1. Introduction
2. Characteristics of bacteria
3. History of the discovery of microorganisms
4. Shapes of bacteria
5. Structure of bacteria
6. Spread of bacteria
7. Nutrition of bacteria
8. Reproduction of bacteria
9. Formation dispute
10. The role of bacteria in nature
11. The role of bacteria in human life
12. List the differences in the structure of a bacterial cell from a plant cell?
Introduction
- The science that studies bacteria is called bacteriology (microbiology). About 10,000 species of bacteria
- Bacteria are relatively simple microscopic single-celled organisms.
- divided by two departments: Crush and Cyanobacteria (Blue-green algae)
History of the discovery of bacteria
- The first person to see microorganisms was a Dutchman
Anthony van Leeuwenhoek:
“On April 24, 1676, I looked at the water... and with great surprise I saw in it a huge number of tiny living creatures...”
Anthony van Leeuwenhoek
Characteristics of bacteria
- The most ancient organisms on Earth, the first appeared about 3.5 billion years ago
- Unicellular organisms
- Microscopically small
- Bacteria do not have a nucleus ( prokaryotes – pre-nuclear)
- Have different handicaps
- Have different ways of feeding
- Distributed everywhere
Shapes of bacteria
Rod-shaped
Group name
Globular
Curved
tuberculosis
Spiral
vibrios
Spirilla
Spiral
Rod-shaped
Most bacteria are colorless.
Few are colored purple or green
spherical shape
Structure of bacteria
- Available dense cellular membrane covered on top with mucous membrane capsule
- Typical no kernel - there is nuclear matter, non-nuclear
- Majority has flagella
- Can have inclusion with a supply of nutrients
Spread of bacteria
- Distributed everywhere:
In the air
In living organisms
- In 1 cubic see water near cities contains up to 400,000 bacteria
- There are especially many bacteria in fertile soil, 1 cubic meter. cm soil more than a million bacteria
Nutrition of bacteria
- Most bacteria feed on ready-made organic substances - heterotrophs:
- saprophytes
- symbionts
- Some bacteria are capable of creating organic substances themselves from inorganic ones - autotrophs:
- photoautotrophs ( cyanobacteria)
- chemoautotrophs
Metabolism:
- They live in an oxygen environment aerobes
- They live in an oxygen-free environment anaerobes
Bacteria reproduction
- They reproduce by dividing one cell into two (fragmentation)
- Under favorable conditions, the division process occurs every 20 - 30 minutes
- Restrains the growth of bacteria:
sunlight
Lack of food
Heat
Disinfectants
Interspecies fight
Stages of bacterial crushing
Education dispute
- When unfavorable conditions occur, the bacterium turns into a spore
- The dispute persists for a very long time
- In spore form, bacteria can be spread by wind, water
- Once in favorable conditions, the spores germinate and become a living bacterium.
Bacterial spore formation
The role of bacteria in nature
- An important link in cycle of substances in nature
- Decompose complex substances to simple ones that use plants again
- Bacteria rotting decomposes the corpses of animals and dead plants , form humus - planetary orderlies
- Soil bacteria turn humus into minerals
- Nitrogen-fixing bacteria absorb nitrogen air, form nitrogen compounds in the soil (symbiosis with legumes
The role of bacteria in human life
- Infection occurs :
- when communicating with a patient,
- when consuming food or water with pathogenic bacteria
- unsanitary living conditions
- failure to comply with personal hygiene rules
- Mass disease of people - epidemic
- Patients receive medicine , and in the premises they conduct disinfection
- Used in Food Industry lactic acid bacteria
- They spoil food
- They spoil fishing nets, rare books, hay, etc.
- Cause disease person:
- typhus, cholera, diphtheria, tetanus, tuberculosis, sore throat, meningitis, glanders, anthrax, brucellosis and other diseases
List the differences in the structure of a bacterial cell from a plant cell?
- Lack of core
- Absence of vacuole, chloroplasts
- The presence of flagella, which they need for movement
- Dense, cellulose-free casing
- Pasechnik V.V. Biology. Textbook. 6th grade
- Korchagina V.A. Biology. Textbook. 6th grade
- Serebryakova T.I. Biology. Textbook. 6th grade
General characteristics of bacteria Bacteria are the most ancient group of organisms. The first bacteria appeared more than 3.5 billion years ago. And they were the only living creatures on our planet. These are the first representatives of living nature; their body had a primitive structure. Bacteria are considered representatives of PROKARYOTES, because. do not have a core.
The structure of a bacterium The cell wall performs a protective and supporting function Cytoplasm fills the space inside the cell Flagella or villi are organs of movement The outer shell or capsule protects DNA from drying out or the nuclear substance carries hereditary information The plasma membrane is permeable, metabolism occurs through it Conclusion: the bacterium does not have a separate nucleus
Living conditions for bacteria Aerobic 1. Live in the air 2. Capable of breathing oxygen - the most effective way to obtain energy Anaerobic 1. Live in an oxygen-free environment 2. Energy is obtained as a result of fermentation - an ancient energetically unprofitable process Acetic bacteria Staphylococcus Clostridium - soil bacterium
Reproduction of bacteria 1. Bacteria reproduce very easily. The mother cell divides in half. The result is two young bacterial cells. 2This happens extremely quickly. A bacterial cell can divide within minutes. 3. If all the resulting bacteria “survived,” they would cover our planet with a thick layer... But most of them die before they can reproduce!
Spore formation 1. With a lack of nutrients or accumulation of metabolic products - spore formation. 2. Spores can remain dormant for a long time. 3. Spores can withstand prolonged boiling and freezing. 4. When favorable conditions occur, the spore germinates and becomes viable. CONCLUSION: Bacterial spores are an adaptation to survival in unfavorable conditions.
Conclusions 1. Bacteria are the oldest group of living beings on the planet 2. The bacterial cell has a simple structure 3. It does not have a nucleus and the cytoplasm is immobile 4. Bacteria are classified as prenuclear organisms or prokaryotes 5. In unfavorable conditions they form spores
Project work passport.
Project name " Bacteria in our life"
The project manager is I.A. Shtreker, teacher of biology and chemistry of Municipal Budgetary Educational Institution Secondary School No. 24 of the village. Kaz.
The academic subject is biology, within which the work is carried out.
Academic disciplines close to the topic of the project: history, computer science.
Age 13
Project type: Research
Target
To experimentally confirm the importance of our living conditions for the growth and development of bacteria.
Tasks
1.Study the effect of bacteria on dairy products;
2.Study methods of combating pathogenic bacteria;
3.Study hygiene rules.
I, Maria Zhuravleva, decided to investigate the effect of bacteria on milk and potatoes and make a presentation on the topic “Bacteria in our lives.” I decided to make this presentation and defend it at a school environmental conference.
My work plan:
Selecting a topic.
Search for information
Study
Making a Presentation
5. Project protection.
What are microbes?! Where did they come from and what do they look like?! We hear on TV and radio, read in newspapers and on the Internet that bacteria and microbes are harmful organisms and they live in the environment around us - air, soil, water - from where they then end up on objects, clothes, hands, and food. , in the mouth, intestines.
The sizes of microbes are so small that they are measured in thousandths and even millionths of a millimeter. Microbes can only be seen using an optical or electron microscope. They can cause various diseases and poisoning. Therefore, it is necessary to comply with sanitary and hygienic requirements.
There are a huge number of microbes, but which ones live in us?! How do they differ and do they exist at all?!
In total, scientists counted 500 species of bacteria in the samples.
Hypothesis: I want to make sure that there are bacteria on our hands. And is it really necessary to wash your hands to protect yourself from bacteria?
Relevance: Do bacteria exist on our hands?
Problem: ways to protect against bacteria.
History of discoveries
It became possible to see a microbe after the invention of the microscope. The first to see and describe microorganisms was the Dutch naturalist Antony van Leeuwenhoek (1632-1723), who constructed a microscope that provided magnification up to 300 times. Through a microscope, he examined everything that came to hand: pond water, various infusions, blood, dental plaque and much more. In the objects he examined, he discovered the smallest creatures, which he called “living animals.” He established spherical, rod-shaped and convoluted forms of microbes. Leeuwenhoek's discovery marked the beginning of the emergence of microbiology.
French chemist Louis Pasteur (1822-1895) was the first to study bacteria and their properties. He proved that microbes cause fermentation and decay and can cause disease.
I. I. Mechnikov (1845-1916) deserves great credit for the development of microbiology. It also identified human diseases caused by bacteria. He organized the first bacteriological station in Russia. The name of Mechnikov is associated with the development of a new direction in microbiology - immunology - the study of the body's immunity to infectious diseases (immunity).
Habitat
Bacteria are the very first living creatures to appear on our planet.
Bacteria live almost everywhere there is water, including hot springs, the bottom of the world's oceans, and deep inside the earth's crust. They are an important link in metabolism in ecosystems.
There is practically no place on Earth where bacteria are found. They live in the ice of Antarctica at a temperature of -83 Celsius and in hot springs (volcano or desert), where the temperature reaches +85 or +90 Celsius. There are especially many of them in the soil. 1 gram of soil can contain hundreds of millions of bacteria.
The number of bacteria is different in the air of ventilated and unventilated rooms. So, in the classroom after ventilation before the start of the lesson there are 13 times less bacteria than before ventilation
1.3. What types of bacteria are there? Bacteria can be both beneficial and harmful.
For many animals, bacteria are simply necessary for life. For example, plants are known to serve as food for ungulates and rodents. The bulk of any plant is fiber (cellulose). But it turns out that bacteria living in special parts of the stomach and intestines help animals digest fiber.
We know that putrefactive bacteria spoil food. But the harm they bring to humans is nothing compared to the benefits they bring to nature as a whole. These bacteria can be called “natural orderlies.” By decomposing proteins and amino acids, they support the cycle of substances in nature.
Curdled milk, cheese, sour cream, butter, kefir, sauerkraut, pickled vegetables - all these products would not exist if it were not for lactic acid bacteria. Man has been using them since ancient times. By the way, yogurt is absorbed three times faster than milk - in an hour the body completely digests 90% of this product. Without lactic acid bacteria there would be no silage for livestock feed.
Structure of bacteria
The structure depends on the way of life and food supply of the microorganism. Bacteria can have rod-shaped (bacilli), spherical (cocci) and spiral-shaped (spirilla, vibrio, spirochetes) shapes.
How they infect us? Contagious (infectious) diseases have been known since ancient times. The most severe of them (plague, cholera, smallpox) often spread massively and caused widespread pestilence, as a result of which flourishing cities turned into vast cemeteries.
In addition to these particularly dangerous infections, there are many other known infectious diseases that can cause epidemics - dysentery, typhoid and paratyphoid fever, typhus and relapsing fever, brucellosis, these diseases occur through dirty food and hands. The method of infection is the transfer of the pathogen into the respiratory tract through the air around us. The causative agents of many infectious diseases are secreted by the sick body from the affected respiratory tract (nose, pharynx, bronchi, lungs). When a sick person speaks, coughs, or sneezes, he throws tiny sprays into the surrounding air - droplets of infected sputum or nasal mucus. In this way, pathogenic microbes easily penetrate along with contaminated air into the nose, pharynx, and lungs of healthy people, where the further development of the disease occurs. This “air” or “droplet” path of movement of infectious microbes is observed when healthy people are infected with influenza, scarlet fever, measles, diphtheria, whooping cough, smallpox, and mumps.
Survey-observation.
I interviewed 20 people about how they wash their hands before eating, 19 people know that they need to wash their hands with soap before eating - this is 98% of students. After the work done, I was interested in the question: “How often do students wash their hands before eating?” During the break, I began to observe at the entrance to the dining room, did the students wash their hands?
Result:
When surveying students, “Do they know that it is necessary to wash their hands before eating?”, 98% of students answered that they know and understand why this is necessary.
Having observed the schoolchildren at the entrance to the dining room, I found out that about 8 people washed their hands without soap before eating, and 12 people did not wash their hands.
Conclusion: it is not enough to know, you also need to apply knowledge to maintain your health.
My experiences.
I washed, peeled the potato tuber, cut it into 2 parts, soaked it in a soda solution, boiled it, cooled it. I made 2 glass jars with lids sterile, put a share of potatoes in the No. 1 jar with dirty hands, and a share of potatoes in the No. 2 jar with hands washed with soap. Placed the jars in a warm place. As a result, after 4 days, the potatoes that were taken with dirty hands were densely covered with colonies of bacteria, and in jar No. 2 the potatoes were partially covered with colonies.
Conclusion: dirty hands have a lot of bacteria.
Experiment No. 2 (with milk)
Making curdled milk from milk.
I took 1 glass of fresh milk, put it in a warm place, the next day I got yogurt
Making sour cream from cream.
I took 1 cup of cream and put it in a warm place, a day later it turned out to be sour cream
Conclusion: Thus, I was convinced that beneficial bacteria help make many delicious foods.
Lesson topic: Bacteria are the oldest group of living organisms.
General characteristics of bacteria.
Differences between bacterial cells and plant cells.
Lesson objectives:
educational: form the concept of bacteria as the oldest
group of living organisms;
developing: develop cognitive and creative activities
students; group work skills, logical
thinking;
educational: cultivate a culture of behavior in group and
individual work.
Lesson type: lesson explaining new material
Teaching methods: visual, partially exploratory, practical
Equipment: slide presentation, video clips “Rotting of fruits and vegetables”, “Invisible life”, virtual laboratory “Preparation of a microslide and examination of the bacterium Bacillus subtilis”
Didactic material: task cards, sheets with additional information
During the classes:
I. Organizing time
Set up for the lesson.
Greetings
Training "Hello!"
Students take turns touching the fingers of the same name on their neighbor’s hands, starting with the thumbs, and say:
I wish (thumbs touching);
success (index);
large (medium);
in everything (nameless);
and everywhere (little fingers);
Hello! (touch with whole palm)
Division into groups
Appointment of speakers, distribution of evaluation sheets.
IV. Preparation for active and conscious assimilation of new material
Strategy "Tree of Expectations" Students write down the expected results from the upcoming lesson on stickers and stick them to the tree.
Screening of the video clip “Rotting of Fruits and Vegetables”
Show a slide with different types of bacteria.
Question:
These small organisms created life on Earth, carry out the global cycle of substances in nature, and also serve humans.
Louis Pasteur called them “the great gravediggers of nature.” Who are they?
Name these small organisms.
Statement of the topic and objectives of the lesson.
V. Stage of learning new material
Screening of the video clip “Invisible Life”
If there were such a book of records of living organisms, then podium bacteria would come first.
Today you have to familiarize yourself with the topic. And determine for what achievements medals can be awarded to bacteria.
To make your work easier, I would like to present the first medal myself. Thismedal for antiquity .
You already know from the evolution section that the first living organisms appeared in water billions of years ago. And these were primitive organisms - bacteria. It was bacteria with chlorophyll that first saturated the Earth's atmosphere with oxygen and only then did the first plants appear. That's why we awarded the medal for antiquity.
Exercise: study §55 p.183 and additional information on the tables.
To get acquainted with the topic, 5-7 minutes are provided. Time managers control time. After studying the topic, each team will have to present a medal to the bacteria and explain for what merit this medal was awarded.
Physical education minute
VI. Checking your understanding of new material
Students fill out an answer sheet with tasks (+, -)
| Do you believe that... | ||||
| Bacteria nuclear organisms | ||||
| Aerobic and anaerobic respiration | ||||
| The discoverer of the bacterium, Anthony van Leeuwenhoek | ||||
| Right answers: | Peer assessment: |
|||
Evaluation criterion:
9-10 points “5”
7-8 points “4”
5-6 points "3"
VII. Topic consolidation stage
Laboratory work No. 30“Examination of the appearance of Bacillus subtilis”
Goal: to verify the structural features of the Bacillus subtilis bacterium.
Virtual laboratory “Preparation of a microslide and examination of the bacterium Bacillus subtilis”
http://biolicey2vrn.ru/index/bakterija_sennaja_palochka/0-474
Conclusions for the lesson
1. Bacteria are primitive single-celled organisms that are microscopic in size.
2. Bacteria are ubiquitous.
3. They reproduce very quickly under favorable conditions.
4. A spore is a bacterial cell with a dense shell.
5. They feed in an autotrophic and heterotrophic way.
6. They breathe aerobically and anaerobically.
VIII. Lesson summary
Reflection
Strategy "Tree of Expectations" Students whose expectations were met at the end of the lesson remove their stickers from the “expectation tree” and read them out.
Grading a lesson
Homework information
Study §55.
Prepare messages on the topics: “Painful bacteria”, “Nodule bacteria”, “Lactic acid bacteria”.
Assessment sheet
| Student's full name | "Mnemonics" | Self-assessment | Teacher rating | final grade |
||
Assessment sheet
Class________ Team______________
| Student's full name | Evaluation when compiling a medal | "Mnemonics" | Blitz poll “Do you believe that...” | Self-assessment | Teacher rating | final grade |
Bacteria.
There is practically no place on earth where bacteria are not found. These are the most ancient creatures on earth, which appeared about three and a half billion years ago. For comparison: the earth arose four billion years ago, and the universe fourteen, humanity several tens of thousands of years ago. There are especially many bacteria in the soil; one gram of soil can contain hundreds of millions of bacteria.
Bacteria are the smallest creatures on the ground. Scientists know about 10,000 species of bacteria. They can only be examined under a microscope, because... their sizes are very small and they are colorless. The cells of living organisms are approximately the same size, and the cells of bacteria are ten times smaller than the cells of other organisms. Even the largest ones do not exceed 0.01 microns, but most are much smaller.
When studying bacteria under a microscope, scientists noticed that bacteria are not just similar to each other, they have the ability to have several external appearances, that is forms bacteria.
Shape of bacteria.
spherical (cocci)
rod-shaped (bacillus)
convoluted (vibrios)
similar to a spiral (spirilla)
spirochetes (6-10 turns)
streptococci (chain of cocci)
staphylococci (clusters of cocci)
The simplest form of bacteria is a ball, it is called coccus, which translated means “berry”. When multiplying, cocci sometimes remain connected in pairs, such a connection is called diplococcus, with a larger amount a chain is formed, which is called streptococcus. When cocci are connected in clusters, they get the name staphylococcus. Cocci that have an elongated shape are called sticks, if they have a curved shape, then they are called vibrio. Spiral-shaped long bacteria are called - spirilla or spirochete. There are other forms, but these are the most important.
The shape determines the abilities of bacteria such as attachment to the surface, mobility, and absorption of nutrients. In addition, bacteria can live in colonies.
Bacteria
History of the study of bacteria.
The Dutch naturalist Antonie van Leeuwenhoek first saw bacteria in an optical microscope in 1676 and called them “animalcules.”
Christian Ehrenberg coined the name “bacteria” in 1828.
Louis Pasteur in the 1850s initiated the study of the physiology and metabolism of bacteria, and also discovered their pathogenic properties.
Robert Koch formulated the general principles for identifying the causative agent of a disease. In 1905 he was awarded the Nobel Prize for his research into tuberculosis.
M.V. Beyerinck and S.N.Vinogradsky laid the foundations of general microbiology and the study of the role of bacteria in nature.
Bacteria very prolific . Reproduce bacteria dividing one cell into two. Under favorable conditions, cell division in many bacteria can occur every 20-30 minutes. With such rapid reproduction, the offspring of one bacterium in 5 days is capable of forming a mass that could fill all the seas and oceans. However, this does not happen in nature, since most bacteria quickly die under the influence of sunlight, drying, lack of food, etc.
In order to tolerate unfavorable conditions, bacteria have learned to form disputes – special forms of bacteria. They are formed when the bacteria inside its shell dries out, decreasing in size. In this case, the contents of the cell, shrinking, move away from the shell, become rounded and form on its surface, being inside the mother shell, a new, denser shell. Spores (from the Greek word "spore" - seed) of some bacteria persist for a very long time in the most unfavorable conditions. They can withstand drying, heat and frost, and do not immediately die even in boiling water. Spores are easily spread by wind, water, etc. There are many of them in the air and soil. Under favorable conditions, the spore germinates and becomes a living bacterium. Bacterial spores are an adaptation to survive in unfavorable conditions.
Bacteria
The living conditions of bacteria are very diverse.
Type breathing among bacteria there are aerobes and anaerobes .
Like all living things, most bacteria require oxygen. However, there are bacteria that can live without oxygen. Once in an environment where there is a lot of oxygen, they die. Under natural conditions, bacteria that require oxygen live on the surface of the soil, in the upper layers of water, and in the atmospheric air. Those bacteria for which oxygen is destructive live in the deep layers of the soil, in silt, and in the water column.
Bacteria
The life activity of bacteria can occur in different temperature conditions. Some of them are able to develop under temperature conditions from -2 to +75 degrees. Bacteria can live in places where virtually nothing can survive: boiling geysers, underground oil lakes, acid lakes where there are no fish. Some bacteria can survive even in space. But the most favorable temperature for most bacteria can be considered from +4 to +40 degrees. At higher temperatures, many types of bacteria die. To destroy bacteria, they are exposed to steam at a temperature of 120 degrees for 20 minutes. Sun rays are also harmful to bacteria.
The structure of a bacterium. Each bacterium is just one cell with a thin membrane and cytoplasm.
A bacterium, like any cell, is covered cell membrane, on top of the cell membrane there is a special protective shell - cell wall, which is made from a special substance - murein. The liquid part of the cell is called cytoplasm. Bacteria prokaryotes , they do not have a nucleus, instead there is a clot of cytoplasm in which there is a molecule that carries information - a DNA molecule, and is called nucleoid, translated as "core-like". Flagellum bacteria are necessary for movement, but not all bacteria have a flagellum, and not all of them are capable of movement. Not all bacteria have special villi(bacilli are covered with hairs - pili), of which there are two types: some of which attach the bacterium to the necessary surfaces, others serve to transmit information between bacteria. Inside the bacterium is storage nutrient. Both the cell wall and the cell membrane are permeable to substances that bacteria need for life, primarily for nutrition. When harmful substances for bacteria are formed, they are also removed through the shell and membrane, which is how bacteria metabolize.
Blitz poll “Do you believe that” (+, -).
| Do you believe that... | ||||
| Bacteria are ubiquitous | ||||
| Divided into three groups based on shape | ||||
| Spherical bacteria - cocci | ||||
| Bacteria nuclear organisms | ||||
| Autotrophic and heterotrophic mode of nutrition | ||||
| Form spores during reproduction | ||||
| The hereditary substance is located in the nucleus | ||||
| Aerobic and anaerobic respiration | ||||
| The science that studies bacteria - microbiology | ||||
| Right answers: | Peer assessment: |
|||
Blitz poll “Do you believe that” (+, -).
| Do you believe that... | ||||
| Bacteria are ubiquitous | ||||
| Divided into three groups based on shape | ||||
| Spherical bacteria - cocci | ||||
| Bacteria nuclear organisms | ||||
| Autotrophic and heterotrophic mode of nutrition | ||||
| Form spores during reproduction | ||||
| The hereditary substance is located in the nucleus | ||||
| Aerobic and anaerobic respiration | ||||
| The science that studies bacteria - microbiology | ||||
| Discoverer of the bacterium, Anthony van Leevehoek | ||||
| Right answers: | Peer assessment: |
|||
Blitz poll “Do you believe that” (+, -).
| Do you believe that... | ||||
| Bacteria are ubiquitous | ||||
| Divided into three groups based on shape | ||||
| Spherical bacteria - cocci | ||||
| Bacteria nuclear organisms | ||||
| Autotrophic and heterotrophic mode of nutrition | ||||
| Form spores during reproduction | ||||
| The hereditary substance is located in the nucleus | ||||
| Aerobic and anaerobic respiration | ||||
| The science that studies bacteria - microbiology | ||||
| Discoverer of the bacterium, Anthony van Leevehoek | ||||
| Right answers: | Peer assessment: |
|||
Blitz poll “Do you believe that”
Students fill out an answer sheet with tasks (+, -).
| Do you believe that... | ||||
| Bacteria are ubiquitous | ||||
| Divided into three groups based on shape | ||||
| Spherical bacteria - cocci | ||||
| Bacteria nuclear organisms | ||||
| Autotrophic and heterotrophic mode of nutrition | ||||
| Form spores during reproduction | ||||
| The hereditary substance is located in the nucleus | ||||
| Aerobic and anaerobic respiration | ||||
| The science that studies bacteria - microbiology | ||||
| Discoverer of the bacterium, Anthony van Leevehoek | ||||
| Right answers: | Peer assessment: |
|||
Reception "Mnemotechnics" Expressions on the topic are read out, students do not write anything down. After this, students reproduce them from memory in their notebooks. At the end, the winner is revealed, the one who remembers the most words.
Strateria "Traffic Light" formative assessment.
Green card - satisfied with myself, I did everything in my power and even more
Yellow card – could have done better
Red card – I’m not happy, I didn’t do everything I could.
