Prokaryotes presentation. Lesson summary and presentation on biology on the topic "cells of prokaryotes and eukaryotes". IV. Communication of the topic and objectives of the lesson

Characteristics of bacteria Distributed everywhere: in water, soil, air, living organisms. They are found both in the deepest oceanic trenches 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 capable of settling on almost any organic or inorganic substrate. Despite the simplicity of their structure, they are highly adaptable to a wide variety of environmental conditions. This is possible due to the ability of bacteria to quickly change generations. With a sharp 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 divide in different planes, lie alone; diplococci are divided in one plane, form pairs; tetracocci are divided in two planes, form tetrads; streptococci divide in one plane, form chains; staphylococci are divided 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 singly; 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 of the microorganism with 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 the action of unfavorable 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 shapes mesosomes. 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 forming 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. 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 cell wall. Flagella move, rotating in the membrane. The number and location of flagella on the cell surface can be different. 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 fimbriae, 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 sporogenous zone. Protective shells are formed that protect bacterial spores from unfavorable conditions (spores of many bacteria can withstand heating up to 130 ° C, 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 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, they cause typhus, tick-borne rickettsiosis, and Rocky Mountain spotted fever. 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. organic matter: 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 nitrogenous, and then to nitric acid: 2NH 3 + 3O 2 = 2HNO 2 + 2H 2 O kJ 2HNO 2 + O 2 = 2HNO kJ Colorless sulfur bacteria oxidize hydrogen sulfide and accumulate sulfur in their cells: 2Н 2 S + О 2 = 2Н 2 О + 2S kJ With a lack of hydrogen sulfide bacteria further oxidation of sulfur to sulfuric acid: 2S + 3O 2 + 2H 2 O = 2H 2 SO kJ Iron bacteria oxidize bivalent iron to trivalent: 4FeCO 3 + O 2 + H 2 O = 4Fe (OH) 3 + 4CO kJ Hydrogen bacteria use energy released during the oxidation of molecular hydrogen: 2H 2 + O 2 = 2H 2 About kJ Physiology of bacteria


Reproduction of bacteria. The bacteria are capable of intensive reproduction. There is no sexual reproduction in bacteria; 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 cell cross-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, at one of the poles of the mother cell, a short outgrowth of the hypha is formed, 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 cell 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 participating 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. Purification Wastewater, the formation of methane Symbionts of many organisms (E. coli in humans) Cause infectious diseases (tuberculosis, tonsillitis) Currently, using transformed E. coli, insulin, growth hormone, interferon are obtained 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.

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 in comparison with the cytoplasm of eukaryotic cells is much poorer in structure composition. 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, the centriole is absent in the cell center, which is found only in algae. The reserve nutrient 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.




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"Study of the cell" - Table 2. Calculation of the magnification of the microscope. Onion skin cells under a microscope. Types of cells. Epigraph of the lesson. Conclusions. Preparation of a micropreparation. Lesson plan. The main parts of the cage. Table 1. Parts of the microscope. The story of the discovery of the cell. The main parts of the cell are: membrane, cytoplasm and nucleus. All living things have a cellular structure.

"Mitosis and Meiosis" - Vegetative reproduction. Breeding types. Cell cytokinesis (photo). Lumps of chromatin in the interphase nucleus. In anaphase 2, chromatids diverge to the poles, which become daughter chromosomes. The spindle filaments attach to the dichromatid chromosomes. Mitosis = division of the nucleus + division of the cytoplasm. Reproduction - reproduction of their own kind, ensuring the continuity and continuity of life.

"Meiosis lesson" - Meiosis. Chromosomal sex determination. The nitrogen cycle in the biosphere. Hereditary diseases... The carbon cycle in the biosphere. Plastic exchange. Metabolism. The phosphorus cycle in the biosphere. Comparison of mitosis and meiosis. Supporting notes used in the lessons.

"Energy exchange" - Reactions. (Glycolysis). Movie. Solve the problem. Learning new material Consolidation. Fermentation. 1 2. Enzymatic and anoxic process of decomposition of organic substances in the cell is observed in bacteria. Testing. Stages of energy metabolism. Substitute one word for the highlighted portion of each statement.

"Biology Meiosis" - Mitosis. Meiosis. Improving the visual perception of the material; Formation of search skills; Tasks: Cell division. Mitosis and meiosis. Purpose: Biology grade 9.

"The structure of the cell and its functions" - Exocytosis. Scheme of the structure of hereditary information. The number of mitochondria in one cell is from one to several thousand. The obligatory part of the cell, enclosed between the plasma membrane and the nucleus. Cell center. Chromoplasts. Organelle movement. Mitochondria is a universal organelle that is a respiratory and energy center.

Prokaryotes and eukaryotes
Vdovina E.

Prokaryotes and eukaryotes. Modern and
fossil organisms are known of two types
cells: prokaryotic and eukaryotic.
These cells vary so much in
structural features that were allocated two
super-kingdoms - prokaryotes (prenuclear) and
eukaryotes (real nuclear).
Intermediate forms between these
largest taxa alive so far
unknown.

Prokaryotes

PROCARIOTS
Prokaryotes. average value
prokaryotic cells 5 μm. They dont have
no internal membranes other than protrusions
plasma membrane. Instead of cellular
the nucleus has its equivalent (nucleoid),
devoid of a shell and consisting of one single DNA molecule. Besides
bacteria can contain DNA in the form
tiny plasmids similar to extra-nuclear DNA
eukaryotes. In prokaryotic cells capable of
to photosynthesis (blue-green algae, green
and purple bacteria) are available in various
structured large invaginations
membranes - thylakoids, according to their function
corresponding to eukaryotic plastids.
Similar invaginations (mesosomes) in
colorless cells perform functions
metochondria.

Eukaryotes

EUKARIOTS
Eukaryotes. Eukaryotic cells are more
size and more complex organization than
prokaryotic cells. They contain more DNA and
various components that provide it
complex functions. Eukaryotic DNA is contained in
the nucleus surrounded by a membrane, and in the cytoplasm
there are many others surrounded by membranes
organelle. These include mitochondria,
carrying out the final oxidation of molecules
food, as well as (in plant cells)
chloroplasts in which photosynthesis takes place. Whole line
data indicates the origin
mitochondria and chloroplasts from early
prokaryotic cells that have become internal
symbionts of a larger anaerobic
cells. Another distinctive feature
eukaryotic cells - this is the presence of a cytoskeleton
from protein fibers that organize the cytoplasm and
providing a movement mechanism.

 

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