Diagram of the structure of plant and animal cells. General structure of animal and plant cells. No cell wall, no chloroplasts, no vacuoles
Cell- the structural unit of a living organism. As a functional unit, it has all the properties of a living thing: it breathes, eats, it is characterized by metabolism, excretion, irritability, division and self-reproduction of its own kind. Typical plant cell contains chloroplasts and vacuoles; surrounded by a cellulose cell wall.
Chloroplasts- two-membrane green plastids (presence of chlorophyll pigment). Responsible for the process of photosynthesis. In addition to chloroplasts, the plant cell contains yellow-orange or red plastids (chromoplasts) and colorless plastids (leucoplasts).
Vacuole- a cavity that occupies 70-90% of the total volume of an adult cell, separated from the cytoplasm by a membrane (tonoplast). Plant cells are characterized by the presence of a vacuole with cell sap, in which salts, sugars, and organic acids are dissolved. Vacuole regulates turgor cells (internal pressure).
Cytoplasm- the internal environment of the cell, a colorless viscous formation that is in constant motion. The cytoplasm consists of water with substances dissolved in it and organoids.
Cell wall(cell wall) - outside dense, formed by cellulose or fiber, inside the plasma membrane, in the construction of which proteins and fat-like substances participate. Its molecules are assembled into bundles of microfibrils, which are twisted into macro-fibrils. A strong cell wall allows you to maintain internal pressure - turgor.
Nucleus- the carrier of the signs and properties of the cell and the whole organism. The nucleus is separated from the cytoplasm by a two-layer membrane. The nucleus contains chromosomes and nucleoli. The number of chromosomes for a species is constant. The nucleus contains hereditary material - DNA with its associated proteins - histones ( chromatin). The nucleus is filled with nuclear juice (karyoplasm). The nucleus controls the life of the cell. Chromatin contains coded information for protein synthesis in the cell. During division, the hereditary material is represented by chromosomes.
plasma membrane(plasmalemma, cell membrane) surrounding a plant cell consists of two layers of lipids and protein molecules embedded in them. Lipid molecules have polar hydrophilic "heads" and non-polar hydrophobic "tails". This structure provides selective penetration of substances into and out of the cell.
Lysosomes- Membrane bodies containing intracellular digestive enzymes. Digest substances, excess organelles (autophagy) or entire cells (autolysis).
The body of a higher plant is formed by cells that differ from each other in structure and function. Cells that have a common origin and perform their own function form the cloth.
cell vitality
- Movement of the cytoplasm is carried out continuously and promotes the movement of nutrients and air inside the cell.
- Metabolism and energy includes the following processes:
- the entry of substances into the cell;
- the synthesis of complex organic compounds from simpler molecules, which comes with energy costs (plastic exchange);
- splitting, complex organic compounds to simpler molecules, going with the release of energy used to synthesize the ATP molecule (energy metabolism);
- release of harmful decay products from the cell.
- cell reproduction division.
- Growth cells - an increase in cells to the size of the mother cell.
- Development cells - age-related changes in the structure and physiology of the cell.
Scheme. A typical plant cell.
Living things have a cellular structure similar for all species. However, each kingdom has its own characteristics. To learn more about the structure of an animal cell, this article will help, in which we will tell not only about the features, but also introduce the functions of organelles.
A complexly organized animal organism consists of a large number of tissues. The shape and purpose of the cell depends on the type of tissue in which it is included. Despite their diversity, it is possible to identify common properties in the cellular structure:
- membrane consists of two layers that separate the content from the external environment. In its structure, it is elastic, so the cells can have a variety of shapes;
- cytoplasm located inside the cell membrane. It is a viscous liquid that is constantly moving;
Due to the movement of the cytoplasm inside the cell, various chemical processes and metabolism take place.
- nucleus - has a large size, compared with plants. It is located in the center, inside it there is a nuclear juice, a nucleolus and chromosomes;
- mitochondria consist of many folds - cristae;
- endoplasmic reticulum has many channels, through which nutrients enter the Golgi apparatus;
- a set of tubules called golgi apparatus , accumulates nutrients;
- lysosomes regulate the amount of carbohydrates and other nutrients;
- ribosomes located around the endoplasmic reticulum. Their presence makes the network rough, the smooth surface of the ER indicates the absence of ribosomes;
- centrioles - special microtubules that are absent in plants.
Rice. 1. The structure of an animal cell.
Scientists have discovered the presence of centrioles recently. Since they can be seen and studied only with the help of an electron microscope.
Functions of cell organelles
Each organoid performs certain functions, their joint work makes up a single cohesive organism. For example:
- cell membrane ensures the transport of substances into and out of the cell;
- inside the nucleus is the genetic code that is passed down from generation to generation. Exactly nucleus regulates the work of other cell organelles;
- the energy stations of the body are mitochondria . It is here that ATP is formed, during the breakdown of which ATP is released a large number of energy.
Rice. 2. The structure of mitochondria
- on the walls golgi apparatus fats and carbohydrates are synthesized, which are necessary for building membranes of other organelles;
- lysosomes break down unnecessary fats and carbohydrates, as well as harmful substances;
- ribosomes synthesize protein;
- cell center (centrioles) play an important role in spindle formation during cell mitosis.
Rice. 3. Centrioles.
Unlike a plant cell, an animal cell does not have vacuoles. However, temporary small vacuoles may form, which contain substances to be removed from the body. 4.2. Total ratings received: 630.
Lesson type: combined.
Methods: verbal, visual, practical, problem-search.
Lesson Objectives
Educational: to deepen students' knowledge of the structure of eukaryotic cells, to teach how to apply them in practical classes.
Developing: to improve the ability of students to work with didactic material; develop students' thinking by offering tasks for comparing prokaryotic and eukaryotic cells, plant cells and animal cells with the identification of similar and distinctive features.
Equipment: poster "The structure of the cytoplasmic membrane"; task cards; handout (the structure of a prokaryotic cell, a typical plant cell, the structure of an animal cell).
Intersubject communications: botany, zoology, human anatomy and physiology.
Lesson plan
I. Organizational moment
Check readiness for the lesson.
Checking the list of students.
Presentation of the topic and objectives of the lesson.
II. Learning new material
Division of organisms into pro- and eukaryotes
The shape of the cells is extremely diverse: some are rounded, others look like stars with many rays, others are elongated, etc. Cells are also different in size - from the smallest, hardly distinguishable in a light microscope, to those perfectly visible to the naked eye (for example, fish and frog eggs).
Any unfertilized egg, including giant fossilized dinosaur eggs that are kept in paleontological museums, were also once living cells. However, if we talk about the main elements internal structure all cells are similar.
prokaryotes (from lat. pro- before, before, instead of and Greek. karyon- nucleus) - these are organisms whose cells do not have a nucleus limited by a membrane, i.e. all bacteria, including archaebacteria and cyanobacteria. The total number of species of prokaryotes is about 6000. All the genetic information of a prokaryotic cell (genophore) is contained in a single circular DNA molecule. Mitochondria and chloroplasts are absent, and the functions of respiration or photosynthesis, which provide the cell with energy, are performed by the plasma membrane (Fig. 1). Prokaryotes reproduce without a pronounced sexual process by dividing in two. Prokaryotes are able to carry out a number of specific physiological processes: they fix molecular nitrogen, carry out lactic acid fermentation, decompose wood, and oxidize sulfur and iron.
After an introductory conversation, students consider the structure of a prokaryotic cell, comparing the main features of the structure with the types of eukaryotic cells (Fig. 1).
eukaryotes - These are higher organisms that have a clearly defined nucleus, which is separated from the cytoplasm by a membrane (karyomembrane). Eukaryotes include all higher animals and plants, as well as unicellular and multicellular algae, fungi and protozoa. Nuclear DNA in eukaryotes is enclosed in chromosomes. Eukaryotes have cellular organelles limited by membranes.
Differences between eukaryotes and prokaryotes
- Eukaryotes have a real nucleus: the genetic apparatus of a eukaryotic cell is protected by a shell similar to the shell of the cell itself.
– Organelles included in the cytoplasm are surrounded by a membrane.
The structure of plant and animal cells
The cell of any organism is a system. It consists of three interconnected parts: membrane, nucleus and cytoplasm.
In the study of botany, zoology and human anatomy, you have already become familiar with the structure various types cells. Let's briefly review this article.
Exercise 1. Determine from Figure 2 which organisms and tissue types correspond to the cells under the numbers 1-12. What is the reason for their shape?
The structure and functions of organelles of plant and animal cells
Using figures 3 and 4 and using the Biological Encyclopedic Dictionary and textbook, students complete the table comparing animal and plant cells.
Table. The structure and functions of organelles of plant and animal cells
cell organelles |
The structure of organelles |
Function |
Presence of organelles in cells |
|
plants |
animals |
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Chloroplast |
It is a type of plastid |
Colors plants in green color where photosynthesis takes place |
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leukoplast |
The shell consists of two elementary membranes; internal, growing into the stroma, forms a few thylakoids |
Synthesizes and accumulates starch, oils, proteins |
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Chromoplast |
Plastids with yellow, orange and red color, the color is due to pigments - carotenoids |
Red, yellow color of autumn leaves, juicy fruits, etc. |
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Occupies up to 90% of the volume of a mature cell, filled with cell sap |
Maintenance of turgor, accumulation of reserve substances and metabolic products, regulation of osmotic pressure, etc. |
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microtubules |
Composed of the protein tubulin, located near the plasma membrane |
Participate in the deposition of cellulose on cell walls, the movement of various organelles in the cytoplasm. During cell division, microtubules form the basis of the division spindle structure. |
||
Plasma membrane (CPM) |
Consists of a lipid bilayer permeated with proteins immersed to various depths |
Barrier, transport of substances, communication between cells |
||
Smooth EPR |
System of flat and branching tubules |
Carries out the synthesis and release of lipids |
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Rough EPR |
It got its name because of the many ribosomes on its surface. |
Synthesis of proteins, their accumulation and transformation for release from the cell to the outside |
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Surrounded by a double nuclear membrane with pores. The outer nuclear membrane forms a continuous structure with the ER membrane. Contains one or more nucleoli |
Carrier of hereditary information, center of regulation of cell activity |
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cell wall |
Composed of long cellulose molecules arranged in bundles called microfibrils |
Outer frame, protective shell |
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Plasmodesmata |
Tiny cytoplasmic channels that pierce cell walls |
Unite protoplasts of neighboring cells |
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Mitochondria |
ATP synthesis (energy storage) |
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golgi apparatus |
Consists of a stack of flat sacs - cisterns, or dictyosomes |
Synthesis of polysaccharides, formation of CPM and lysosomes |
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Lysosomes |
intracellular digestion |
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Ribosomes |
Composed of two unequal subunits |
Site of protein biosynthesis |
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Cytoplasm |
Consists of water with a large amount of dissolved substances containing glucose, proteins and ions |
It contains other organelles of the cell and all processes of cellular metabolism are carried out. |
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Microfilaments |
Actin fibers are usually arranged in bundles near the surface of cells |
Involved in cell motility and reshaping |
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Centrioles |
May be part of the mitotic apparatus of the cell. A diploid cell contains two pairs of centrioles |
Participate in the process of cell division in animals; in zoospores of algae, mosses and in protozoa they form basal bodies of cilia |
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microvilli |
protrusions of the plasma membrane |
Increase the outer surface of the cell, microvilli together form the border of the cell |
conclusions
1. The cell wall, plastids and the central vacuole are inherent only in plant cells.
2. Lysosomes, centrioles, microvilli are present mainly only in the cells of animal organisms.
3. All other organelles are characteristic of both plant and animal cells.
The structure of the cell membrane
The cell membrane is located outside the cell, delimiting the latter from the external or internal environment of the body. It is based on the plasmalemma (cell membrane) and the carbohydrate-protein component.
Cell wall functions:
- maintains the shape of the cell and gives mechanical strength to the cell and the organism as a whole;
- protects the cell from mechanical damage and the ingress of harmful compounds into it;
- performs recognition of molecular signals;
- regulates the exchange of substances between the cell and the environment;
- carries out intercellular interaction in a multicellular organism.
Cell wall function:
- represents an external frame - a protective shell;
- provides transport of substances (water, salts, molecules of many organic substances pass through the cell wall).
The outer layer of animal cells, unlike the cell walls of plants, is very thin and elastic. It is not visible under a light microscope and consists of a variety of polysaccharides and proteins. The surface layer of animal cells is called glycocalyx, performs the function of a direct connection of animal cells with the external environment, with all the substances surrounding it, does not play a supporting role.
Under the glycocalyx of the animal and cell wall of the plant cell, there is a plasma membrane that borders directly on the cytoplasm. The plasma membrane contains proteins and lipids. They are arranged in an orderly manner due to various chemical interactions with each other. Lipid molecules in the plasma membrane are arranged in two rows and form a continuous lipid bilayer. Protein molecules do not form a continuous layer, they are located in the lipid layer, plunging into it at different depths. Molecules of proteins and lipids are mobile.
Functions of the plasma membrane:
- forms a barrier that separates the internal contents of the cell from the external environment;
- provides transport of substances;
- provides communication between cells in the tissues of multicellular organisms.
Entry of substances into the cell
The surface of the cell is not continuous. In the cytoplasmic membrane there are numerous tiny holes - pores through which, with or without the help of special proteins, ions and small molecules can penetrate into the cell. In addition, some ions and small molecules can enter the cell directly through the membrane. The entry of the most important ions and molecules into the cell is not passive diffusion, but active transport that requires energy. Transport of substances is selective. The selective permeability of the cell membrane is called semipermeability.
way phagocytosis inside the cell enter: large molecules of organic substances, such as proteins, polysaccharides, food particles, bacteria. Phagocytosis is carried out with the participation of the plasma membrane. In the place where the surface of the cell comes into contact with a particle of some dense substance, the membrane flexes, forms a recess and surrounds the particle, which in the "membrane capsule" is immersed inside the cell. A digestive vacuole is formed, and the nutrients that enter the cell are digested in it. organic matter.
By phagocytosis, amoeba, ciliates, animal and human leukocytes feed. Leukocytes absorb bacteria, as well as a variety of solid particles that accidentally enter the body, thus protecting it from pathogenic bacteria. The cell wall of plants, bacteria and blue-green algae prevents phagocytosis, and therefore this pathway of substances entering the cell is not realized in them.
Liquid droplets containing various substances in a dissolved and suspended state also penetrate into the cell through the plasma membrane. This phenomenon was called pinocytosis. The process of fluid absorption is similar to phagocytosis. A drop of liquid is immersed in the cytoplasm in a "membrane package". Organic substances that enter the cell along with water begin to be digested under the influence of enzymes contained in the cytoplasm. Pinocytosis is widespread in nature and is carried out by the cells of all animals.
III. Consolidation of the studied material
What two large groups are all organisms divided into according to the structure of the nucleus?
What organelles are found only in plant cells?
What organelles are found only in animal cells?
What is the difference between the structure of the cell wall of plants and animals?
What are the two ways substances enter the cell?
What is the importance of phagocytosis for animals?
Different eukaryotic cells are structurally similar. But along with the similarities between the cells of organisms of various kingdoms of living nature, there are noticeable differences. They concern both structural and biochemical features.
The figures show a schematic and three-dimensional image of animal and plant cells with the location of organelles and inclusions in them.
Figure 10 - Schemes of the structure of an animal cell.
The cytoplasm of a cell contains a number of tiny structures that perform a variety of functions. These cell structures bounded by membranes are called organelles. The nucleus, mitochondria, lysosomes, chloroplasts are cellular organelles. Organelles can be separated from the cytosol by a single or double layer membrane.
The main function of the membrane is that various substances move through it from cell to cell. Thus, the exchange of substances between cells and intercellular substance is carried out. The plant cell also has a rigid cell wall above the membrane. The cell walls of neighboring cells are separated by a middle plate, and for the implementation of metabolism in the cell walls there is a system of holes - plasmodesm.
Figure 11 shows the structure of a plant cell.
Figure 11 - Schemes of the structure of a plant cell
A plant cell is characterized by the presence of various plastids, a large central vacuole, which sometimes pushes the nucleus to the periphery, and a cell wall located outside the plasma membrane, consisting of cellulose. In cages higher plants the cell center lacks a centriole found only in algae. The reserve nutrient carbohydrate in plant cells is starch.
So, main organelles of animal and plant cells:
nucleus and nucleolus; ribosomes; endoplasmic reticulum (ER), Golgi apparatus, lysosomes, vacuoles, mitochondria, plastids, cell center (centrioles)
Cytoplasm is an internal semi-liquid environment of cells, limited by the plasma membrane, in which nucleus and other organelles. The most important role of the cytoplasm is to unite all cell structures and ensuring their chemical interaction.
Here are also concentrated various
§ inclusion(temporary formations) - containing insoluble wastes of metabolic processes and reserve nutrients;
§ vacuoles;
§ the thinnest tubes and threads that form the skeleton of the cell.
The composition of the cytoplasm includes all types of organic and inorganic substances. The main substance of the cytoplasm contains a significant amount of proteins and water. The main metabolic processes take place in it, it ensures the interconnection of the nucleus and all organelles and the activity of the cell as a single integral living system. The cytoplasm is constantly moving, flowing inside a living cell, moving with it various substances, inclusions and organelles. This movement is called cyclosis.
A cell is a structural and functional unit of a living organism that carries genetic information, provides metabolic processes, is capable of regeneration and self-reproduction.
There are unicellular individuals and developed multicellular animals and plants. Their vital activity is provided by the work of organs that are built from different tissues. The tissue, in turn, is represented by a collection of cells similar in structure and function.
Cells of different organisms have their own characteristic properties and structure, but there are common components inherent in all cells: both plant and animal.
Organelles common to all cell types
Nucleus- one of the important components of the cell, contains genetic information and ensures its transmission to descendants. Surrounded by a double membrane that isolates it from the cytoplasm.
Cytoplasm- a viscous transparent medium that fills the cell. All organelles are located in the cytoplasm. The cytoplasm consists of a system of microtubules, which provides a clear movement of all organelles. It also controls the transport of synthesized substances.
cell membrane- a membrane that separates the cell from the external environment, ensures the transport of substances into the cell and the excretion of synthesis or vital activity products.
Endoplasmic reticulum- a membrane organelle, consists of tanks and tubules, on the surface of which the synthesis of ribosomes occurs (granular ER). Places where there are no ribosomes form a smooth endoplasmic reticulum. The granular and agranular network are not delimited, but pass into each other and connect with the shell of the nucleus.
Golgi complex- a stack of tanks, flattened in the center and expanded on the periphery. Designed to complete the synthesis of proteins and their further transport from the cell, together with EPS forms lysosomes.
Mitochondria- two-membrane organelles, the inner membrane forms protrusions into the cell - cristae. Responsible for the synthesis of ATP, energy metabolism. Performs a respiratory function (absorbing oxygen and releasing CO 2).
Ribosomes- are responsible for protein synthesis, in their structure there are small and large subunits.
Lysosomes- carry out intracellular digestion, due to the content of hydrolytic enzymes. Break down trapped foreign substances.
Both plant and animal cells have, in addition to organelles, non-permanent structures - inclusions. They appear with an increase in metabolic processes in the cell. They perform a nutritional function and contain:
- Grains of starch in plants, and glycogen in animals;
- proteins;
- lipids are high-energy compounds that are more valuable than carbohydrates and proteins.
There are inclusions that do not play a role in energy exchange, they contain the waste products of the cell. In the glandular cells of animals, inclusions accumulate a secret.
Organelles found only in plant cells
Animal cells, unlike plant cells, do not contain vacuoles, plastids, or cell walls.
cell wall formed from the cell plate, forming the primary and secondary cell membranes.
The primary cell wall occurs in undifferentiated cells. During maturation, a secondary membrane is laid between the membrane and the primary cell wall. In its structure, it is similar to the primary, only it has more cellulose and less water.
The secondary cell wall is equipped with many pores. A pore is a place where there is no secondary wall between the primary membrane and the membrane. The pores are arranged in pairs in adjacent cells. Placed nearby cells communicate with each other by plasmodesma - this is a channel, which is a strand of cytoplasm lined with a plasmolemma. Through it, cells exchange synthesized products.
Functions of the cell wall:
- Maintenance of cell turgor.
- Gives shape to cells, acting as a skeleton.
- Accumulates nutritious foods.
- Protects from external influences.
Vacuoles- organelles filled with cell sap are involved in the digestion of organic substances (similar to the lysosomes of an animal cell). Formed by the joint work of the ER and the Golgi complex. At first, several vacuoles form and function; during cell aging, they merge into one central vacuole.
plastids- autonomous two-membrane organelles, the inner shell has outgrowths - lamellae. All plastids are divided into three types:
- Leucoplasts- non-pigmented formations, capable of storing starch, proteins, lipids;
- chloroplasts- green plastids, contain the pigment chlorophyll, are capable of photosynthesis;
- chromoplasts– crystals orange color due to the presence of the pigment carotene.
Organelles found only in animal cells
The difference between a plant cell and an animal cell is the absence of a centriole, a three-layer membrane, in it.
Centrioles- paired organelles located near the nucleus. They take part in the formation of the spindle of division and contribute to the uniform divergence of chromosomes to different poles of the cell.
plasma membrane- Animal cells are characterized by a three-layer, durable membrane, built from lipids and proteins.
Comparative characteristics of plant and animal cells
Comparative table of animal and plant cells | ||
---|---|---|
Properties | plant cell | animal cage |
The structure of organelles | Membrane | |
Nucleus | Formed, with a set of chromosomes | |
Division | Reproduction of somatic cells by mitosis | |
Organelles | Similar set of organelles | |
cell wall | + | - |
plastids | + | - |
Centrioles | - | + |
Power type | autotrophic | Heterotrophic |
Energy synthesis | With the help of mitochondria and chloroplasts | Only with the help of mitochondria |
Metabolism | The advantage of anabolism over catabolism | Catabolism exceeds synthesis of substances |
Inclusions | Nutrients (starch), salts | Glycogen, proteins, lipids, carbohydrates, salts |
Cilia | Rarely | There is |
Plant cells, thanks to chloroplasts, carry out photosynthesis processes - they convert the energy of the sun into organic substances, animal cells are not capable of this.
Mitotic division of a plant occurs mainly in the meristem, characterized by the presence of an additional stage - preprophase; in the animal body, mitosis is inherent in all cells.
The size of individual plant cells (about 50 µm) exceeds the size of animal cells (about 20 µm).
The relationship between plant cells is carried out due to plasmodesma, animals - with the help of desmosomes.
Vacuoles of a plant cell occupy most of its volume, in animals they are small formations in small quantities.
The cell wall of plants is made up of cellulose and pectin; in animals, the membrane is made up of phospholipids.
Plants are not able to actively move, therefore they have adapted to the autotrophic way of nutrition, synthesizing independently all the necessary nutrients from inorganic compounds.
Animals are heterotrophs and use exogenous organic matter.
The similarity in the structure and functionality of plant and animal cells indicates the unity of their origin and belonging to eukaryotes. Them distinctive features conditioned in a different way life and nutrition.