bacteria. Bacteria - the most ancient organisms on Earth Bacteria - the oldest group of living organisms

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 most ancient

a group of living organisms;

developing: develop cognitive and creative activity

students; group work skills, logical

thinking;

educational: to 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 fruits and vegetables", "Invisible life", virtual laboratory "Preparing a micropreparation and examining the bacterium hay bacillus"

Didactic material: task cards, sheets with additional information

During the classes:

I. Organizing time

Set up for the lesson.

Greetings

training "Hello!"

Students alternately touch the fingers of the same name of their neighbor, starting with the thumbs and say:

I wish (thumbs touch);

success (indicative);

large (medium);

in everything (nameless);

and everywhere (little fingers);

Hello! (touch with whole hand)

Division into groups

Appointment of speakers, distribution of evaluation sheets.

IV. Preparation for active and conscious assimilation of new material

Expectation tree strategy Students write down the expected results from the upcoming lesson on sticky notes and stick them to the tree.

Showing the video fragment "Rotting fruits and vegetables"

Slide show with different types of bacteria.

Question:

These small organisms created life on Earth, carry out the global circulation of substances in nature, and also serve humans.

Louis Pasteur called them "the great gravediggers of nature." Who are they?

Name these small organisms.

Message topics, objectives of the lesson.

V. Stage of assimilation of new material

Screening of the video fragment "Invisible Life"

If there were such a book of records of living organisms, then podium bacteria would come first.

Today you have to independently familiarize yourself with the topic. And determine for what achievements you can award medals to bacteria.

In order to make it easier for you to work, 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 the bacteria that had chlorophyll that first saturated the Earth's atmosphere with oxygen and only then, the first plants appeared. That's why we gave 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 bacterium, and explain for what merits this medal was awarded.

Physical education minute

VI. Checking understanding of new material

Students complete the answer sheet with tasks (+, -)

	Do you believe that...



	Bacteria nuclear organisms



	Respiration aerobic and anaerobic

	Bacteria discoverer Anthony van Leeuwenhoek
Right answers:		Mutual evaluation:

Evaluation criterion:

9-10 points "5"

7-8 points "4"

5-6 points "3"

VII. Topic pinning stage

Lab #30"Review of the Appearance of the Hay Bacillus Bacillus"

Purpose: to verify the structural features of the bacterium hay bacillus.

Virtual laboratory "Preparation of a micropreparation and examination of the bacteria hay bacillus"

http://biolicey2vrn.ru/index/bakterija_sennaja_palochka/0-474

Conclusions to the lesson

1. Bacteria are primitive unicellular organisms with microscopic dimensions.

2. Bacteria are ubiquitous.

3. They reproduce very quickly under favorable conditions.

4. Spore - a bacterial cell with a dense shell.

5. They feed in an autotrophic and heterotrophic way.

6. Breathe aerobically and anaerobically.

VIII. Lesson summary

Reflection

Expectation tree strategy Students who met their expectations 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: “Pathogenic bacteria”, “Nodule bacteria”, “Lactic acid bacteria”.

Assessment sheet

Full name of the student	"Mnemonics"	self-assessment	Teacher evaluation	final grade

Assessment sheet

Class _______ Team ______________

Full name of the student	Evaluation when compiling a medal	"Mnemonics"	Blitz poll "Do you believe that..."	self-assessment	Teacher evaluation	final grade

bacteria.

There is practically no place on earth where bacteria do not occur. 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 a few tens of thousands of years ago. Especially a lot of 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 viewed under a microscope, because. they are very small and 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, while most are much smaller.

When examining bacteria under a microscope, scientists noticed that bacteria are not just similar to each other, they have the ability to have several appearances, that is, forms bacteria.

Bacteria shape.

spherical (cocci)

rod-shaped (bacilli)

convoluted (vibrios)

spiral-like (spirilla)

spirochetes (6-10 turns)

streptococci (chain of cocci)

staphylococci (bunches of cocci)

The simplest form of bacteria is a ball, it is called coccus, which means "berry" in translation. During reproduction, cocci sometimes remain connected in pairs, such a connection is called diplococcus, with a larger number, a chain is formed, which is called streptococcus. When cocci are connected in clusters, they get the name staphylococcus aureus. Elongated cocci are called sticks, if they have a curved shape, then they are called vibrio. Spiral long bacteria are called - spirilla or spirochete. There are other forms, but these are the most important.

The shape determines such abilities of bacteria as attachment to the surface, mobility, absorption of nutrients. In addition, bacteria can live in colonies.

bacteria

History of the study of bacteria.

The Dutch naturalist Anthony van Leeuwenhoek in 1676 first saw bacteria in an optical microscope and called them "animalcules".

Christian Ehrenberg in 1828 coined the name "bacteria".

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 determining the causative agent of the disease. In 1905 he was awarded the Nobel Prize for research on tuberculosis.

M. V. Beijerink and S. N. Vinogradsky laid the foundations of general microbiology and the study of the role of bacteria in nature.

bacteria very prolific . breed bacteria by 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 able to form 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 endure adverse conditions, bacteria have learned to form disputes - special forms of bacteria. They are formed by the drying of bacteria inside their shell, decreasing in size. At the same time, the contents of the cell, shrinking, move away from the shell, round off and form on its surface, being inside the maternal 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 withstand drying, heat and frost, do not die immediately even in boiling water. Spores are easily carried by wind, water, etc. There are many of them in the air and soil. Under favorable conditions, the spore germinates and becomes a viable bacterium. Bacterial spores are adaptations for survival in adverse conditions.

bacteria

The living conditions of bacteria are very diverse.

Type breathing isolated from bacteria aerobes and anaerobes .

Like all living things, most bacteria need 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 need oxygen live on the surface of the soil, in the upper layers of water, in the atmospheric air. Those bacteria for which oxygen is harmful live in the deep layers of the soil, in the silt, in the water column.

bacteria

The vital activity of bacteria can proceed in various temperature conditions. Some of them are able to develop under temperature conditions from - 2 to +75 degrees. Bacteria can live in places where almost no one can survive: boiling geysers, underground oil lakes, acidic lakes where there are no fish. Some bacteria can survive even in space. But the most favorable for most bacteria can be considered a temperature from +4 to +40 degrees. At higher temperatures, many types of bacteria die. To destroy bacteria, they are steamed at a temperature of 120 degrees for 20 minutes. Harmful to bacteria and sunlight.

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 is a special protective shell - cell wall, which is made of a special substance - murein. The liquid part of the cell is called cytoplasm. bacteria prokaryotes , they do not have a nucleus, instead they have a clot of cytoplasm, in which there is a molecule that carries information - a DNA molecule, and is called nucleoid, translates as "similar to the nucleus." flagellum bacteria is necessary for movement, but not all bacteria have a flagellum, not all of them are capable of movement. Not all bacteria have special villi(bacilli are covered with hairs - saws), of which there are two types: some bacteria attach to the necessary surfaces, others serve to transfer information between bacteria. Inside the bacterium is reserve nutrient. Both the cell membrane and the cell membrane are permeable to substances that bacteria need for life, primarily for nutrition. When harmful substances are formed for the bacteria, they are also removed through the shell and membrane, this is how the metabolism of bacteria occurs.

Blitz poll "Do you believe that" (+, -).

	Do you believe that...
	Bacteria are ubiquitous
	They are divided into three groups according to their shape.
	spherical bacteria - cocci
	Bacteria nuclear organisms
	The mode of nutrition is autotrophic and heterotrophic
	Produce spores during reproduction
	The hereditary substance is located in the nucleus
	Respiration aerobic and anaerobic
	The science that studies bacteria is microbiology

Right answers:		Mutual evaluation:

Blitz poll "Do you believe that" (+, -).

	Do you believe that...
	Bacteria are ubiquitous
	They are divided into three groups according to their shape.
	spherical bacteria - cocci
	Bacteria nuclear organisms
	The mode of nutrition is autotrophic and heterotrophic
	Produce spores during reproduction
	The hereditary substance is located in the nucleus
	Respiration aerobic and anaerobic
	The science that studies bacteria is microbiology
	Bacteria discoverer Anthony van Levehoek
Right answers:		Mutual evaluation:

Blitz poll "Do you believe that" (+, -).

	Do you believe that...
	Bacteria are ubiquitous
	They are divided into three groups according to their shape.
	spherical bacteria - cocci
	Bacteria nuclear organisms
	The mode of nutrition is autotrophic and heterotrophic
	Produce spores during reproduction
	The hereditary substance is located in the nucleus
	Respiration aerobic and anaerobic
	The science that studies bacteria is microbiology
	Bacteria discoverer Anthony van Levehoek
Right answers:		Mutual evaluation:

Blitz poll "Do you believe that"

Students complete the answer sheet with tasks (+, -).

	Do you believe that...
	Bacteria are ubiquitous
	They are divided into three groups according to their shape.
	spherical bacteria - cocci
	Bacteria nuclear organisms
	The mode of nutrition is autotrophic and heterotrophic
	Produce spores during reproduction
	The hereditary substance is located in the nucleus
	Respiration aerobic and anaerobic
	The science that studies bacteria is microbiology
	Bacteria discoverer Anthony van Levehoek
Right answers:		Mutual evaluation:

Reception "Mnemotechnics" Expressions on the topic are read out, students do not write anything down. After that, the students reproduce them from memory in a notebook. At the end, the winner is revealed, the one who remembered the most words.

Strategy "Traffic light" formative assessment.

Green card - pleased with myself, did everything in my power and even more

Yellow card - could do better

Red card - not satisfied, did not do everything he could.

Archeology and history are two sciences that are closely intertwined. Archaeological research provides an opportunity to learn about the past of the planet, which, through history, is built in chronological order. Scientists engaged in such research are constantly striving to find more and more ancient forms of living beings that lived on Earth. Studies have shown that bacteria are the oldest microorganisms that ever inhabited the planet.

These microorganisms are constantly under scrutiny, as their role in the process of evolution is almost impossible to overestimate. Discussions on this topic arise very often, but as a result it always turns out that bacteria live on the planet much longer than other creatures, which there are numerous confirmations.

The study of ancient bacteria

The process is actively going on, practically no account is kept of research, and each new discovery becomes a sensation for the whole world. One of the brightest events was the discovery of anaerobic sulfur bacteria that existed 3.4 billion years ago in Australia. The discovery caused a lot of controversy and discussion: even theories about the unearthly origin of microorganisms were used.

There are other types of creatures that can survive for an extremely long time. A good example is certain groups of cyanobacteria, whose age often reaches 2 billion years. Such bacteria are one of the persistent forms of life - creatures capable of evolving without significant changes in their organisms.

Archaeologists manage to find a lot of unique remains of microorganisms, one way or another involved in the process of evolution. Among the oldest organisms were fossil algae and microbes found in the rocks of South Africa: there were found the remains of blue-green algae that existed at least 3.2 billion years ago. This discovery was incredibly important for the scientific community, since these microorganisms were marine, which suggests that the water area was already home to microbes, which later transformed into algae, plants and living beings.

Another important stage in the study of ancient bacteria was the study of groups of microorganisms discovered during excavations in Ontario. The study of the remains showed that these microorganisms existed already two billion years ago. These bacteria were also among the most primitive microorganisms and have already been included in the corresponding section of the taxonomy.

Not so ancient creatures are of considerable interest for history. So, in the central part of Australia, the remains of microorganisms that are part of multicellular algae and other plants were found. The age of these bacteria is within one billion years. The discovery of such units of microorganisms has become very important: relying on their research, scientists can restore the chronology of the evolution of the past and supplement the systematics.

The oldest bacteria existed not only in a single-celled form, but were also part of more complex organisms, for example, green algae, capable of reproducing sexually. Each discovery of this magnitude provides more and more opportunities in the study of living beings, since a variety of forms of organisms that lived in nature arise: any new unit always adds another touch to the genetic diversity of living beings.

The final transition to the differentiation of multicellular creatures occurred about 600 million years ago. Scientists believe that the cause of development was the emergence of various forms of reproduction and the appearance of the first animals, as a result of which nature began to evolve much faster.

Classification and structure of bacteria

In the process of evolution, a large number of the most diverse bacteria appeared. The classification of various microorganisms is carried out by biological systematics, which determines:

the name of a particular type of microorganism;
position in the general classification;
characteristic features of different types of microorganisms.

The structure of bacteria suggests the presence of a hard shell that can preserve the shape of the body and the insides of microorganisms. The shape of the shell is one of the main points that make it possible to classify bacteria: there are spherical, rod-shaped, spiral-shaped and other shapes. Microorganisms are also evaluated by their size: the largest representatives can reach 0.75 mm in length, and the dimensions of the smallest are measured in fractions of micrometers.

The most advanced bacteria have developed flagella that provide movement in space. To improve motor functions, some stretched out into a filamentous shape. About flagellated organisms can be said separately. The main difference between flagellar protozoa and bacteria is the presence of a nucleus in the former. In addition, these microorganisms have chromatophores that allow them to paint themselves in different colors, thereby acquiring similarities with various algae. The main pigment is chlorophyll, which provides the creature's green color, but it is not uncommon to combine with other pigments.

Since external factors can be the cause, many of them have developed a protective function - the formation of spores. When a bacterium is destroyed or its life cycle is terminated, the spores leave the shell and settle in the available space. The production of spores has become an extremely convenient mechanism for most bacteria, since spores perfectly withstand most of the aggressive influences, including temperature shock, lack of liquid or food.

It is amazing: the number of studied species reaches several tens of thousands, which is only a small part of the microorganisms that existed on Earth. A certain difficulty in the study of bacteria is the fact that they are found in almost all multicellular organisms, including algae, terrestrial plants and animals.

The role of bacteria and their development in the life of the planet

The search for the oldest, primordial microorganisms is a very problematic task. From many species of bacteria, practically nothing remains for many millions of years, and they have to be studied based on modern species of living beings, which significantly complicates the systematics. Of course, high-quality equipment and leading minds of specialists allow us to learn a lot, but still, sometimes research runs into an impenetrable wall of time. That is why the number of studied living organisms does not exceed a certain value: there is not enough data for taxonomy.

temperature;
pressure;
wind movement;
other physical and chemical processes.

Nevertheless, according to individual ancient layers, scientists manage to establish many aspects associated with certain organisms. Having certain data on bacteria, algae and other structures that appeared later, one can draw conclusions about the earliest creatures and supplement the systematics.

It is known for certain that the very first organisms required nutrition, therefore they ate organic matter. Over the past millions of years, a large number of microorganism species have changed, and the most persistent subsequently became the basis for the formation of bacteria. Some of them managed to reach the present day almost unchanged. The key feature that provided ancient microorganisms with such high survivability is their ability to absorb nutrients from almost any substance - earth, water, air, etc. Further evolution forced bacteria to develop, as a result of which they appeared, feeding on fermentation, decay and other factors.

The most ancient microorganisms originated and developed in water, since such an environment was the most comfortable for them. This partly explains the diversity of different algae: initially, bacteria were combined into similar multicellular structures. This trend was characterized by almost the entire Precambrian era. Gradually, the smallest organisms united into multicellular organisms, and over time they came to land, which is the reason for the development of terrestrial nature. It is to bacteria that the world can owe its development and constant evolution aimed at adapting to new conditions in a constantly changing world.

Conclusion

Science is constantly moving forward, allowing you to study more and more new types of organisms. In the past, there were a lot of microorganisms, and scientists are hard at work, finding more and more ancient evidence of the life of certain life forms: the remains of any microorganism, whether it be an algae or a complex multicellular organism, are of great value.

The role of these studies is quite high: at some point, science will be able to get to the deepest historical and earthly layers, which will make it possible to learn more about the development of nature on the planet. Bacteria are the oldest microorganisms on the planet, and they can provide a clue to the origin of life, such a discovery will be incredibly important for every person.

Bacteria are the oldest known group of organisms that exist on earth. The age of the oldest bacteria found by archaeologists and paleontologists - the so-called archaebacteria - is more than 3.5 billion years old. The most ancient bacteria lived during the Archeozoic era, when there was nothing else alive on Earth.

The first bacteria possessed the most primitive mechanisms of nutrition and transmission of genetic information and belonged to prokaryotic microorganisms - i.e. devoid of a nucleus.

Eukaryotic or nuclear bacteria with a higher degree of organization of genetic material appeared on the planet only 1.4 billion years ago.

Bacteria became the oldest forms of life still thriving today, for a number of reasons.

First, due to the primitive structure, microorganisms can "adjust" to all possible conditions of existence. Bacteria now live and multiply both in polar ice and in hot springs with water temperatures over 90 degrees, at any concentration of various chemical compounds. Bacteria can exist both in aerobic (containing a certain level of oxygen) conditions and in anaerobic conditions (without oxygen). Their ways of obtaining energy - from absorbing sunlight to using it as energy for metabolism and reproduction of a wide variety of chemicals, biological structures.

Bacteria are known that decompose oil and other chemical compounds and use this energy for their life activity. The first bacteria possessed the most primitive organs for obtaining energy and simply absorbed chemical substances through ordinary diffusion, which in the bacterial cell underwent chemical reactions accompanied by the release of energy.

Secondly, the elementary mechanisms of reproduction (the simplest option is fission in two), occurring at a very fast pace, increased the number of bacteria at the maximum possible rate, thereby increasing their survival rate and increasing the possibility of mutations in the population of bacterial cells, incl. and beneficial mutations that improved the adaptability of bacterial colonies to existing environmental conditions.

The rapid reproduction and variability of microbial populations ensured their high survival in the aggressive conditions that existed on Earth billions of years ago.

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Bacteria are the most ancient group of organisms that currently exist on Earth. The first bacteria probably appeared more than 3.5 billion years ago and for almost a billion years were the only living creatures on our planet. Since these were the first representatives of wildlife, their body had a primitive structure.

Over time, their structure became more complex, but even today bacteria are considered the most primitive unicellular organisms. Interestingly, some bacteria still retain the primitive features of their ancient ancestors. This is observed in bacteria that live in hot sulfur springs and anoxic silts at the bottom of reservoirs.

Various microbes and bacteria live in the world around us, among which there are both good and bad. Here is a selection of interesting facts about bacteria.

1. The largest bacterium, named Thiomargarita namibiensis, which means "Namibia's gray pearl", was discovered in 1999. Its size in diameter reaches 0.75 millimeters and exceeds the standard point, which has a diameter of 1/12 inch - this equals 0.351 millimeters.

2. The smell that comes from the wet earth after rain is due to the organic substance geosmin. It is produced by actinobacteria and cyanobacteria living on the surface of the earth.

3. The process of evolution of bacteria was so successful in ancient times that their appearance has not changed for a billion years. There were only internal changes. This phenomenon has been called the "Volkswagen Syndrome". The Volkswagen Beetle has become so popular throughout the world that its manufacturers have not changed the appearance of the car for forty years.

4. Considering interesting facts about bacteria, it should be noted that the total weight of bacterial colonies living in the human body is two kilograms.

5. There are crustaceans that feed on bacteria grown on their bodies. At depths of more than 2 km, Kiwa puravida crabs live, which have a second name - yeti crabs. These creatures live near cracks, from which sulfur compounds and methane come out, which are a source of energy for bacteria. The crab actively promotes the growth of bacteria, substituting their colonies on the claws for nutrient flows. At the same time, his movements resemble a dance.

6. The most ancient organism identified by scientists is the thermoacidophiles archibacterium. This type of bacteria exists in hot springs with a high acid content. These bacteria do not live at temperatures below 55 degrees.

7. A study conducted by scientists at the University of Manchester showed that there are significantly more microbes on the surface of a mobile phone than found on a toilet seat or on the sole of a shoe.

8. The unique microbes that live in the intestines of the Japanese provide a more efficient processing of seaweed carbohydrates that are part of the land than people from other regions.

9. Few people know that bacillus and bacterium are one and the same living organism. It’s just that the word “bacillus” has a Latin origin, and the word “bacterium” comes from the Greek language.

10. One of the two kilograms of bacteria living in the human body is located in its intestines. The number of these bacteria greatly exceeds the number of cells in the human body.

11. There are almost 40 thousand different types of bacteria in the human mouth. During a kiss, people can pass on 278 types of bacteria to each other. Of these, 95% are safe.

12. Since the size of the largest of the existing bacteria Thiomargarita namibiensis reaches 0.75 mm in diameter, this allows you to see it even with the naked eye.

13. In the last century, doctors in some countries removed the appendix to all children, without exception. This was explained by the prevention of future inflammation of the appendix. Studies by scientists conducted at the beginning of this century showed that the appendix is not a rudiment. This organ is very important for the immune system, since it is in it that many microorganisms live.

14. During a person's illness, a significant part of the natural flora of his intestines dies. It is then that the body receives a “reinforcement” of microflora from the appendix.

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Lesson topic:

Bacteria are the oldest group of living organisms. General characteristics of bacteria. Differences between bacterial cells and plant cells. Concepts of prokaryotes and eukaryotes.

Lesson objectives:

Educational: know the features of the structure and vital activity of bacteria.

Developing: develop a cognitive interest in biology; skills of comparative-analytical and mental activity. Continue the formation of skills in working with a textbook, workbook, table.

Educational: educate the ability to work in a team and find agreed solutions; education of independence of judgments; fostering a culture of behavior in the classroom.

Equipment: Presentation "Structure of bacteria", "Structure of a plant cell"

During the classes:

I. Org. moment:

II. Call stage. Knowledge update.

These small organisms created life on Earth, carry out the global circulation of substances in nature, and also serve humans. Louis Pasteur called them "the great gravediggers of nature." Who are they?

Teacher: Guys! Name these small organisms.

About 5 billion years ago, the Earth was deserted. Low green clouds (from an excess of chlorine in the air) crawled over the desert expanses without end and without edge, and poured hot rains almost without ceasing. For weeks, months, years, they flooded the plains, gentle hills and smoking hills of volcanoes. The wind roamed the Earth from end to end, meeting only a stone in its path. Only from time to time there was a scream of fiery lavas, hissing and pouring out and solidifying. A cloudy, greenish sun occasionally appeared in the openings of the clouds. It was reflected in small lakes-seas, which could be forded. Millions and millions of years passed before in the early Precambrian, about 3.5 - 3.8 billion years ago, bacteria appeared, and then blue-green algae, producers of free oxygen.

Teacher: Guys! Look at the pictures of the depicted organisms.

On the basis of what features did you classify these organisms as bacteria?

Teacher: Today in the lesson we will get acquainted with unicellular organisms. Open notebooks, write down the number, the topic of the lesson and draw a table:

What do I know?

What did you want to know?

What did you find out?

Teacher: 1. What can you say about these animals?

2. What associations do you have with the word “Bacteria”? ( fill in the "What I know" column.

I . Problem question:

Why are bacteria, being one of the oldest on Earth, having passed a long evolutionary path, are widespread and exist along with highly organized organisms?

Is it possible for the existence of the modern biosphere and man in it without bacteria?

Student : In order to answer the question, it is necessary to study the general characteristics of bacteria.

II. The stage of comprehension.

Teacher: Write down everything you know about bacteria in the first column.

Who are bacteria?

What science studies them?

bacteria- primitive unicellular organisms, in the cytoplasm of which there is no formed nucleus. The nuclear substance is distributed throughout the cytoplasm.

Bacteriology The branch of microbiology that deals with the study of bacteria.

What did you want to know? We draw up a structural - logical diagram in the column "What did you want to know?"

Exercise: You will get acquainted with the general characteristics of bacteria yourself by reading the paragraph of the textbook "Bacteria", pp. 7-10, and in order to streamline the information received, draw up a general characteristic of bacteria according to the plan in the column "What did you learn?"

Feature plan:

To which group of living organisms do bacteria belong?

History of the discovery of bacteria.

Where are bacteria found?

Structure.

reproduction .

What do I know?

What did you want to know?

What did you find out?

unicellular organisms. Distributed everywhere.

Cyanobacteria - blue-green algae. (on the topic Unicellular algae). They cause diseases. They multiply quickly.

Structural and logical scheme:

Systematics Structure

bacteria

Structure Distribution

1. Living organisms are divided into 2 groups:

Non-nuclear - prokaryotes, nuclear - eukaryotes ..

prokaryotes- organisms that do not have a formed nucleus, the molecule of organic matter is not separated from the cytoplasm, but is attached to the cell membrane. Bacteria belong to this group.

eukaryotes organisms that have a well-formed nucleus with a nuclear envelope. The group of eukaryotes includes plants, fungi, animals, including humans.

2.. Bacteria were first seen through an optical microscope and described by the Dutch naturalist Anthony 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 the disease (Koch's postulates). In 1905 he was awarded the Nobel Prize for tuberculosis research.

3. Bacteria are ubiquitous: in the air, water bodies, soil, food, in living organisms, in the thickness of the Atlantic glaciers, hot deserts, hot springs.

4.. Draw in a notebook.

5. Reproduction:

Bacteria reproduce by simple division in two. Every 20 minutes, under favorable conditions, the number of some bacteria can double.

Under unfavorable conditions (with a lack of food, moisture, sudden changes in temperature), the cytoplasm of a bacterial cell, shrinking, departs from the mother shell, rounds off and forms a new, denser shell inside it on its surface. This bacterial cell is called spore.

Physical education minute

One - rise, stretch,
Two - bend, unbend,
Three - in the hands of 3 claps,
Head 3 nods,
Four - arms wider,
Five - wave your hands,
Six - sit down at the desk again.

Class task:

1. Compare the structure of a plant cell and a bacterial cell. (Presentation “The structure of a plant cell and the structure of a bacterial cell)

2. If, for example, only one such bacterium has entered the human body, then after 12 hours there may already be several billion of them. With such a reproduction rate, the offspring from one bacterium can form a mass in 5 days that can fill all the seas and oceans in 5 days.

But that doesn't happen. Why do you think?(It turns out that most bacteria die under the action of sunlight, drying, lack of

food, heating, under the influence of disinfectants. This is also the basis for the methods of combating bacteria.)

Teacher: Have we answered the problematic question posed at the beginning of the lesson?

Students formulate conclusions for the lesson.

1. Bacteria are primitive unicellular organisms with microscopic dimensions.

2. Bacteria are ubiquitous.

3.. They multiply very quickly under favorable conditions.

6. Spore - a bacterial cell with a dense shell.

IV. Reflection.

What are the structural features of a bacterial cell?

Who is Louis Pasteur, what discoveries did he make?

What properties of bacteria and algae are characteristic of cyanobacteria?

- What is a bacterial spore and what is it used for?

Drawing up a syncwine on the topic "Bacteria".

5. Homework. §2.

Prepare reports based on Internet materials and additional literature on the topics: “Nodule bacteria”, “Cyanobacteria”, “Lactic acid bacteria”, “Pathogenic bacteria”.

Bacteria is the most ancient organism on earth, as well as the simplest in its structure. It consists of only one cell, which can only be seen and studied under a microscope. A characteristic feature of bacteria is the absence of a nucleus, which is why bacteria are classified as prokaryotes.

Some species form small groups of cells; such clusters may be surrounded by a capsule (sheath). The size, shape, and color of bacteria are highly dependent on the environment.

In terms of shape, bacteria are divided into: rod-shaped (bacilli), spherical (cocci) and convoluted (spirilla). There are also modified ones - cubic, C-shaped, star-shaped. Their sizes range from 1 to 10 microns. Certain types of bacteria can actively move with the help of flagella. The latter sometimes exceed the size of the bacterium itself twice.

Types of bacteria forms

For movement, bacteria use flagella, the number of which is different - one, a pair, a bundle of flagella. The location of the flagella is also different - on one side of the cell, on the sides, or evenly distributed over the entire plane. Also, one of the ways of movement is considered to be sliding due to the mucus that the prokaryote is covered with. Most have vacuoles inside the cytoplasm. Adjusting the capacity of the gas in the vacuoles helps them move up or down in the liquid, as well as move through the air channels of the soil.

Scientists have discovered more than 10 thousand varieties of bacteria, but according to the assumptions of scientific researchers, there are more than a million species of them in the world. The general characteristics of bacteria makes it possible to determine their role in the biosphere, as well as to study the structure, types and classification of the bacterial kingdom.

habitats

The simplicity of the structure and the speed of adaptation to environmental conditions helped bacteria to spread over a wide range of our planet. They exist everywhere: water, soil, air, living organisms - all this is the most acceptable habitat for prokaryotes.

Bacteria have been found both at the south pole and in geysers. They are on the ocean floor, as well as in the upper layers of the Earth's air shell. Bacteria live everywhere, but their number depends on favorable conditions. For example, a large number of bacterial species live in open water bodies, as well as in the soil.

Structural features

A bacterial cell is distinguished not only by the fact that it does not have a nucleus, but also by the absence of mitochondria and plastids. The DNA of this prokaryote is located in a special nuclear zone and has the form of a nucleoid closed in a ring. In bacteria, the cell structure consists of a cell wall, a capsule, a capsule-like membrane, flagella, pili, and a cytoplasmic membrane. The internal structure is formed by the cytoplasm, granules, mesosomes, ribosomes, plasmids, inclusions and nucleoid.

The bacterial cell wall performs the function of defense and support. Substances can freely flow through it due to permeability. This shell contains pectin and hemicellulose. Some bacteria secrete a special mucus that can help protect against drying out. Mucus forms a capsule - a polysaccharide in chemical composition. In this form, the bacterium is able to tolerate even very high temperatures. It also performs other functions, for example, sticking to any surfaces.

On the surface of the bacterial cell are thin protein villi - pili. There may be a large number of them. Pili help the cell to transfer genetic material, and also provide adhesion to other cells.

Under the plane of the wall is a three-layer cytoplasmic membrane. It guarantees the transport of substances, and also plays a significant role in the formation of spores.

The cytoplasm of bacteria is 75 percent made from water. The composition of the cytoplasm:

fishsomes;
mesosomes;
amino acids;
enzymes;
pigments;
sugar;
granules and inclusions;
nucleoid.

Metabolism in prokaryotes is possible, both with the participation of oxygen and without it. Most of them feed on ready-made nutrients of organic origin. Very few species are capable of synthesizing organic substances from inorganic ones themselves. These are blue-green bacteria and cyanobacteria, which played a significant role in shaping the atmosphere and saturating it with oxygen.

reproduction

In conditions favorable for reproduction, it is carried out by budding or vegetatively. Asexual reproduction occurs in the following sequence:

The bacterial cell reaches its maximum volume and contains the necessary supply of nutrients.
The cell lengthens, a partition appears in the middle.
Within the cell, a division of the nucleotide occurs.
DNA main and separated diverge.
The cell is divided in half.
Residual formation of daughter cells.

With this method of reproduction, there is no exchange of genetic information, so all daughter cells will be an exact copy of the mother.

The process of reproduction of bacteria in adverse conditions is more interesting. Scientists learned about the ability of bacteria to reproduce sexually relatively recently - in 1946. Bacteria do not have a division into female and germ cells. But they have different DNA. Two such cells, when approaching each other, form a channel for the transfer of DNA, an exchange of sites occurs - recombination. The process is quite long, the result of which are two completely new individuals.

Most bacteria are very difficult to see under a microscope because they do not have their own color. Few varieties are purple or green due to their content of bacteriochlorophyll and bacteriopurpurine. Although if we consider some colonies of bacteria, it becomes clear that they release colored substances into the environment and acquire a bright color. In order to study prokaryotes in more detail, they are stained.

Classification

The classification of bacteria can be based on indicators such as:

Form
way to travel;
way to get energy;
waste products;
degree of danger.

Bacteria symbionts live in partnership with other organisms.

Bacteria saprophytes live on already dead organisms, products and organic waste. They contribute to the processes of decay and fermentation.

Decay cleanses nature of corpses and other wastes of organic origin. Without the process of decay, there would be no cycle of substances in nature. So what is the role of bacteria in the cycling of matter?

Decay bacteria are an assistant in the process of breaking down protein compounds, as well as fats and other compounds containing nitrogen. Having carried out a complex chemical reaction, they break bonds between the molecules of organic organisms and capture protein molecules, amino acids. Splitting, the molecules release ammonia, hydrogen sulfide and other harmful substances. They are poisonous and can cause poisoning in humans and animals.

Decay bacteria multiply rapidly in favorable conditions for them. Since these are not only beneficial bacteria, but also harmful ones, in order to prevent premature decay in products, people have learned to process them: dry, pickle, salt, smoke. All of these treatments kill bacteria and prevent them from multiplying.

Fermentation bacteria with the help of enzymes are able to break down carbohydrates. People noticed this ability in ancient times and use such bacteria to make lactic acid products, vinegars, and other food products to this day.

Bacteria, working in conjunction with other organisms, do very important chemical work. It is very important to know what types of bacteria are and what benefits or harm they bring to nature.

Significance in nature and for man

The great importance of many types of bacteria (in the processes of putrefaction and various types of fermentation) has already been noted above; fulfillment of a sanitary role on Earth.

Bacteria also play a huge role in the cycle of carbon, oxygen, hydrogen, nitrogen, phosphorus, sulfur, calcium and other elements. Many types of bacteria contribute to the active fixation of atmospheric nitrogen and convert it into an organic form, contributing to an increase in soil fertility. Of particular importance are those bacteria that decompose cellulose, which are the main source of carbon for the vital activity of soil microorganisms.

Sulfate-reducing bacteria are involved in the formation of oil and hydrogen sulfide in therapeutic mud, soils and seas. Thus, the layer of water saturated with hydrogen sulfide in the Black Sea is the result of the vital activity of sulfate-reducing bacteria. The activity of these bacteria in soils leads to the formation of soda and soda salinization of the soil. Sulfate-reducing bacteria convert nutrients in rice plantation soils into a form that becomes available to the roots of the crop. These bacteria can cause corrosion of metal underground and underwater structures.

Thanks to the vital activity of bacteria, the soil is freed from many products and harmful organisms and saturated with valuable nutrients. Bactericidal preparations are successfully used to combat many types of insect pests (corn borer, etc.).

Many types of bacteria are used in various industries to produce acetone, ethyl and butyl alcohols, acetic acid, enzymes, hormones, vitamins, antibiotics, protein and vitamin preparations, etc.

Without bacteria, processes are impossible in tanning leather, drying tobacco leaves, making silk, rubber, processing cocoa, coffee, urinating hemp, flax and other bast-fiber plants, sauerkraut, sewage treatment, leaching metals, etc.

Passport of project work.

Project name " Bacteria in our life

Project leader - I.A. Shtreker, teacher of biology and chemistry, MBOU secondary school No. 24, town. Kaz.

The subject of study is biology, within which the work is carried out.

Academic disciplines are close to the topic of the project: history, informatics.

Age 13

Project Type: Research

Target

Empirically confirm the importance of our living conditions for the growth and development of bacteria.

Tasks

1. To study the effect of bacteria on dairy products;

2. To 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 life." I decided to make this presentation and defend it at a school environmental conference.

My work plan:

Topic selection.

Search for information

Study

Making a presentation

5. Protection of the project.

What are microbes?! Where did they come from and what do they look like? We hear on TV and on the 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 get on objects, clothes, hands, food , in the mouth, intestines.

The size of microbes is so small that they are measured in thousandths and even millionths of a millimeter. Microbes can only be seen with an optical or electron microscope. They can cause various diseases, poisonings. 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 even exist?

In total, scientists counted 500 species of bacteria in the samples.

Hypothesis: I want to make sure there are bacteria on our hands. And do you really need to wash your hands to protect yourself from bacteria?

Relevance: Do bacteria exist on our hands?

Problem: ways to protect against bacteria.

Discovery history

Seeing the microbe became possible after the invention of the microscope. The first to see and describe microorganisms was the Dutch naturalist Anthony van Leeuwenhoek (1632-1723), who designed a microscope that magnified up to 300 times. Through a microscope, he examined everything that came to hand: water from a pond, various infusions, blood, plaque, and much more. In the objects he viewed, he found the smallest creatures, which he called "living animals". He established spherical, rod-shaped and convoluted forms of microbes. Leeuwenhoek's discovery laid the foundation for the emergence of microbiology.

The French chemist Louis Pasteur (1822-1895) was the first to study bacteria and their properties. He proved that microbes are the cause of fermentation and decay, capable of causing disease.

Great merit in the development of microbiology II Mechnikov (1845-1916). He 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 doctrine of the body's immunity to infectious diseases (immunity).

Habitat

Bacteria are the very first living things that appeared on our planet.
Bacteria live almost everywhere where there is water, including hot springs, the bottom of the world's oceans, and also deep inside the earth's crust. They are an important link in the 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. Especially a lot of them in the soil. One 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 airing before the start of the lesson, bacteria are 13 times less than before airing.

1.3. What are bacteria. Bacteria are both beneficial and harmful.

Many animals need bacteria to live. 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 that live in special sections of the stomach and intestines help animals digest fiber.

We know putrefactive bacteria spoil food. But this harm that they bring to man is nothing compared to the benefits that 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.

Yogurt, cheese, sour cream, butter, kefir, sauerkraut, pickled vegetables - all these products would not exist if there were no lactic acid bacteria. Man has been using them since ancient times. By the way, curdled milk is digested 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.

The structure of bacteria

The structure depends on the mode of life and nutrition of the microorganism. Bacteria can be rod-shaped (bacilli), spherical (cocci) and spiral (spirilla, vibrios, spirochetes) shape.

How do they infect us?? Contagious (infectious) diseases have been known since ancient times. The most severe of them (plague, cholera, smallpox) often took on a mass distribution, caused a wholesale pestilence, as a result of which flourishing cities turned into vast cemeteries.

In addition to these especially dangerous infections, there are still many other infectious diseases that can cause epidemics - these are dysentery, typhoid fever and paratyphoid fever, typhus and relapsing fever, brucellosis, these diseases arise through dirty products 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 excreted by a sick organism from the affected respiratory tract (nose, pharynx, bronchi, lungs). When a sick person speaks, coughs, sneezes, he throws out the smallest splashes into the surrounding air - droplets of infected sputum or nasal mucus. In this way, microbes-causative agents easily penetrate, along with contaminated air, into the nose, throat, and lungs of healthy people, where the further development of the disease occurs. Such an "air" or "drip" 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 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, do the students wash their hands?

Result:

When asked 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 wash 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 in order to maintain your health.

My experiences.

I washed, peeled the potato tuber, cut it into 2 shares, soaked it in a soda solution, cooked it, cooled it. I made 2 glass jars with lids sterile, put the potato share in jar No. 1 with dirty hands, and the potato share in No. 2 jar washed with soapy hands. Banks put in a warm place. As a result, after 4 days, the potatoes that I took with dirty hands were densely covered with bacterial colonies, and in jar No. 2, the potatoes were partially covered with colonies.

Conclusion: there are a lot of bacteria on dirty hands.

Experience No. 2 (with milk)

Obtaining curdled milk from milk.

I took 1 glass of fresh milk, put it in a warm place the next day I got yogurt

Getting sour cream from cream.

I took 1 glass of cream and put it in a warm place, a day later I got sour cream

Conclusion: In this way, I was convinced that beneficial bacteria help make many delicious foods.

1. Introduction

2. Characterization of bacteria

3. History of the discovery of microorganisms

4. Forms of bacteria

5. The structure of bacteria

6. Spread of bacteria

7. Feeding Bacteria

8. Reproduction of bacteria

9. Spore formation

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). known about 10,000 types of bacteria
Bacteria are relatively simple microscopic unicellular organisms.
divided by two departments: Drobyanki and Cyanobacteria (Blue-green algae)

History of the discovery of bacteria

The first person to see microorganisms was a Dutchman

Anthony van Leeuwenhoek:

“April 24, 1676, I looked at the water ... and with great surprise I saw in it a huge number of the smallest living creatures ...”

Anthony van Leeuwenhoek

Characterization of bacteria

The oldest 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)
They have a different shape
Have different ways of eating
Distributed everywhere

Shapes of bacteria

rod-shaped

Group name

spherical

curved

tuberculosis

Spiral

vibrios

Spirilla

Spiral

rod-shaped

Most bacteria are colorless.

Few are colored purple or green

spherical shape

The structure of bacteria

Available dense cellular membrane covered with mucous membrane capsule
typical no core - there is a nuclear substance, 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 cu. see water near cities has up to 400,000 bacteria
There are especially many bacteria in fertile soil, in 1 cu. see soil over a million bacteria

Bacteria nutrition

Most bacteria feed on ready-made organic substances - heterotrophs:

- saprophytes

- symbionts

Some bacteria are able to create organic substances from inorganic ones - autotrophs:

- photoautotrophs ( cyanobacteria)

- chemoautotrophs

Metabolism:

Live in an oxygen environment aerobes
In anoxic - live anaerobes

Reproduction of bacteria

Reproduce by dividing one cell into two (fragmentation)
Under favorable conditions, the division process occurs every 20 to 30 minutes.
Restrain the growth of bacteria:

sunlight

Lack of food

Heat

Disinfectants

Interspecies struggle

Stages of crushing bacteria

Spore formation

Under unfavorable conditions, the bacterium turns into a spore
The dispute persists for a very long time
In the form of a spore, bacteria can be spread by wind, water
Once in favorable conditions, spores germinate and become viable bacteria.

Formation of bacterial spores

The role of bacteria in nature

An important link in matter cycle in nature
Break down complex substances into simple ones, which are again used by plants
bacteria rotting decompose the corpses of animals and dead plants , form humus - orderlies of the planet

soil bacteria turn humus into minerals
nitrogen fixing bacteria absorb nitrogen air, form nitrogen compounds in the soil (symbiosis with leguminous plants