bacteria

They are actively used as producers of many biologically active substances (antibiotics, amino acids, vitamins, etc.) used in medicine, veterinary medicine and animal husbandry;
Thanks to the methods of genetic engineering, with the help of bacteria, such necessary substances as human insulin and interferon are obtained;

The importance of bacteria

Human uses bacteria and for cleaning wastewater.
A negative role is played by pathogenic bacteria that cause diseases of plants, animals and humans.
Many bacteria cause food spoilage, releasing toxic substances.

Reiteration:

Continue sentences:

Genetic material in prokaryotes is represented by (_).
Ribosomes of prokaryotes differ from eukaryotic ones (_).
Of the one-membrane organelles, prokaryotes lack: EPS? Golgi complex? Lysosomes? Vacuoles?
Prokaryotes lack two membrane organelles: Nucleus? Mitochondria? Plastids?
Prokaryotes reproduce (_).
With respect to oxygen, bacteria are divided into (_).
Heterotrophic organisms - (_).
Autotrophic organisms - (_).

Prokaryotes and eukaryotes Prepared by: 8B grade student Roman Persov OU "Lyceum boarding school for gifted children named after academician PA Kirpichnikov with in-depth study of chemistry" FSBEI HPE "KNITU"

Foreword All organisms with a cellular structure are divided into two groups: prenuclear (prokaryotes) and nuclear (eukaryotes). The cells of prokaryotes, which include bacteria, in contrast to eukaryotes, have a relatively simple structure. In a prokaryotic cell there is no organized nucleus, it contains only one chromosome, which is not separated from the rest of the cell by a membrane, but lies directly in the cytoplasm. However, it also contains all the hereditary information of the bacterial cell.

The cytoplasm of prokaryotes is much poorer in structure composition than that of eukaryotic cells. There are numerous smaller ribosomes than in eukaryotic cells. The functional role of mitochondria and chloroplasts in prokaryotic cells is played by special, rather simply organized membrane folds.

Comparative characteristics of eukaryotic cells Comparative characteristics of eukaryotic cells. Structurally, various eukaryotic cells are similar. But along with the similarities between the cells of organisms of different kingdoms of living nature, there are noticeable differences. They relate to both structural and biochemical features.

A plant cell is characterized by the presence of various plastids, a large central vacuole, which sometimes pushes the nucleus to the periphery, as well as a cell wall located outside the plasma membrane of the cell wall, consisting of cellulose. In the cells of higher plants in the cell center there is no centriole, which is found only in algae. The reserve nutritional carbohydrate in plant cells is starch.

In the cells of representatives of the kingdom of fungi, the cell wall usually consists of chitin - a substance from which the outer skeleton of arthropods is built. There is a central vacuole, no plastids. Only a few fungi have a centriole in the cell center. The storage carbohydrate in fungal cells is glycogen.

Source ... Textbook: "General Biology" for Cl. educational institutions. "General biology" for cl. educational institutions. html% 2Fimg% 2F2cb6hwn_vgsnp2rn% 2Fjpeg% 2F100x100% 2FFunctional- classification.jpeg & pos \u003d 16 & rpt \u003d simage & _ \u003d

Prokaryotes and eukaryotes. In modern and fossil organisms, two types of cells are known: prokaryotic and eukaryotic. These cells differ so much in their structural features that two super kingdoms were distinguished - prokaryotes (prenuclear) and eukaryotes (real nuclear). The intermediate forms between these largest living taxa are still unknown. The main difference between a prokaryotic cell and a eukaryotic cell is that their DNA is not organized into chromosomes and is not surrounded by a nuclear envelope. Eukaryotic cells are much more complex. Their DNA, associated with a protein, is organized into chromosomes, which are located in a special formation, in fact, the largest cell organelle - the nucleus. In addition, the extra-nuclear active content of such a cell is divided into separate compartments using the endoplasmic reticulum. EPS is formed by the simplest membrane. Eukaryotic cells are usually larger than prokaryotic cells.

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Cell

"Mitosis cell division" - Prophase Metaphase Anaphase telophase. Metaphase. Anaphase. Interphase. DNA spiralization occurs in the nucleus; The nucleoli disappear. Formation of a fission spindle, shortening of chromosomes, formation of an equatorial plate. Then mitosis (cell division) occurs, and the cycle repeats again. Mitosis disorders. Telophase.

“Cell of an organism” - The prokaryotic type of cellular organization preceded the eukaryotic type of cellular organization. 1. Introduction. Hypothesis. What explains the variety of types of cell structure? 3 Comparison of plant and animal cells. Working group: Kobets V., Dedova A., Fokina A., Nechaev S., Tsvetkov V., Datskevich Yu.

"Cell in the body" - The cells of most Single-celled organisms contain all the parts of eukaryotic cells. Microscopes have been continuously improved. Cell classification. Cells of multicellular animals. Somatic cells Sex cells. Control questions... What are the components of a cell? What cells do you know?

"Cell division" - Meiosis Greek "meiosis" - decrease. Late prophase. Mitosis. Mitotic cycle. Chromosomes are concentrated at opposite poles of the cell. Mitosis Greek "mitos" - thread. Biological meaning. Types of cell division. Somatic. Anaphase. Metaphase. Amitosis. Telophase. Early prophase. Genital.

"Meiosis" - Gametes with a haploid set arise from the original cells with a diploid set of chromosomes. Spermatogenesis. The second division of meiosis leads to the formation of second-order haploid spermatocytes. The first division of meiosis. The reproduction and individual development of organisms is based on the process of cell division.

Prokaryotic cell

Bacteria are the "great gravediggers of nature" Louis Pasteur. These small organisms created life on Earth, make the global cycle of substances in nature, and also serve humans.

Properties Species of prokaryotes 1. Origin 2. Habitat and prevalence 3. Size 4. Shape 5. Structure of bacterial cells 6. Metabolism, relation to oxygen 7. Nutrition 8. Reproduction 9. Spore formation 10. Role in nature 11. Human use

Origin of prokaryotes Originally appeared in an oxygen-free environment 2.5-3 billion years ago in the seas

Habitat of prokaryotes Atmosphere Hydrosphere Lithosphere Inside cells

Sizes Sizes of bacterial cells range from 1 to 10-15 microns

Form of Cocci Diplococci Tetracocci

Streptococcus form

Shape of Sarcinia Staphylococcus Rods (bacilli)

Spirilla's shape Spirochete Vibrio

The structure of the bacterial cell On the surface of bacteria, various kinds of flagella (pili) and villi (fimbia) are often visible - organelles of movement, with the help of which they move by sliding.

The structure of a bacterial cell 1 - cell wall, 2 - outer cytoplasmic membrane, 3 - chromosome (circular DNA molecule), 4 - invagination of the outer cytoplasmic membrane, 5 - vacuoles, 6 - mesosome (outgrowth of the outer membrane), 7 - stacks of membranes in which photosynthesis is carried out, 8 - ribosome, 9 - flagella.

The structure of a bacterial cell The cell wall of prokaryotes is rigid, contains polysaccharides and amino acids. The main strengthening component is murein. The cell wall of many bacteria is covered with a layer of mucus on top. The cytoplasm is surrounded by a membrane that separates it from the inside from the cell wall.

The structure of a bacterial cell The main feature is the absence of a nucleus bounded by a membrane. Hereditary information in bacteria is contained in one chromosome. Free ribosomes are smaller than in eukaryotes; they carry out protein biosynthesis

Metabolism In relation to oxygen, prokaryotes are divided into two groups: anaerobic (not requiring oxygen); aerobic, (living in an oxygen environment); some bacteria can live in both oxygen-free and oxygenated environments

Reproduction Bacteria have two methods of reproduction: by dividing the cell in two and sexually

Sporulation Many bacteria are characterized by sporulation. Disputes arise when there is a lack of nutrients or when metabolic products accumulate in the environment, i.e. unfavorable conditions arise

Role in nature A) Bacteria destroy the remains of organic matter, produce mineralization. B) Bacteria - symbionts (Escherichia coli), settling in digestive tract in animals, they break down cellulose to glucose, and ensures the absorption of these substances by the animal body, produce vitamins and other substances. C) Nitrogen-fixing (nodule) bacteria promote the assimilation of soil nitrogen by plant roots.

Human use Obtaining many food and technical products is impossible without the participation of various fermentative bacteria (in Fig. Bifidobacteria)

The negative role of bacteria Different kinds putrefactive bacteria cause spoilage food products... Salmonellosis, botulism, cholera dysentery, are diseases associated with the consumption of spoiled food. Whooping cough, tuberculosis, plague, sexually transmitted diseases, tetanus, pneumonia and many others are transmitted by airborne droplets or sexually.

Why did Louis Pasteur call prokaryotic organisms the great gravediggers in nature?

How do you feel while studying this topic?

Characteristics of bacteria Distributed everywhere: in water, soil, air, living organisms. They are found both in the deepest oceanic depressions and on the highest mountain peak of the Earth Everest, both in the ice of the Arctic and Antarctica, and in hot springs. In the soil, they penetrate to a depth of 4 km or more, bacterial spores in the atmosphere are found at an altitude of up to 20 km, the hydrosphere has no boundaries at all for these organisms. Bacteria are able to settle on almost any organic or inorganic substrate. Despite their simple structure, they have a high degree of adaptability to a wide variety of environmental conditions. This is possible due to the ability of bacteria to rapidly change generations. With an abrupt change in the conditions of existence, mutant forms rapidly appear among bacteria that can exist in new environmental conditions.

Sizes from 1 to 15 microns. The cells are distinguished by the shape of the cells: Spherical cocci: micrococci divide in different planes, lie alone; diplococci are divided in one plane, form pairs; tetracocci are divided in two planes, form tetrads; streptococci are divided in one plane, form chains; staphylococci divide in different planes, form clusters that resemble bunches of grapes; sarcins are divided in three planes, form packets of 8 individuals. Characterization of bacteria

Elongated bacilli (rod-shaped) are divided in different planes, lie alone; Twisted - vibrios (in the form of a comma); spirillae have 4 to 6 turns; spirochetes are long and thin convoluted forms with the number of turns from 6 to 15. In addition to the main ones, other, very diverse forms of bacterial cells are found in nature. Characterization of bacteria

Cell wall. The bacterial cell is enclosed in a dense, rigid cell wall, which accounts for 5 to 50% of the dry mass of the cell. The cell wall acts as an external barrier of the cell, establishing contact between the microorganism and the environment. The main component of the bacterial cell wall is the polysaccharide murein. According to the content of murein, all bacteria are divided into two groups: gram-positive and gram-negative. Characterization of bacteria

In many bacteria, a slimy matrix capsule is located on top of the cell wall. The capsules are formed by polysaccharides. Sometimes polypeptides are included in the capsule. As a rule, the capsule performs a protective function, protecting the cell from adverse environmental factors. In addition, it can facilitate attachment to the substrate and participate in locomotion. Characterization of bacteria

The cytoplasmic membrane regulates the flow of nutrients into the cell and the release of metabolic products outside. Usually, the growth rate of the cytoplasmic membrane outstrips the growth rate of the cell wall. This leads to the fact that the membrane often forms numerous invaginations (invaginations) of various forms of the mesosome. Characterization of bacteria

The mesosomes associated with the nucleoid play a role in DNA replication and subsequent chromosome separation. Probably, mesosomes provide cell division into separate isolated compartments, thereby creating favorable conditions for enzymatic processes. Characterization of bacteria

Bacterial cells can have a variety of cytoplasmic inclusions, gas bubbles, bubbles containing bacteriochlorophyll, polysaccharides, sulfur deposits, and others. Nucleoid. Bacteria do not have a structurally formed nucleus. The genetic apparatus of bacteria is called the nucleoid. It is a DNA molecule concentrated in a limited space of the cytoplasm. Characterization of bacteria

The DNA molecule has a typical structure. It consists of two polynucleotide chains that form a double helix. Unlike eukaryotes, DNA is circular, rather than linear. The bacterial DNA molecule is identified with one eukaryotic chromosome. But if in eukaryotes in the chromosomes DNA is associated with proteins, then in bacteria DNA does not form complexes with proteins. The bacterial DNA is attached to the cytoplasmic membrane in the mesosome region. Characterization of bacteria

The cells of many bacteria have nonchromosomal plasmid genetic elements. They are small circular DNA molecules capable of replicating independently of chromosomal DNA. Among them, the F-factor is a plasmid that controls the sexual process. Flagella. There are many mobile forms among bacteria. Flagella play the main role in movement. The flagella of bacteria are only superficially similar to the flagella of eukaryotes, but their structure is different. They have a smaller diameter and are not surrounded by a cytoplasmic membrane. The filament of the flagellum consists of 3-11 helically twisted fibrils formed by the flagellin protein. Characterization of bacteria

At the base there is a hook and paired discs connecting the filament with the cytoplasmic membrane and the cell wall. Flagella move, rotating in the membrane. The number and location of flagella on the cell surface can vary. Fimbriae are thin filamentous structures on the surface of bacterial cells, which are short, straight, hollow cylinders formed by the protein pilin. Thanks to the fimbria, bacteria can attach to the substrate or adhere to each other. Special fimbriae, sex fimbria, or F-pili, provide for the exchange of genetic material between cells. Characterization of bacteria

When unfavorable conditions occur, endospores are formed in gram-positive bacteria. In this case, the cell is dehydrated, the nucleoid is concentrated in the sporogenic zone. Protective shells are formed that protect bacterial spores from unfavorable conditions (spores of many bacteria can withstand heating up to 130 ° C and remain viable for decades). When favorable conditions occur, the spore germinates and a vegetative cell is formed. Characterization of bacteria

To summarize: What is known about the shape of bacteria? Cocci (diplococci, tetracocci, streptococci, sarcins, staphylococci), bacilli, vibrios, spirilla, spirochetes). What are the sizes of bacteria? 1 to 15 microns (μm). How does the bacterial cell membrane work? Plasmalemma and cell wall from murein. Gram-negative ones have two membranes. How is the genetic material of bacteria organized? Nucleoid - circular DNA and plasmids. What organelles are there in bacterial cells? Mesosomes, chlorosomes, 70-S ribosomes, flagella. How is the flagellum of bacteria different from the flagellum of eukaryotes? Not covered with a membrane, consists of several flagellin fibillae twisted together. Can bacteria grow in spores? No controversy - a way of experiencing adverse conditions.

Olympiads! Spore-forming aerobic bacteria in which the spore size does not exceed the cell diameter are called bacilli. Spore-forming anaerobic bacteria in which the size of the spore exceeds the diameter of the cell, and therefore they take the form of a spindle and are called clostridia (from the Latin Clostridium - spindle). Characterization of bacteria

Olympiads! Rickettsiae are small, gram-negative rod-shaped bacteria up to 1 micron in size. Arthropods are their hosts and carriers. In humans, typhus, tick-borne rickettsiosis, and Rocky Mountain spotted fever are caused. Mycoplasmas are small bacteria that do not have a cell wall, surrounded only by a cytoplasmic membrane. Osmotically sensitive, in humans they cause a disease like a respiratory infection. Actinomycetes - (radiant fungi), occupy an intermediate position between bacteria and fungi. Branching gram-positive bacteria. In the affected tissues, a mycelium is formed from tightly intertwined filaments (hyphae) in the form of rays extending from the center and ending in flask-shaped thickenings. Spores can form on aerial hyphae, which serve for reproduction.

Another group, autotrophs, is capable of synthesizing organic substances from inorganic ones. Among them are distinguished: photoautotrophs, synthesizing organic substances due to the energy of light, and chemoautotrophs, synthesizing organic substances due to the chemical energy of oxidation of inorganic substances: sulfur, hydrogen sulfide, ammonia, etc. These include nitrifying bacteria, iron bacteria, hydrogen bacteria, etc. Photoautotrophs: Photosynthetic sulfur bacteria (green and purple) Have photosystem-1 and do not emit oxygen during photosynthesis, hydrogen donor - Н 2 S: 6СО Н 2 S С 6 Н 12 О S + 6Н 2 О Cyanobacteria (blue-green) have photosystem-2 and during photosynthesis oxygen is released, the donor of hydrogen for the synthesis of organic matter is Н 2 О: 6СО Н 2 О С 6 Н 12 О 6 + 6О 2 + 6Н 2 О Physiology of bacteria

Chemoautotrophs: Chemoautotrophs use the energy of chemical bonds. Discovered in 1887 by S.N. Vinogradsky. The most important group of chemoautotrophs is nitrifying bacteria capable of oxidizing ammonia formed during the decay of organic residues, first to nitrous acid and then to nitric acid: 2NH 3 + 3O 2 \u003d 2HNO 2 + 2H 2 O kJ 2HNO 2 + O 2 \u003d 2HNO kJ Colorless sulfur bacteria oxidize hydrogen sulfide and accumulate sulfur in their cells: 2H 2 S + O 2 \u003d 2H 2 O + 2S kJ With a lack of hydrogen sulfide, bacteria further oxidize sulfur to sulfuric acid: 2S + 3O 2 + 2H 2 O \u003d 2H 2 SO kJ Iron bacteria oxidize bivalent iron to trivalent: 4FeCO 3 + O 2 + H 2 O \u003d 4Fe (OH) 3 + 4CO kJ Hydrogen bacteria use the energy released during the oxidation of molecular hydrogen: 2H 2 + O 2 \u003d 2H 2 O kJ Physiology of bacteria

Reproduction of bacteria. The bacteria are capable of intensive reproduction. Sexual reproduction in bacteria is absent, only asexual reproduction is known. Some bacteria can divide every 20 minutes under favorable conditions. Asexual reproduction Asexual reproduction is the main mode of reproduction of bacteria. It can be done by binary fission and budding. Most bacteria reproduce by binary equal-size transverse cell division. In this case, two identical daughter cells are formed. DNA replication takes place before division. Budding. Some bacteria multiply by budding. At the same time, a short hyphal outgrowth is formed at one of the poles of the mother cell, at the end of which a kidney is formed, one of the divided nucleoids passes into it. The kidney grows, turning into a daughter cell, and is separated from the mother as a result of the formation of a septum between the kidney and the hyphae. Physiology of bacteria

The sexual process, or genetic recombination. Sexual reproduction is absent, but the sexual process is known. Gametes are not formed in bacteria, there is no cell fusion, but the main event of the sexual process is the exchange of genetic information. This process is called genetic recombination. Part of the DNA (less often all) by the donor cell transfers to the recipient cell and replaces part of the DNA of the recipient cell. The resulting DNA is called recombinant. It contains the genes of both parental cells. Physiology of bacteria

There are three ways of genetic recombination: conjugation, transduction, transformation; Conjugation is the direct transfer of a piece of DNA from one cell to another during direct cell contact with each other. The donor cell forms the called F-pill, its formation is controlled by a special plasmid F-plasmid. During conjugation, DNA is transferred in only one direction (from donor to recipient), there is no reverse transfer. Physiology of bacteria

Participation in the cycle of chemical elements (nitrogen, carbon, oxygen, etc.). Groups of bacteria that take part in the nitrogen cycle Nitrogen-fixing bacteria Use of free nitrogen for the formation of compounds available to other organisms Enrichment of soil with nitrogen compounds Ammonifying bacteria Decomposition of nitrogen-containing substances (proteins, nucleic acids) with the formation of ammonia Mineralization Nitrifying bacteria Oxidation of ammonia salts into nitrites, then into nitrates Mineralization Denitrifying bacteria Reduction of nitrites and nitrates to free nitrogen Mineralization Importance of bacteria Destruction of organic residues. Participation in soil formation. Participation in the education of the atmosphere. Use in food Industry for obtaining lactic acid products Obtaining antibiotics, amino acids, vitamins, etc. Wastewater treatment, formation of methane Symbionts of many organisms (E. coli in humans) Cause infectious diseases (tuberculosis, tonsillitis) Currently, using transformed E. coli, insulin is obtained, somatotropic hormone, interferon The value of bacteria

The importance of bacteria Steps: Restriction (cutting of human DNA and plasmids with restriction enzymes) Creation of a vector containing all control genes (regulator, operator, marker genes) Ligation ("insertion" of a human DNA fragment into plasmids with ligases) Transformation (introduction of recombinant plasmids into bacterial cells) Screening (selection of such transformed bacteria that carry the gene necessary for a person) Reproduction of precisely those transformed bacteria that carry the gene necessary for a person.

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