“Oh, these bacteria!” Research work. Work: Bacteria Research work on the biology of bacteria
Maslov Arseniy
Research work of a 3rd grade student on the topic “Bacteria: harmful and beneficial.”
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Relevance... I once asked my parents a question, why do people get sick? Mom said that bacteria enter the body and the person gets sick. And then I started thinking, what are bacteria, where do they live, how do they reproduce and how are they dangerous? And are all bacteria harmful? Purpose of the study: to study the characteristics of the life of bacteria and find out whether they can be beneficial or harmful. Objectives: study the literature on the chosen topic; get acquainted with the variety and classification of bacteria; find out what harmful and beneficial bacteria there are; prepare homemade kefir
Object and subject of research Object of research: bacteria Subject of research: the importance of bacteria for humans Hypothesis Hypothesis: suppose that many bacteria live in the human body, they can be both beneficial and harmful, and they can be propagated at home. Research methods: Working with additional sources, searching for the necessary information; Observations and analysis of the information received; Experiments; Test; Data processing
History of the origin of bacteria Bacteria were first seen through an optical microscope and described in 1676 by the Dutch naturalist Antonie van Leeuwenhoek. The name “bacteria” was coined in 1828 by Christian Ehrenberg. Microbiology is the study of bacteria and their structure, which was formed in the second half of the 19th century as the science of pathogens, that is, as a branch of medicine. It is difficult to find a place on Earth where there are no bacteria. They are found in a wide variety of places: in the atmosphere and on the bottom of the oceans, in fast-flowing rivers and permafrost, in fresh milk and in nuclear reactors; however, there are especially many of them in the soil
The structure of bacteria A bacterium has a complex structure. The cell wall protects a single-celled organism from external influences, gives it a certain shape, provides nutrition and preservation of its internal contents. The plasma membrane contains enzymes and is involved in the process of reproduction and biosynthesis of components. Flagella are surface structures that serve to move cells in a liquid environment or on a solid surface. Cytoplasm serves to perform vital functions. In many species, the cytoplasm contains DNA, ribosomes, and various granules. Pili are thread-like structures, much thinner and have fewer flagella. They come in various types, differ in purpose and structure. Pili are needed to attach the organism to the affected cell.
Types of bacteria cocci (have a round shape); bacilli (have a rod-shaped form); spirilla (have a spiral shape); spirilla (have a spiral shape);
Classification of bacteria Beneficial bacteria E. coli It is an integral part of the intestinal flora of humans and most animals. Its benefits are difficult to overestimate: it breaks down indigestible monosaccharides, promoting digestion; prevents the development of pathogenic and pathogenic microorganisms in the intestines. Lactic acid bacteria Representatives of this order are present in milk, dairy and fermented products, and at the same time are part of the intestinal and oral microflora. They are capable of fermenting carbohydrates and in particular lactose and producing lactic acid, which is the main source of carbohydrates for humans. By maintaining a constantly acidic environment, the growth of unfavorable bacteria is inhibited. Bifidobacteria By producing lactic and acetic acids, they completely prevent the development of putrefactive and pathogenic microbes in the child's body. In addition, bifidobacteria: promote the digestion of carbohydrates; protect the intestinal barrier from the penetration of microbes and toxins into the internal environment of the body
Harmful bacteria Salmonella This bacterium is the causative agent of a very acute intestinal infection, typhoid fever. Salmonella produces toxins that are dangerous only to humans. Tetanus bacillus This bacterium is one of the most persistent and at the same time the most dangerous in the world. Produces an extremely toxic poison, tetanus exotoxin, leading to almost complete damage to the nervous system. Mycobacteria Mycobacteria are a family of bacteria, some of which are pathogenic. Various representatives of this family cause such dangerous diseases as tuberculosis, mycobacteriosis, leprosy (leprosy) - all of them are transmitted by airborne droplets.
My experiments... Making homemade kefir
Growing Bacillus subtilis One of the bacteria that is widespread in nature is Bacillus subtilis. It was first described in 1835. And it got its name due to the fact that the crop was originally isolated from rotten hay. This bacterium is one of the largest. It has a straight, elongated shape with blunt rounded ends and is usually colorless. This bacterium is quite easy to obtain at home. For work I needed the following: hay (you can buy it at a pet store), a saucepan with water, a jar with a wide neck, gauze for straining. For one liter of water you need to take 10 grams of hay. Boil the hay for 20 minutes. Strain the resulting broth and pour it into a jar, diluting 1:1 with settled cold water. I decided to pour the undiluted broth into another jar and see what came out of it. Place the jars in a warm place. The best conditions for the life of Bacillus hay are a large amount of dissolved organic substances, an abundance of oxygen and a temperature of about +30 degrees. Under such conditions, a film consisting entirely of bacteria should form on the surface of the hay decoction within two days.
Results of the “Bacteria” test It turned out that many guys do not know about the kingdom of bacteria and the existence of beneficial bacteria in our dairy products.
Conclusion While studying bacteria, I became acquainted with their diversity and classification, and was able to grow bacteria myself at home. I learned that there are a huge number of beneficial bacteria that we consume every day with fermented milk products and about harmful bacteria (dangerous to humans). I found out that bacteria are an irreplaceable part of our life and all living things. They are found absolutely everywhere and in everything and play a colossal role in human life. People have learned to use bacteria: Based on the above material and the research conducted, I believe that my hypothesis was confirmed: “Many bacteria live in the human body, they can be both useful and harmful, and they can be propagated at home.”
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Vasyankina Nina
Kulebaksky district, r.p. Gremyachevo, MBOU Gremyachevskaya secondary school, 7 b “Amazing bacteria.”
Head: Svetlana Andreevna Drews, biology teacher. MBOU Gremyachevskaya school No. 1
The purpose of the scientific work: to study the structural features and vital functions of bacteria, to determine their positive and negative effects on human life, to conduct laboratory work to detect bacteria.
Method of conducting: abstract research with practical work. Main results of the study: studied in detail the structure and activity of bacteria; determined the importance of bacteria in the biosphere and the national economy; carried out practical work on the detection of lactic acid bacteria, rotting bacteria, and studied their properties; I learned interesting facts about bacteria.
Introduction……………………………………………………………………………….4
Main part:
Discovery of the bacterial cell………………………………………………………......5
The structure and activity of bacteria……………………………………….....7
The importance of bacteria in the biosphere and the national economy…………………………..….10
Practical work “Detection of lactic acid bacteria, study of their properties”………………………………………………………………………………..13
Interesting facts about bacteria………………………………………………………16
Conclusion………………………………………………………………………………..17
Conclusion……………………………………………………………………………………….19
References…………………………………………………………………………………....20
Introduction
Selected topic of work “Amazing bacteria)” relevant, since much attention is currently paid to the study of microorganisms - bacteria and viruses, their effect on the human body. Scientists around the world are working to develop drugs against many infectious diseases.
While working on this topic, I set myself the following target: study of the structural features and vital functions of bacteria, determination of their positive and negative effects on human life.
To achieve this goal, I set myself the following tasks:
study in detail the structure and activity of bacteria;
determine the importance of bacteria in the biosphere and the national economy;
carry out practical work to detect lactic acid bacteria, rotting bacteria, and study their properties;
learn interesting facts about bacteria.
II. Main part
1. Discovery of a bacterial cell.
The branch of microbiology, bacteriology, studies bacteria. Bacteria were also among the first living organisms on Earth, appearing about 3.5 billion years ago.
Bacteria (ancient Greek - rod) is the kingdom of microorganisms, most often single-celled. Currently, about ten thousand species of bacteria have been described and it is estimated that there are over a million of them.
The bacteria were first seen through an optical microscope and described in 1676 by the Dutch naturalist Antonie van Leeuwenhoek. Like all microscopic creatures, he called them “animalcules.”
The name “bacteria” was coined by Christian Ehrenberg in 1828. Louis Pasteur in the 1850s initiated the study of the physiology and metabolism of bacteria, and also discovered their pathogenic properties.
Until the 19th century, microbiology was a collection of disparate facts. The founders of microbiology as a science were outstanding scientists of the 19th century, the French chemist L. Pasteur (1822-1895) and the Russian botanist L. S. Tsenkovsky (1822-1887). In 1862, Pasteur brilliantly proved that microorganisms do not arise spontaneously. He proved that infectious diseases are caused by various microbes. Pasteur prepared vaccines against rabies and anthrax. Tsenkovsky L.S. showed the closeness of bacteria with blue-green algae.
The development of methods for growing microbes on various solid nutrient media is associated with the name of the German doctor R. Koch (1843-1910), who discovered the anthrax bacillus, Vibrio cholerae and tuberculosis bacillus. After the work of L. Pasteur and R. Koch, microbiology was divided into a number of narrower specialties. There are general, agricultural, technical, veterinary and medical microbiology.
The works of S.N. Vinogradsky and V.L. Omelyansky played a major role in the development of general and soil microbiology. S. N. Vinogradsky established the fact of the assimilation of carbon dioxide by chlorophyll-free microorganisms, i.e., the ability to build their body entirely through the assimilation of inorganic substances. He proved the existence of anaerobic nitrogen-fixing bacteria; laid the foundation for the study of microorganisms inhabiting the soil. V.L. Omelyansky revealed the microbiological nature of the process of anaerobic decomposition of fiber. Among the researchers in the field of medical microbiology, D.K. Zabolotny should be noted, known for his work on the study of cholera and plague pathogens.
Soviet microbiologists have done a lot to develop measures to prevent infectious diseases. Much has been done in the field of studying issues of general microbiology and in the use of microorganisms in industry and agriculture. Microbes are widely used to produce alcohol, acetone, citric acid, yeast, and to produce antibiotics. In agriculture, bacterial fertilizers are used to increase crop yields.
Main part
2. The structure and activity of bacteria.
Bacteria - These are the smallest prokaryotic organisms with a cellular structure. Due to the microscopic size of cells from 0.1 to 10-30 microns, bacteria
According to the shape and characteristics of the association of cells, several morphological groups of bacteria are distinguished: spherical (cocci), straight rod-shaped (bacilli), curved (vibrios), spirally curved (spirilla), etc. Cocci linked in pairs are called diplococci, connected in the form of a chain - streptococci, in the form of clusters - staphylococci, etc. Filamentous forms are less common.
Cell structure. The cell wall gives the bacterial cell a certain shape, protects its contents from exposure to unfavorable environmental conditions, and performs a number of other functions. The basis of the cell wall of bacteria (like all prokaryotes) is a special substance - murein (a polysaccharide combined with several amino acids). Many types of bacteria are surrounded by a mucous capsule, which serves as additional protection for the cells.
The method of arrangement of flagella is one of the characteristic features in the classification of motile forms of bacteria.
The plasma membrane is no different in structure and function from the membrane of a eukaryotic cell. In some bacteria, the plasmalemma is capable of forming invaginations into the cytoplasm, called mesosomes. The folded membranes of mesosomes contain redox enzymes, and in photosynthetic bacteria, the corresponding pigments (including bacteriochlorophyll), due to which mesosomes are able to perform the functions of mitochondria, chloroplasts and other organelles, and also participate in nitrogen fixation.
The cytoplasm contains about 20 thousand ribosomes and one large circular double-stranded DNA molecule, the length of which is 700 or a thousand times the length of the cell itself. In addition, most types of bacteria also have small circular DNA molecules called plasmids in their cytoplasm. Bacteria lack membrane structures (organelles) characteristic of eukaryotic cells.
A number of aquatic and soil bacteria lacking flagella have gas vacuoles in the cytoplasm. By regulating the amount of gas in the vacuoles, aquatic bacteria can sink into the water column or rise to its surface, and soil bacteria can move in the soil capillaries. The reserve substances of the bacterial cell are polysaccharides (starch, glycogen), fats, polyphosphates, and sulfur.
Bacterial cell shapes.
Globular kinds - cocci. IN form spirals - spirilla. rod-shaped bacteria - bacilli.
Nutrition of bacteria.
Based on the type of nutrition, bacteria are divided into two groups: autotrophic and heterotrophic. Autotrophic bacteria synthesize organic substances from inorganic ones. Depending on what energy autotrophs use to synthesize organic substances, they distinguish between photo- (green and purple sulfur bacteria) and chemosynthetic bacteria (nitrifying bacteria, iron bacteria, colorless sulfur bacteria, etc.). Heterotrophic bacteria feed on ready-made organic substances of dead remains: (saprotrophs) or living plants, animals and humans (symbionts).
Saprotrophs include rotting and fermentation bacteria. The former break down nitrogen-containing compounds, the latter - carbon-containing compounds. In both cases, the energy necessary for their life is released.
Reproduction. Bacteria reproduce by simple binary cell division. This is preceded by self-duplication (replication) of the DNA molecule. Budding occurs as an exception.
When spores form in a bacterial cell, the amount of free water decreases, enzymatic activity decreases, the protoplast contracts and becomes covered with a very dense shell. Spores provide the ability to endure unfavorable conditions. They can withstand prolonged drying, heating above 100°C and cooling to almost absolute zero. In their normal state, bacteria are unstable when dried, exposed to direct sunlight, raised in temperature to 65-80°C, etc.; Under favorable conditions, the spores swell, forming a new bacterial cell.
Despite the constant death of bacteria (eating them by protozoa, exposure to high and low temperatures and other unfavorable factors), these primitive organisms have survived since ancient times due to their ability to reproduce quickly (cells can divide every 20-30 minutes), form spores, extremely resistant to environmental factors and their widespread distribution.
Cyanobacteria.
We will get acquainted with bacteria - “herbs”. A little moisture, air and sun are almost all they need to live. And these bacteria don’t look quite normal. So unusual that scientists for a long time considered them...algae! But studies have shown that these “algae” do not have a nucleus, and therefore, they must be classified as bacteria - prokaryotes. Because of their blue-green color, they were called cyanobacteria (cyanus in Greek for “blue”).
Cyanobacteria live in a wide variety of places. Imagine a barren rock. Day after day they “gnaw off” the smallest grains from the stone. The stone becomes covered with cracks into which plant roots can penetrate, and over time they crumble into grains of sand. And this started with cyanobacteria.
Has your aquarium “bloomed”? Are there dark green flakes or plaque on the walls? Warning sign! Cyanobacteria appeared in the aquarium. Some cyanobacteria release substances that are toxic to fish into the water. The processes of photosynthesis in cyanobacteria and eukaryotic organisms are carried out in a similar way. Their main storage carbohydrate is glycogen.
3. The importance of bacteria in the biosphere and the national economy.
The role of bacteria in the biosphere is great. Thanks to their vital activity, the decomposition and mineralization of organic substances of dead plants and animals occurs. The resulting simple inorganic compounds (ammonia, hydrogen sulfide, carbon dioxide, etc.) are involved in the general cycle of substances, without which life on Earth would be impossible. Bacteria, together with fungi and lichens, destroy rocks, thereby participating in the initial stages of soil-forming processes.
A special role in nature is played by bacteria that are capable of binding free molecular nitrogen, which is inaccessible to higher plants. This group includes free-living Azotobacter and nodule bacteria that settle on the roots of leguminous plants. Penetrating through the root hair into the root, they cause a strong proliferation of root cells in the form of nodules. At first, the bacteria live off the plant, and then they begin to fix nitrogen with the subsequent formation of ammonia, and from it nitrites and nitrates. The resulting nitrogenous substances are sufficient for both bacteria and plants. In addition, some nitrites and nitrates are released into the soil, increasing its fertility. The amount of nitrogen fixed by nodule bacteria can reach 450-550 kg/ha per year.
Bacteria play a positive role in human economic activity. Lactic acid bacteria are used in the preparation of a variety of dairy products (sour cream, curdled milk, butter, cheese, etc.). They also help preserve food. Bacteria are widely used in modern biotechnology for the industrial production of lactic, butyric, acetic and propionic acids, acetone, butyl alcohol, etc. During their life processes, biologically active substances are formed - antibiotics, vitamins, amino acids. Finally, bacteria are an object of research in the fields of genetics, biochemistry, biophysics, space biology, etc.
A negative role belongs to pathogenic, or pathogenic, bacteria. They are able to penetrate the tissues of plants, animals and humans and release substances that inhibit the body’s defenses. Pathogenic bacteria such as the causative agent of plague, tularemia, anthrax, pneumococci in the body of animals and humans are resistant to phagocytosis and antibodies. There are a number of other human diseases of bacterial origin that are transmitted by airborne droplets (bacterial pneumonia, tuberculosis, whooping cough), through food and water (typhoid fever, dysentery, brucellosis, cholera), through sexual contact (gonorrhea, syphilis, etc.) .
Bacteria can also infect plants, causing so-called bacteriosis (spotting, wilting, burns, wet rot, tumors, etc.). Bacteriosis is quite common in potatoes, tomatoes, cabbage, cucumbers, beets, legumes, and fruit trees.
Saprotrophic bacteria cause food spoilage. In this case, along with the release of carbon dioxide, ammonia and energy, the excess of which causes heating of the substrate (for example, manure, wet hay and grain) until it spontaneously ignites, the formation of toxic substances also occurs. Therefore, to prevent food spoilage, people create conditions under which bacteria largely lose their ability to reproduce rapidly and sometimes die.
Lactobacilli and bifidobacteria live in the human body. They appear in our body from the first years of infancy and remain in it forever, complementing each other and solving serious problems. Lactobacilli and bifidobacteria enter into complex reactions with other microorganisms and easily suppress putrefactive and pathogenic microbes. As a result, lactic acid and hydrogen peroxide are formed - these are natural internal antibiotics. Thus, lactobacilli raise, restore the body's defenses and strengthen the immune system.
The beneficial functions of lactobacilli were first noticed by the Russian scientist Ilya Ilyich Mechnikov. The idea of using fermented milk products to normalize biochemical processes in the intestines and nourish the body as a whole belongs to him.
Bacteria cause food spoilage. Therefore, to prevent food spoilage, people create conditions under which bacteria largely lose their ability to reproduce rapidly and sometimes die. Widespread methods of struggle with bacteria are: drying fruits, mushrooms, meat, fish, grain; their cooling and freezing in refrigerators and glaciers; marinating foods in acetic acid; pickling. When pickling cucumbers, tomatoes, mushrooms, or sauerkraut, the activity of lactic acid bacteria creates an acidic environment that inhibits the development of bacteria. This is what food preservation is based on. To destroy bacteria and preserve products, a method is used pasteurization— heating to 65°C for 10-20 minutes and sterilization method — boiling. High temperature causes the death of all bacterial cells. In addition, in medicine, the food industry, and agriculture, iodine, hydrogen peroxide, boric acid, potassium permanganate, alcohol, formalin and other inorganic and organic substances are used for disinfection, i.e., to destroy pathogenic bacteria.
Having studied various sources, I was convinced that all materials confirm The hypothesis of my project is that bacteria can be both harmful to humans and beneficial.
Practical work
Mini-study
Having received information that bacteria can be harmful and beneficial, I became interested in looking at them. To do this, I decided to conduct an experiment.
Description of the experiment.
In order to create a breeding ground for bacteria, I took a saucepan, put it on the stove and brought the water to a boil. Added a bouillon cube and a spoonful of sugar to the water. Boil this mixture for a few minutes. She took the saucepan off the heat and let it cool. I brought the broth to class. I poured the same amount of broth into each of the previously prepared vessels. Then she coughed into one of the vessels, stuck her finger into the other, and did not touch the third vessel.
Sticker "Don't drink!" on each vessel she warned everyone that an experiment was underway. She wrapped the vessels in plastic film and placed them in a warm place so that they would not disturb anyone.
After a while I checked what was happening with the broth. The liquid in the vessels became cloudy and began to emit an unpleasant odor, which confirms that there are bacteria in it.
After that, I took a few drops of liquid and tried to examine the bacteria using a magnifying device - a magnifying glass. But this did not lead to a positive result - I did not see any bacteria. Then I decided to resort to the help of another device - a light microscope.
At 200x magnification, I was able to see bacteria in all containers. I noticed that the most bacteria were in the vessel into which I put my finger. This once again confirms the fact that bacteria live on our hands. And the least amount of bacteria was in the third vessel. I would like to note that I was surprised by the small number of bacteria in all containers, although they were in a warm place for several weeks. I think this is due to the presence of preservatives (substances that allow food not to spoil for a long time) in the bouillon cube.
“Detection of lactic acid bacteria and study of their properties”
People first started talking about the benefits of fermented milk products at the beginning of the twentieth century, when Ilya Mechnikov (Russian biologist, Nobel Prize laureate) told the world about the beneficial properties of this product. In the course of his research, Mechnikov found out that our gastrointestinal tract, like fermented milk products, contains living microorganisms. They help the stomach function successfully.
Target: detect lactic acid bacteria and study their properties.
Equipment and materials: microscope, slides, cover slips, test tubes, kefir, curdled milk, rotten potatoes, alcohol, methyl blue.
Progress.
I am researching fermented milk products. To do this, you need to prepare smears of yogurt and kefir. I pour alcohol onto the air-dry smear and let it sit for 1-2 minutes.
I paint it with methylene blue. I examine preparations with an immersion lens. In a smear of curdled milk diplococci will be visible, in kefir - rods and yeast.
Experiment 1. Spoilage of milk by putrefactive microbes. I add a few drops of liquid from rotten potatoes to a test tube with milk and leave it in a warm place for 10-12 hours. As a result of the development of putrefactive bacteria, the milk protein will begin to dissolve and after 1-2 days it will completely dissolve with the release of foul-smelling gases.
Experiment 2. Preserving milk from spoilage by lactic acid bacteria. I add putrefactive and lactic acid bacteria into a test tube with milk. You can take 1-2 ml of kefir as a source of lactic acid bacteria. The development of lactic acid bacteria ensures the formation of lactic acid in milk, which suppresses the development of putrefactive bacteria. A normal milk clot is obtained in a test tube.
Conclusion: Fermented milk products contain three main types of beneficial bacteria: bifidobacteria, lactobacilli and enterobacteria. When we are healthy, our intestinal microflora includes probiotic lactic acid bacteria. It is thanks to their work that all other microorganisms living in our gastrointestinal tract manage not only to coexist peacefully with each other, but also to work effectively for our benefit.
Conducting a survey
After I got acquainted with the information about bacteria and conducted my own mini-research, I became interested in finding out how much the guys who study with me have this information.
For this purpose, together with the class teacher, we compiled a survey questionnaire. 24 students from our class were interviewed.
The survey included questions about bacteria and their importance in human life (see Appendix)
After analyzing the results, I learned that:
100% of students know about the existence of bacteria;
know that bacteria can cause various human diseases - 100% of students;
95.8% of students know that not all bacteria are harmful to humans;
100%, i.e. all students know that bacteria live in the human body, 75% believe that they help digest food and restore the body’s defenses;
Many guys know that people use bacteria in economic activities.
Interesting facts about bacteria.
Scientists have discovered a packaging structure for light-sensitive molecules in green bacteria that helps the organisms extremely efficiently convert sunlight into the chemical energy they need to live. The discovery could in the future lead to the creation of a new generation of solar cells, say the authors of the study published in the journal Proceedings of the National Academy of Sciences.
The green bacteria studied by scientists use light energy to process sulfur or iron compounds, similar to how plants use sunlight in photosynthesis. At the same time, organisms are forced to make do with a very limited amount of sunlight, since they live in the waters of hot hydrothermal springs or in seas at a depth of more than 100 meters.
Japanese experts have created the world's first micromotor, which is powered by bacteria. Its main rotating component has a diameter of 20 millionths of a meter.
Bacteria and bacillus are the same thing. The first word is of Greek origin, and the second is of Latin origin.
There are bacteria that help clean teeth. Scientists from the Swedish Karolinska Institute crossed these bacteria with ordinary yoghurt bacteria and are now trying to make transgenic yoghurt that will allow us not to brush our teeth.
The total weight of bacteria living in the human body is 2 kilograms.
There are about 40,000 bacteria in the human mouth. During a kiss, 278 different cultures of bacteria are transmitted from one person to another. Fortunately, 95 percent of them are harmless.
Conclusion
The role of prokaryotes in nature and human life is enormous. Bacteria, living in almost all environments, often determine various processes occurring in nature. The first inhabitants of the Earth were bacteria. The first bacteria appeared on earth more than 3 billion years ago.
Thanks to the influence of bacteria, the appearance and chemical composition of the Earth's shells changed, and thanks to this, the emergence of other life forms (for example, plants) became possible. Thanks to bacteria, the living shell of the Earth began to develop - the biosphere. Bacteria that reached land before plants participated in soil formation and created the conditions for plants to reach land. Currently, the role of bacteria is also very important.
1. Soil bacteria - rotting bacteria. They recycle dead organic matter. If it were not for these bacteria, the surface of the earth would be covered with a thick layer of the remains of dead organisms. It is these bacteria that ensure the circulation of substances in nature. They decompose dead remains into mineral salts, which are absorbed by plants.
2. Nitrogen-fixing bacteria. They settle on the roots of legumes (peas, alfalfa) and absorb nitrogen from the air, thereby enriching the soil with this element necessary for plant growth.
3. Lactic acid - used for the preparation of sour cream, kefir, fermented baked milk, cheese, sauerkraut, as well as for the production of silage.
4. E. coli - human companion. Lives in the intestines, helps break down milk sugar and produce vitamins.
5. Pathogenic bacteria - are causative agents of many diseases such as: tuberculosis, plague, dysentery, tetanus.
6. As you admire the blue flames on your gas stove, think about the tiny workers who brought natural gas to you. This methanobacteria , they process bottom residues, resulting in the formation of swamp gas - methane, which we use in everyday life.
7. Biotechnology, genetic engineering - a branch of modern biology, where bacteria are also indispensable. By inserting the necessary genes into the nuclear substance of bacteria, scientists force them to produce insulin, a drug used in the treatment of diabetes.
Conclusion
We render a verdict - the bacteria live, because... Without it, many processes will stop and the ecological balance will be disrupted.
Ah, this habitat! Everything is interconnected by exchange, food chains, composition, structure, fate...
In the thickets, and in the ridges, and in the villages, Where life breathes and moves, May there always be balance! Be careful not to disturb it!
Bibliography.
A.G. Elenevsky, M. A. Biology. Plants, fungi, bacteria. Bustard, 2001
Biology 6th grade. Lesson plans based on the textbook by I.N. Ponomareroy. Author-compiler G.V. Cherednikova. Volgograd. "Teacher" 2008 pp.144-146
Biology 10-11 grade. Lesson plans for the studies of V.I. Sivoglazov. Author - compiler T.V. Zarudnyaya. Volgograd. "Teacher" 2008 pp.70-71
General biology. 9th grade.V.B. Zakharov, A.G. Mustafin, Moscow. Enlightenment 2003.p. 44 - 46.
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ru.wikipedia.org›wiki/ Bacteria
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bigpi.biysk.ru›encicl/articles/00/1000056/…
slovari.yandex.ru›TSB› Bacteria
bril2002.narod.ru›b11.html
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Application
Diversity of bacteria
Introduction.
STRUCTURE AND LIFE ACTIVITY OF BACTERIA
Structure
Sensory functions and behavior
Reproduction and genetics
METABOLISM
Nutrition
Main sources of energy
Breath
BACTERIA AND INDUSTRY
Literature
Introduction
BACTERIA, a large group of unicellular microorganisms characterized by the absence of a cell nucleus surrounded by a membrane. At the same time, the genetic material of the bacterium (deoxyribonucleic acid, or DNA) occupies a very specific place in the cell - a zone called the nucleoid. Organisms with such a cell structure are called prokaryotes (“pre-nuclear”), in contrast to all others - eukaryotes (“truly nuclear”), whose DNA is located in a nucleus surrounded by a shell.
Bacteria, previously considered microscopic plants, are now classified into the independent kingdom Monera - one of five in the current classification system, along with plants, animals, fungi and protists.
Bacteria are much smaller than the cells of multicellular plants and animals. Their thickness is usually 0.5–2.0 µm, and their length is 1.0–8.0 µm. Some forms are barely visible at the resolution of standard light microscopes (approximately 0.3 microns), but species are also known with a length of more than 10 microns and a width that also goes beyond the specified limits, and a number of very thin bacteria can exceed 50 microns in length. On the surface corresponding to the point marked with a pencil, a quarter of a million medium-sized representatives of this kingdom will fit.
Partly due to the small size of bacteria, their metabolic rate is much higher than that of eukaryotes. Under the most favorable conditions, some bacteria can double their total mass and number approximately every 20 minutes. This is explained by the fact that a number of their most important enzyme systems function at a very high speed. Thus, a rabbit needs a few minutes to synthesize a protein molecule, while bacteria take seconds. However, in a natural environment, for example in soil, most bacteria are “on a starvation diet”, so if their cells divide, it is not every 20 minutes, but once every few days.
Given the variety of chemical reactions bacteria catalyze, it is not surprising that they have been widely used in manufacturing, in some cases since ancient times. Prokaryotes share the glory of such microscopic human assistants with fungi, primarily yeast, which provide most of the processes of alcoholic fermentation, for example, in the production of wine and beer. Now that it has become possible to introduce useful genes into bacteria, causing them to synthesize valuable substances such as insulin, the industrial application of these living laboratories has received a new powerful incentive.
Food industry. Currently, bacteria are used by this industry mainly for the production of cheeses, other fermented milk products and vinegar. The main chemical reactions here are the formation of acids. So, when preparing vinegar, bacteria of the genus Acetobacter oxidize ethyl alcohol contained in cider or other liquids to acetic acid. Similar processes occur when cabbage is sauerkraut: anaerobic bacteria ferment the sugars contained in the leaves of this plant into lactic acid, as well as acetic acid and various alcohols.
COMBATING BACTERIA IN INDUSTRY
Bacteria are not only beneficial; The fight against their mass reproduction, for example in food products or in the water systems of pulp and paper mills, has become a whole area of activity.
Food spoils due to the action of bacteria, fungi and its own autolytic (“self-digesting”) enzymes unless inactivated by heat or other means. Since bacteria are the main cause of spoilage, developing efficient food storage systems requires knowledge of the tolerance limits of these microorganisms.
One of the most common technologies is pasteurization of milk, which kills bacteria that cause, for example, tuberculosis and brucellosis. The milk is kept at 61–63°C for 30 minutes or at 72–73°C for only 15 seconds. This does not impair the taste of the product, but inactivates pathogenic bacteria. Wine, beer and fruit juices can also be pasteurized.
The benefits of storing food in the cold have long been known. Low temperatures do not kill bacteria, but they do prevent them from growing and reproducing. True, when frozen, for example, to –25° C, the number of bacteria decreases after a few months, but a large number of these microorganisms still survive. At temperatures just below zero, bacteria continue to multiply, but very slowly. Their viable cultures can be stored almost indefinitely after lyophilization (freeze-drying) in a protein-containing medium, such as blood serum.
Other known methods of storing food include drying (drying and smoking), adding large amounts of salt or sugar, which is physiologically equivalent to dehydration, and pickling, i.e. placing in a concentrated acid solution. When the acidity of the environment corresponds to pH 4 and below, the vital activity of bacteria is usually greatly inhibited or stopped.
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Purpose of the study: study the characteristics of the life activity of bacteria; Learn about diseases caused by bacteria and their prevention.
- study the available literature on this issue;
- analyze the effect of pathogenic bacteria on the human body;
- obtain and summarize information from an infectious disease specialist at Rospotrebnadzor about bacterial diseases in our area and their prevention.
Research methods:
- study of literature;
- collection of information;
- analysis of collected information and systematization;
- presentation of results.
Progress of the lesson
Introduction.
In 5th grade we started studying a new subject - biology. I was interested in the chapter “The Kingdom of Bacteria” and had questions:
Why are bacteria, relatively simple microscopic single-celled organisms, so viable?
What conditions contribute to the spread of pathogenic bacteria and what preventive measures exist?
Theoretical part
The bacteria were first seen under an optical microscope and described by the Dutch naturalist Antonie van Leeuwenhoek in 1676. Like all microscopic creatures, he called them “animalcules.”
The name “bacteria” was coined by Christian Ehrenberg in 1828.
Louis Pasteur in the 1850s initiated the study of the physiology and metabolism of bacteria, and also discovered their pathogenic properties.
Medical microbiology was further developed in the works of Robert Koch, who formulated the general principles for determining the causative agent of a disease (Koch's postulates). In 1905 he was awarded the Nobel Prize for his research on tuberculosis.
The study of the structure of a bacterial cell began with the invention of the electron microscope in the 30s of the 20th century.
The bacterial body consists of a single cell. This cell is structured completely differently than the cells of plants, animals and fungi. If their cells are separated by numerous partitions (membranes) into special compartments where the processes of respiration, nutrition, photosynthesis, etc. are carried out, then in bacteria the “partitioning” is in the most rudimentary stage. The most important difference is that the bacterium lacks a nucleus. Another difference is that there are no mitochondria or plastids. In bacteria, DNA is located in the center of the cell, coiled into a chromosome. If you “unwind” the bacterial DNA, its length will be about 1 mm.
Under favorable conditions, bacterial cells multiply very quickly, dividing in two. If a cell doubles every half hour, then it can give birth to offspring within a day. And some bacteria can multiply even faster.
And another interesting ability of bacteria. In unfavorable conditions they can often turn into spores. Such disputes remain alive for tens and hundreds of years, and in exceptional cases, even millions of years.
These characteristics of bacteria allow them to survive in any conditions.
Depending on the shape of the cells, bacteria are divided into several groups: spherical - cocci, rod-shaped - bacilli or rods, spiral - spirilla, in the form of a comma – vibrios.
Human diseases caused by bacteria
Bacterial diseases are one of the most common human diseases. Such diseases include some pneumonia (caused by streptococcus), anthrax (caused by Bacillus anthrax), cholera (caused by Vibrio cholerae), tuberculosis (caused by the tuberculosis bacillus (Koch bacillus), plague (caused by the plague bacillus) and others.
In ancient times and in the Middle Ages, this disease was called “Black Death,” which instilled panic in people. In the VI century. The plague epidemic killed 100 million people. Some states, such as the Byzantine Empire, were almost completely depopulated.
From 1346 to 1351, the plague (“the great pestilence”, as they said then) killed 24 million people - a quarter of the population of then Europe. The Italian Renaissance writer Giovanni Boccaccio begins his book “The Decameron” with a story about the plague epidemic in 1348: “At the beginning of the disease, some tumors appeared under the arms of men and women, growing to the size of an ordinary apple or egg; the people called them buboes. In a short time, this deadly tumor spread to other parts of the body, and then the sign of the said disease changed into black and purple spots that appeared on all parts of the body. It seemed that neither the doctor’s advice nor the power of the medicine helped or brought any benefit against this disease... neither the wisdom nor the foresight of man helped against it. Almost everyone died on the third day after the appearance of these symptoms.”
In the 20th century Plague epidemics practically ceased to threaten humans. Why did this happen? Of course, the systematic fight against this disease played a role. The black rat, whose fleas served as carriers of the disease, has almost disappeared, replaced by the gray rat. But still, a comprehensive and accurate answer to the question of why the plague epidemics stopped has not yet been found.
Cholera is often compared to the plague because of its transience and lethality. Cholera was brought to Europe only around 1816 from India, where it had been known since ancient times. In Russia, before 1917, more than 5 million people suffered from cholera, and half of them died.
By the end of the 20th century. Thanks to prevention, cholera epidemics have become quite rare. We are currently living in the era of the 7th pandemic. For Russia, the problem remains relevant; the epidemic situation is assessed as unstable.
Preventing cholera
Since cholera is a “disease of dirty hands,” it is necessary to systematically wash your hands before each meal, and in no case touch the mucous membranes of your mouth with unwashed hands. Wash your hands only with hot water. Products should be kept in places protected from flies and insects. Sanitation and hygiene skills are the main weapon in the fight against cholera.
TUBERCULOSIS.
The ominous symptoms of pulmonary tuberculosis (consumption) - weakness, shortness of breath, and in advanced cases, hemoptysis - were familiar to the inhabitants of Ancient Egypt and people who lived hundreds of thousands of years ago. This was shown by studies of their remains.
In ancient times and the Middle Ages, there was a belief that crowned persons could cure tuberculosis with their touch. English King Charles II in the 17th century. touched more than 90 thousand patients. A considerable fee was charged for the “treatment”, which went to the royal treasury.
Only in the 19th century. The first tuberculosis sanatoriums appeared. But the real fight against this disease began after Robert Koch discovered the tuberculosis bacterium in 1882.
Tuberculosis has not been completely defeated today. In the former Soviet Union, prisons and camps became breeding grounds for tuberculosis, where a significant proportion of prisoners became infected with the disease. Tuberculosis is a social infection. “The poorer the population, the more often they suffer from tuberculosis”
Prevention of tuberculosis
BCG vaccination is necessary for newborns. Next, at the stage of their maturation, a mandatory (every 8-12 months) Mantoux reaction is performed. It is advisable to choose a place of residence in dry, well-lit places. The apartment should be systematically wet cleaned and ventilated.
Paths of transmission of pathogenic bacteria
Airborne;
Handshake;
Houseware;
Contaminated water and food;
Disease carriers are rodents, fleas, ticks, lice, and cattle.
The poet Vladimir Mayakovsky, who took on all kinds of propaganda work, even wrote poetic explanations for a poster dedicated to the fight against cholera : “Citizen!
So as not to die from cholera,
take such measures in advance.
Don't drink raw water.
Drink only boiled water.
Also, don’t drink kvass on the street.
Boiling water is a lot of work.
So that you can keep up with your kvass early,
they just cook it from the tap...”
How does a bacterial infection progress?
With the development of a bacterial infectious process One of the first symptoms will be fever. Fever is a protective reaction of the body, since body temperature up to 39 degrees stimulates the immune system. If the body temperature rises above 39 degrees, then it must be brought down with paracetamol or, indirectly, with antibiotics (a decrease in body temperature within 24-48 hours from the start of antibiotic therapy is a sign of a properly selected antibacterial drug).
Another manifestation of a bacterial infectious process is intoxication syndrome. It manifests itself as a deterioration in health, apathy, decreased mood, headaches, pain in muscles and joints, nausea, vomiting, and the like are possible. To relieve these symptoms, you need to drink a lot of warm water (at least 2 liters per day). Excess water will dilute bacterial toxins, reducing their concentration, and also remove some of them in the urine.
These two signs of bacterial inflammation are universal to almost all infections. All other signs are determined by the characteristics of a particular pathogen, their exotoxins and other factors of aggression.
Immunity– the body’s immunity to a foreign agent, in particular to bacteria.
The human immune system protects our body constantly and always.
Task and human immunity find and neutralize bacteria that have entered the body, as well as their toxins.
To prevent illness from some bacterial diseases, vaccinations are carried out. In this case, weakened pathogens or poisons secreted by them are introduced into the body of a healthy person. The body creates special substances that help the subsequently vaccinated person quickly cope with pathogenic bacteria.
Practical part
It must be said that recently there has been a “replacement” of bacterial infections by viral ones, but their significance does not cease to be relevant. For example, in the 90s, having “calmed down” that diphtheria was not being registered, the percentage of people vaccinated against this infection decreased, resulting in an increase in morbidity and outbreaks of this infection with deaths that could have been avoided. Among bacterial infections, intestinal infections occupy a huge place:
- cholera
- typhoid fever
- dysentery
- salmonellosis.
Incidence of bacterial infections by country
| № | Diseases | Cases | Causes | Prevention |
| 1. | Cholera | 1994 – Chechen Republic, 415 cases; 2005 – Rostov region; 2006 – Murmansk region; 2008 – Bashkiria; 2010 – Moscow. |
Changes in socio-economic conditions: refugees, tourism, pilgrims; deterioration of the environmental situation – poor water quality | - Improving water quality Cleaning, sewerage of populated areas; Strict supervision over the work of public catering, the quality of products, removal of sick people from work; Compliance with personal hygiene rules; Veterinary control of animals |
| 2. | Typhoid fever | Cases of infection are constantly being recorded in Russia | Migration, unsatisfactory state of cleaning of populated areas; poor quality of water supply, public catering | |
| 3. | Dysentery Salmonellosis | Failure to comply with personal hygiene rules, consumption of contaminated products | ||
| 4. | Tuberculosis | The number of new cases has been constantly increasing in recent years | Social – poverty of the population | - Early immunization of newborns; Conducting the Mantoux reaction for all children; Fluorography (adult population) |
What about bacterial infections in our area? What are their causes and prevention? I learned about this from the infectious disease specialist of the territorial department of Rospotrebnadzor in the Valdai region, Natalya Tomovna Guseva.
Incidence of bacterial infections in the region
| Disease | 2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | ||||||||||
| area | region | |||||||||||||||||
| abs | per 100 thousand | abs | per 100 thousand | abs | per 100 thousand | abs | per 100 thousand | abs | per 100 thousand | abs | per 100 thousand | abs | per 100 thousand | abs | per 100 thousand | abs | ||
| Dysentery | 9 | 59,4 | 5 | 33,0 | 5 | 34,0 | - | - | - | - | - | - | - | - | - | - | ||
| Salmonellosis | - | - | - | - | 2 | 13,7 | - | - | - | - | - | - | 3 | 23,7 | 1 | 8,0 | ||
| Scarlet fever | 1 | 6,6 | - | - | 15 | 103,2 | 3 | 20,6 | 7 | 49,2 | 4 | 28,7 | - | - | 1 | 8,0 | ||
| Diphtheria | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | 7 | |
| Whooping cough | - | - | - | - | - | - | - | - | - | - | 3 | 21,5 | - | - | - | - | 7221 | |
| Meningococcal infection | 1 | 6,6 | - | - | - | - | - | - | - | - | 1 | 7,2 | - | - | 1 | 8,0 | ||
| Tuberculosis | 9 | 59,4 | 3 | 19,8 | 7 | 48,1 | 9 | 61,9 | 10 | 70,3 | 11 | 79,0 | 4 | 31,6 | 3 | 24 | ||
The diagram shows that over the past 5 years, no cases of dysentery and diphtheria have been recorded (although 7 cases were recorded in the region in 2012). Meningococcal infection (there was 1 death), salmonellosis and scarlet fever are constantly recorded. But the most noticeable increase is the number of new cases of tuberculosis patients and the average number of patients registered annually in our area is 6-7 people.
Recently, there have been many parents who refuse to vaccinate their children, thereby exposing their children to mortal danger, as well as endangering other children. It is reliably known that a reduction in morbidity is possible only with a high level of immunization of the population - 99%; in 2012, this figure for all infections in our area decreased to 94%.
The implementation of this research allowed me to develop skills in working with additional literature, the ability to conduct research, and substantiate the results of research.
During my research, I came to the following conclusion:
1) bacterial diseases are still one of the most common diseases;
2) to protect yourself from bacteria, you need to follow the rules of personal hygiene, do not eat unwashed fruits and vegetables, do not drink unboiled water, eat only fresh foods, and, of course, do not forget to wash your hands often.
3) an effective measure to prevent bacterial infections is immunization of children and adults.
Practical value The work is that the materials obtained can be used in biology lessons when studying the topic “Bacteria” or during extracurricular activities.
LITERATURE
1. Borisov L.B. and others. Medical microbiology, virology, immunology. M.: Medicine, 1994.
2. Vasiliev K.G. Segal A.E. History of epidemics in Russia. M.: Medgiz, 1960.
3. Likum A. Children's encyclopedia “Everything about everything.” M.: AST, 2008.
4. Galpershtein L.Ya. My first encyclopedia. ROSMEN, 2007.
5. Children's encyclopedia “I explore the world.” Medicine. M.: Astrel, 2006.
6. Internet resources (illustrated materials for the presentation)
Popova Veronica
Project Manager:
Elizarova Galina Ivanovna
Institution:
GKOU Volgograd sanatorium boarding school “Nadezhda”
In the presented biology research project "Bacteria" for grade 5, the author studies the types of bacteria, their effects on the human body, and also conducts a survey of classmates. The work contains background material about bacteria and a description of practical experiments conducted by the author.
In the process of working on research project in biology on the topic "Bacteria" 5th grade students were given the goal of researching bacteria living in the human body and the reproduction of bacteria at home.
The research work in biology on the topic “Bacteria” is based on an analysis of theoretical information about the origin and types of bacteria, and also a survey of students is conducted to determine their familiarity with the types of bacteria, their habitat and interaction with the human body.
In the proposed biology project "Bacteria" in grade 5, the author presented theoretical data on the peculiarities of the influence of bacteria on human health, and also conducted practical experiments in the reproduction of bacteria at home.
Some materials from this project on biology "Bacteria" can be used in grades 3 and 4, as well as in grades 6 and 7 at school as additional material for the lesson.
Introduction
1. Types of bacteria.
1.1 Lactobacilli.
1.2 Belly protector.
1.3 Head scratcher.
1.4 Bursting.
2. Questionnaire.
3. Experiments on the reproduction of bacteria at home.
Conclusion
Literature
Introduction
Bacteria - the smallest living creatures that can be found in every corner of the globe.
They were found in the streams of geysers with a temperature of about 105, in extremely salty lakes, for example in the famous Dead Sea. Living bacteria were discovered in the permafrost of the Arctic, where they remained for 2-3 million years.
In the ocean, at a depth of 11 km; at an altitude of 41 km in the atmosphere; in the depths of the earth's crust at a depth of several kilometers - bacteria were found everywhere. Bacteria thrive in water that cools nuclear reactors; remain viable after receiving a radiation dose 10 thousand times greater than lethal for humans.
Tasks:
- Find out what bacteria are.
- Conduct experiments on the growth of bacteria at home.
- Analyze information about bacteria.
Object of study - bacteria.
Subject of study - the importance of bacteria for humans.
Working methods:
- Experiments
- Observations
- Analysis of relevant literature
Relevance: the world of bacteria is part of our life.
Bacteria play a very important role in the living world. Bacteria were one of the first species to appear on Earth (they appeared approximately 4 trillion years ago), and it is more than likely that they will outlive us humans.
Despite their enormous diversity and the fact that they are found almost everywhere on Earth - on the ocean floor, and even in our intestines - bacteria still have something in common. All bacteria are approximately the same size (several micrometers).
