bacterial cell
It differs from all the others as the most simply constructed.
Cell membrane - main functions - protection and metabolism. The reserve nutrient is unique; it is not found in other living cells - it is the carbohydrate murein.
Membrane - like other living cells, the main function is protection and metabolism.
Cytoplasm is an internal semi-liquid medium that contains nutrients.
Ribosomes - synthesize protein. Mesosomes carry out redox processes. There is no nucleus, there is a nucleoid - circular DNA and RNA. Flagella - provide movement.
Summary of a biology lesson for grade 9 “Structure of the cell.”
Summary
a biology lesson for grade 9
“ Structure of
a cell ” .
1.Lesson type –
combined
2.The purpose of the lesson is
create conditions for understanding and understanding the topic “Cell Structure”, applying knowledge about the general plan of cell structure in characterizing existing artificial models (drawings) and natural objects, checking the level of assimilation of the system of knowledge and skills.
3.Lesson objectives –
1) Identify the essence of the concept “cell is a structural unit of a living thing” (educational task)
2) Study the features of the main parts of the cell (educational task)
3) Learn to build cause-and-effect relationships that reflect the relationship between the structure of the main parts of the cell and their function (developmental task)
4) Learn to identify similarities and differences between animal and plant cells, prokaryotes and eukaryotes (developmental task)
5) Realize the importance of the relationship between various representatives of the kingdoms of the living world as a necessary condition for the sustainable development of the biosphere (educational task)
4. Information and methodological support:
— Program of basic general education in biology for grade 9 “Fundamentals of General Biology” by I. N. Ponomareva, N. M. Chernova
-working programm
—textbook “General Biology” by authors I.N. Ponomareva, O.A. Kornilova and others.
—presentation “Cell structure”
— visual tables “Cell structure. Diversity of cells"
- microscopes
—micropreparations of plant and animal cells
5. Students should know:
1) basic concepts (organelles, cytoplasm, eukaryotes, prokaryotes
2) facts (cell structure, cytoplasm and nucleus, bacterial cells, cellular structure of organisms as evidence of their relationship)
students should be able to:
1) recognize and distinguish prokaryotic and eukaryotic cells by silent patterns
2) recognize and describe on tables the main parts of the cell and organelles
3) name the methods of penetration of substances into the cell, the functions of the main organelles of the cell
4) characterize the main organelles of eukaryotic cells
Lesson summary
| Goals and objectives of the lesson stages | Teacher activities | Student activities | |||||||||||||||||||||||||
| 1 Organizational moment | Greets students | Greetings from teachers | |||||||||||||||||||||||||
| 2 Update Educational purpose - contribute to the formation of an idea of the cell. Developmental goal — Contribute to teaching schoolchildren the ability to identify the essential and non-essential in a concept | “The study of any living organism begins with the cell. Man was able to penetrate the secrets of cellular structure thanks to the works of the English. natural scientist R. Hooke, who introduced the term “cell” into the science of biology * “Using our knowledge from botany, zoology and human biology, let’s try to define the essence of the concept “cell.” Here is the first slide of the presentation, which presents the characteristics of the cell. Try to think and choose from those proposed the one that is the most significant? Presentation slide: | ||||||||||||||||||||||||||
| Try to explain which characteristics are essential and which are not important? Comments on students' answers. *How do you understand what it means, “a cell is a structural and functional unit of a living thing”? | Answer by choosing different options Microscopic cells are an insignificant sign, because there are fairly large cells, for example, an egg They only feed - this is an insignificant sign, because... cells not only feed, but also breathe and multiply. Constantly dividing is also an insignificant sign, because there are cells that divide once in a lifetime, for example, nerve cells structural and functional units of living things are an essential feature Answer: the smallest in the structure of the body | ||||||||||||||||||||||||||
| Motivation | “A cell is the most elementary particle of the whole, if it is a multicellular organism or an independent organism, if it is a unicellular protozoan. A cell is alive, but it is difficult to imagine how it exists in a multicellular organism and as an independent organism in protozoa.” | ||||||||||||||||||||||||||
| Goal setting | What do you think the lesson will be about today? What should we find out? To know? | The purpose of our lesson is to consider the general plan of the cell structure, study the structure and function of the main parts of the cell, and note the distinctive features of animal, plant, and bacterial cells. Writing the lesson topic in a notebook | |||||||||||||||||||||||||
| Primary assimilation of material Developmental goal – create conditions for identifying cause and effect relationships between the structural features of cell parts and the functions performed Educational goal - promote understanding of the main material Educational goal: promote awareness of the importance of knowledge about the relationship of organisms in the evolution of the biosphere | “Cells can be seen under a microscope. Cells vary in size, shape...” Tells with examples, using visual tables and pictures in the textbook. Despite their diversity, cells have much in common. *Pay attention to the second slide, remember what are the main parts in a cell? Slide number 2
|
plant cell
Cell wall - functions are the same, reserve nutrient - carbohydrate - starch, cellulose, etc. Membrane - protection and metabolism, a slight difference - there are plasmodesmata - something like bridges between neighboring cells in multicellular plants. Cytoplasm is an internal semi-liquid medium that contains nutrients. Ribosomes are present, but not many; they synthesize protein. The nucleus is the center of the cell's genetic information. ER (endoplasmic reticulum), smooth (without ribosomes) - ensures the transport of substances, maintains the shape of the cell, rough - ribosomes on it ensure protein synthesis. Cytoplasm is an internal semi-liquid medium that contains nutrients. Chloroplast is an obligatory organelle exclusively of plant cells. Function: photosynthesis. A vacuole is also a plant organelle—a reserve of cell sap. Mitochondria - ATP synthesis - providing the cell with energy. Lysosomes are digestive organelles. Golgi apparatus - produces lysosomes and stores nutrients. Microfilaments are protein threads that serve as “rails” for the movement of certain organelles and are involved in cell division. Microtubules are roughly the same as microfilaments, only thicker.
Cell nutrition. Photosynthesis. Chemosynthesis
All living organisms living on Earth require energy to function. Which is contained in the bonds of organic substances. Organisms obtain organic substances in different ways.
In the 80s XIX century German biologist Wilhelm Pfeffer divided all living organisms according to their method of nutrition. This division has survived to this day.
Wilhelm Pfeffer
Pfeffer noticed that green plants do not need an influx of organic matter from the outside, but synthesize it themselves using solar energy during the process of photosynthesis.
Plants, using the energy of sunlight and absorbing minerals from soil and water, synthesize organic substances. Which are necessary for the construction of new cells and tissues. And the resulting energy is used to carry out all the necessary reactions.
Pfeffer called such organisms autotrophs, which means (from the Greek “auto” - self, “trophe” - food) “self-feeding”.
Some autotrophs obtain energy from sunlight and therefore are called phototrophs. These include plants and cyanobacteria.
And some organisms obtain energy from the energy of oxidation of inorganic substances, and in this case they are called chemotrophs
. These include chemotrophic nitrifying bacteria and others.
Due to the fact that autotrophs themselves synthesize organic substances from inorganic ones, they not only feed themselves, but also feed all other living organisms. Which need ready-made organic matter. Pfeffer called such organisms heterotrophs (ancient Greek ἕτερος - “different”, “different” and τροφή - “food”).
These include all animals that extract the energy they need from ready-made organic substances by eating plants or other animals. Then they transform the resulting organic substances in their bodies into those they need.
This also includes a group of chlorophyll-free parasitic plants that, by clinging to the roots of their fellow plants, absorb the substances they need.
According to the method of obtaining food, heterotrophs are divided into phagotrophs
and
osmotrofov
. Phagotrophs feed by swallowing solid pieces of food (these are animals).
And osmotrophs absorb organic substances in dissolved form through cell walls (this includes fungi and most bacteria).
According to the state of the food source, heterotrophs are divided into biotrophs
and
saprotrophs
.
Biotrophs feed on living organisms and include zoophages
.
They eat animals and phytophages
that eat plants.
For saprotrophs, food is organic matter from dead bodies or animal excretions. There are saprotrophic bacteria, saprotrophic fungi, saprotrophic plants, saprotrophic animals. Among them there are detritivores
(who feed on detritus),
necrophages
(who feed on animal corpses) and
coprophages
(who feed on excrement), etc.
Some living organisms are capable of both autotrophic and heterotrophic nutrition. Such organisms are called mixotrophs
. They are able to synthesize organic substances and feed on ready-made organic compounds. For example, insectivorous plants euglenaceae, etc.
Let us consider in more detail the production of energy by phototrophic organisms.
Plants and some phototrophic organisms are able to capture light quanta that carry energy and convert this energy into the energy of chemical bonds of organic substances.
This process is called photosynthesis.
Photosynthesis
is the synthesis of organic substances from carbon dioxide and water with the obligatory use of light energy. As a result, plants release oxygen and form organic substances for development.
Photosynthesis is a complex multi-stage process that takes place in a plant continuously both day and night. Therefore, photosynthesis reactions are divided into two groups: light phase reactions and dark phase reactions.
First, let's look at the light phase of photosynthesis.
Inorganic substances are used for photosynthesis. Water enters the leaves from the roots along the stems. Minerals are absorbed along with water. The plant obtains carbon dioxide from the air, which is used during the dark phase of photosynthesis.
Where does photosynthesis occur?
The main plant tissue is mesophyll. It consists of two types of cells, which form columnar and spongy parenchyma. Due to the stomata located in the epidermis, the absorption of carbon dioxide and the release of oxygen are ensured.
Columnar parenchyma is located under the epidermis. It faces the light and contains most of the leaf's chloroplasts.
Let's remember the structure of chloroplasts.
Chloroplasts
are green plastids that are found in the cells of photosynthetic eukaryotes. They are designed to capture the energy of sunlight.
And therefore they are the most important organelles of plants. Since the main function of green plastids is photosynthesis.
Chloroplasts have a double-membrane structure. Between the folds of the membranes there are grana. The grains are arranged in such a way that each one receives light. They consist of tilakas
ids.
The inner space of the thylakoid is called the lumen
.
The space between the chloroplast membrane and the thylakoids is called the stroma
.
Chloroplasts are green in color because chlorophylls absorb red and blue-violet light and reflect green.
The thylakoid membrane is actually the place where light-dependent reactions of photosynthesis take place with the participation of chlorophyll.
Similar to mitochondria
The electron transport chain, which we have already discussed in previous lessons, the electron transport chain of photosynthesis consists of many protein complexes and carrier molecules.
The following complexes are distinguished in the chain of carriers.
Photosystem 2, cytochrome B six EP complex, photosystem 1, redox enzyme and
n NADP reductase
and
ATP synthase.
A quantum of light strikes a chlorophyll molecule, which is located in photosystem 2. As a result, the chlorophyll molecules enter an excited state. In this case, 2 electrons are released in photosystem-two. They are transferred to the carrier. Which at the same time captures 2 protons from the stroma.
Photolysis of water
The missing electron from photosystem 2 is replaced by electrons due to the decay or photolysis of water.
The fact is that light energy is also spent on splitting the water molecule.
In this case, hydrogen protons, electrons and free oxygen are formed.
So from two oxidized water molecules one oxygen molecule is formed.
In this case, oxygen is removed into the external environment. Thus, the oxygen we breathe is a product of water oxidation.
And protons (hydrogen) accumulate inside the thylakoid. As a result, the thylakoid membrane, on the one hand, is charged positively due to hydrogen protons, and negatively, on the other, due to electrons.
Thus, the carrier transfers electrons to (BE complex six eff) 2 protons from the carrier are released into the lumen.
And 2 electrons are captured by two protons of the complex and transferred to the next carrier. This is how electrons get to photosystem 1
. Here, electrons are also excited by photons.
Excited electrons move to the next carrier .
Which transfers electrons to the FNR enzyme.
FNR catalyzes the reduction of NADP+ to NADPH (which contains 2 electrons and 2 protons).
The created concentration gradient between the outer and inner sides of the thylakoid membrane is used by ATP synthase to create ATP from ADP.
During this process, approximately 30 times more ATP is produced in the chloroplast than in the mitochondria of the same plants.
Thus, in the light phase, photolysis of water occurs, oxygen is released, ATP synthesis and the formation of NADP H2
Oxygen diffuses into the atmosphere, and ATP and NADP H2 are transported into the stroma of the chloroplast and participate in the processes of the dark phase.
The dark
phase of photosynthesis
occurs in the stroma of the chloroplast. Its reactions do not require light energy, so they occur not only in the light, but also in the dark.
Carbon dioxide, which is contained in the air, is captured by a special substance, five-carbon sugar (ribulose biphosphate )
volume). An enzyme catalyzes this reaction and an unstable six-carbon compound is formed, which immediately breaks down into two molecules of phosphoglyceric acid (PGA).
Then a cycle of reactions occurs in which, through a series of intermediate products, phosphoglycer and
the new acid is converted to glucose. These reactions use the energy of ATP and NADP H2.
In addition to glucose, the process of photosynthesis produces other monomers of complex organic compounds - amino acids, nucleotides, glycerol and fatty acids. Thus, with the help of sunlight, autotrophic organisms, which are called phototrophs, obtain energy.
And some autotrophic organisms - chemotrophs, as we said above, receive energy from the energy of oxidation of inorganic substances. This process is called chemosynthesis.
Chemosynthesis
Organisms that obtain energy from the energy of oxidation of inorganic substances include chemotrophic bacteria: hydrogen bacteria, nitrifying bacteria, sulfur bacteria, etc.).
Substances captured by the bacterium are oxidized, and the resulting energy is used to synthesize complex organic molecules from carbon dioxide and water.
The most important group of chemosynthetic organisms are nitrifying bacteria.
These bacteria living in the soil oxidize ammonia, which is formed during the decay of organic residues, to nitrous acid. Then bacteria of other species of this group oxidize nitrous acid to nitric acid.
Nitrous and nitric acids, which are formed as a result of oxidation, interact with soil minerals to form ammonium salts, which are the most important components of the mineral nutrition of higher plants.
Chemosynthesizing bacteria contribute to the accumulation of minerals in the soil, improve soil fertility, and contribute to wastewater treatment.
And unlike photosynthetic organisms, they are completely independent of sunlight as a source of energy.
