Comparative characteristics of cells. Comparison of features of plant and animal cells

In addition to the features characteristic of prokaryotes and eukaryotes, the cells of plants, animals, fungi and bacteria also have a number of features. Thus, plant cells contain specific organelles - chloroplasts, which determine their ability to photosynthesize, whereas these organelles are not found in other organisms. Of course, this does not mean that other organisms are not capable of photosynthesis, since, for example, in bacteria it occurs on invaginations of the plasma membrane and individual membrane vesicles in the cytoplasm.

Plant cells, as a rule, contain large vacuoles filled with cell sap. They are also found in the cells of animals, fungi and bacteria, but have a completely different origin and perform different functions. The main reserve substance found in the form of solid inclusions in plants is starch, in animals and fungi it is glycogen, and in bacteria it is glycogen or volutin.

One more hallmark of these groups of organisms is the organization of the surface apparatus: the cells of animal organisms do not have a cell wall, their plasma membrane is covered only with a thin glycocalyx, while all others have it. This is entirely understandable, since the way animals feed is associated with capturing food particles in the process of phagocytosis, and the presence of a cell wall would deprive them of this opportunity. The chemical nature of the substance that makes up the cell wall is different in various groups living organisms: if in plants it is cellulose, then in fungi it is chitin, and in bacteria it is murein. Comparative characteristics structure of cells of plants, animals, fungi and bacteria

Differences in the structure of representatives' cells different kingdoms wildlife are shown in the figure.

Chemical composition of the cell. Macro- and microelements. The relationship between the structure and functions of inorganic and organic substances (proteins, nucleic acids, carbohydrates, lipids, ATP) that make up the cell. Role chemical substances in the human cell and body

Chemical composition of the cell

Most chemical elements have been found in living organisms Periodic table elements of D.I. Mendeleev, discovered to date. On the one hand, they do not contain a single element that would not exist in inanimate nature, and on the other hand, their concentrations in bodies inanimate nature and living organisms differ significantly.

These chemical elements form inorganic and organic substances. Despite the fact that inorganic substances predominate in living organisms, it is organic substances that determine their uniqueness chemical composition and the phenomenon of life in general, since they are synthesized mainly by organisms in the process of life and play a vital role in reactions.

Science studies the chemical composition of organisms and the chemical reactions occurring in them. biochemistry.

It should be noted that the content of chemicals in different cells and tissues can vary significantly. For example, if in animal cells proteins predominate among organic compounds, then in plant cells carbohydrates predominate.

Macro- and microelements

About 80 chemical elements are found in living organisms, but only 27 of these elements have their functions in the cell and organism established. The remaining elements are present in small quantities and, apparently, enter the body with food, water and air. The content of chemical elements in the body varies significantly. Depending on their concentration, they are divided into macroelements and microelements.

The concentration of each macronutrients in the body exceeds 0.01%, and their total content is 99%. Macroelements include oxygen, carbon, hydrogen, nitrogen, phosphorus, sulfur, potassium, calcium, sodium, chlorine, magnesium and iron. The first four of the listed elements (oxygen, carbon, hydrogen and nitrogen) are also called organogenic, since they are part of the main organic compounds. Phosphorus and sulfur are also components of a number of organic substances, such as proteins and nucleic acids. Phosphorus is essential for the formation of bones and teeth.

Without the remaining macronutrients it is impossible normal functioning body. Thus, potassium, sodium and chlorine are involved in the processes of cell excitation. Potassium is also necessary for the functioning of many enzymes and the retention of water in the cell. Calcium is found in the cell walls of plants, bones, teeth, and mollusk shells and is required for muscle cell contraction and intracellular movement. Magnesium is a component of chlorophyll, a pigment that ensures photosynthesis occurs. It also takes part in protein biosynthesis. Iron, in addition to being part of hemoglobin, which carries oxygen in the blood, is necessary for the processes of respiration and photosynthesis, as well as for the functioning of many enzymes.

Microelements are contained in the body in concentrations of less than 0.01%, and their total concentration in the cell does not reach 0.1%. Microelements include zinc, copper, manganese, cobalt, iodine, fluorine, etc. Zinc is part of the molecule of the pancreatic hormone - insulin, copper is required for the processes of photosynthesis and respiration. Cobalt is a component of vitamin B12, the absence of which leads to anemia. Iodine is necessary for hormone synthesis thyroid gland, ensuring normal metabolism, and fluoride is associated with the formation of tooth enamel.

Both deficiency and excess or disruption of the metabolism of macro- and microelements lead to the development various diseases. In particular, a lack of calcium and phosphorus causes rickets, a lack of nitrogen - severe protein deficiency, a deficiency of iron - anemia, and a lack of iodine - a violation of the formation of thyroid hormones and a decrease in metabolic rate. A decrease in fluoride intake from water and food largely determines the disruption of tooth enamel renewal and, as a consequence, a predisposition to caries. Lead is toxic to almost all organisms. Its excess causes irreversible damage to the brain and central nervous system which is manifested by loss of vision and hearing, insomnia, renal failure, seizures, and can also lead to paralysis and diseases such as cancer. Acute poisoning lead is accompanied by sudden hallucinations and ends in coma and death.

The lack of macro- and microelements can be compensated by increasing their content in food and drinking water, as well as due to the reception medicines. Thus, iodine is found in seafood and iodized salt, calcium - in eggshells and so on.

The relationship between the structure and functions of inorganic and organic substances (proteins, nucleic acids, carbohydrates, lipids, ATP) that make up the cell. The role of chemicals in the cell and human body

Inorganic substances

Chemical elements cells form various compounds - inorganic and organic. The inorganic substances of the cell include water, mineral salts, acids, etc., and the organic substances include proteins, nucleic acids, carbohydrates, lipids, ATP, vitamins, etc.

Water(H 2 O) is the most common inorganic substance of the cell, which has unique physical and chemical properties. It has no taste, no color, no smell. The density and viscosity of all substances is assessed using water. Like many other substances, water can exist in three states of aggregation: solid (ice), liquid and gaseous (steam). The melting point of water is 0°C, the boiling point is 100°C, however, the dissolution of other substances in water can change these characteristics. The heat capacity of water is also quite high - 4200 kJ/mol K, which gives it the opportunity to take part in thermoregulation processes. In a water molecule, the hydrogen atoms are located at an angle of 105°, while the total electron pairs are pulled away by the more electronegative oxygen atom. This determines the dipole properties of water molecules (one end is positively charged and the other negatively charged) and the possibility of the formation of hydrogen bonds between water molecules. The cohesion of water molecules underlies the phenomenon of surface tension, capillarity and the properties of water as a universal solvent. As a result, all substances are divided into those soluble in water (hydrophilic) and insoluble in it (hydrophobic). Thanks to these unique properties It is predetermined that water has become the basis of life on Earth.

The average water content in the body's cells varies and may change with age. Thus, in a one-and-a-half-month-old human embryo, the water content in the cells reaches 97.5%, in an eight-month-old - 83%, in a newborn it decreases to 74%, and in an adult it averages 66%. However, body cells differ in their water content. So, the bones contain about 20% water, the liver - 70%, and the brain - 86%. In general it can be said that the concentration of water in cells is directly proportional to the metabolic rate.

Mineral salts may be in dissolved or undissolved states. Soluble salts dissociate into ions - cations and anions. The most important cations are potassium and sodium ions, which facilitate the transfer of substances across the membrane and are involved in the occurrence and conduction of nerve impulses; as well as calcium ions, which takes part in contraction processes muscle fibers and blood clotting; magnesium, which is part of chlorophyll; iron, which is part of a number of proteins, including hemoglobin. The most important anions are the phosphate anion, which is part of ATP and nucleic acids, and the carbonic acid residue, which softens fluctuations in the pH of the environment. Ions of mineral salts ensure the penetration of water itself into the cell and its retention in it. If the salt concentration in the environment is lower than in the cell, then water penetrates into the cell. Ions also determine the buffering properties of the cytoplasm, i.e. its ability to maintain a constant slightly alkaline pH of the cytoplasm, despite the constant formation of acidic and alkaline products in the cell.

Insoluble salts(CaCO 3, Ca 3 (PO 4) 2, etc.) are part of the bones, teeth, shells and shells of unicellular and multicellular animals.

In addition, organisms can produce other inorganic compounds, such as acids and oxides. Thus, the parietal cells of the human stomach produce hydrochloric acid, which activates digestive enzyme pepsin, and silicon oxide permeates the cell walls of horsetails and forms the shells of diatoms. IN last years The role of nitric oxide (II) in signaling in cells and the body is also being explored.

Organic matter

Cell theory, its main provisions, role in the formation of the modern natural science picture of the world. Development of knowledge about the cell. Cellular structure organisms, the similarity of the cell structure of all organisms is the basis of the unity of the organic world, evidence of the kinship of living nature

unity of the organic world, cell, cell theory, provisions of the cell theory.

We have already said that a scientific theory is a generalization of scientific data about the object of research. This fully applies to the cell theory created by two German researchers M. Schleiden and T. Schwann in 1839.

The basis of the cellular theory was the work of many researchers who were looking for the elementary structural unit of living things. The creation and development of cell theory was facilitated by the emergence in the 16th century. And further development microscopy.

Here are the main events that became the precursors to the creation of the cell theory:

– 1590 – creation of the first microscope (Jansen brothers);

– 1665 Robert Hooke – the first description of the microscopic structure of the elderberry branch plug (in fact, these were cell walls, but Hooke introduced the name “cell”);

– 1695 Publication by Anthony Leeuwenhoek about microbes and other microscopic organisms, which he saw through a microscope;

– 1833 R. Brown described the nucleus of a plant cell;

– 1839 M. Schleiden and T. Schwann discovered the nucleolus.

Basic provisions of modern cell theory:

1. Everything is simple and complex organisms consist of cells capable of exchange with environment substances, energy, biological information.

2. A cell is an elementary structural, functional and genetic unit of a living thing.

3. Cage – elementary unit reproduction and development of living things.

4. B multicellular organisms cells are differentiated by structure and function. They are organized into tissues, organs and organ systems.

5. The cell is an elementary, open living system, capable of self-regulation, self-renewal and reproduction.

The cell theory developed due to new discoveries. In 1880, Walter Flemming described chromosomes and the processes occurring in mitosis. Since 1903, genetics began to develop. Since 1930, electron microscopy began to develop rapidly, which allowed scientists to study finest structure cellular structures. The 20th century was the century of the flourishing of biology and such sciences as cytology, genetics, embryology, biochemistry, and biophysics. Without the creation of the cell theory, this development would have been impossible.

So, the cell theory states that all living organisms are made up of cells. A cell is the minimal structure of a living thing that has all vital properties - the ability to metabolize, grow, develop, transmit genetic information, self-regulation and self-renewal. The cells of all organisms have similar structural features. However, cells differ from each other in their size, shape and function. An ostrich egg and a frog egg consist of the same cell. Muscle cells have contractility and nerve cells carry out nerve impulses. Differences in the structure of cells largely depend on the functions they perform in organisms. The more complex an organism is, the more diverse its cells are in their structure and functions. Each type of cell has a specific size and shape. Similarities in cell structure various organisms, the commonality of their basic properties confirms the commonality of their origin and allows us to draw a conclusion about the unity of the organic world.

A cell is a unit of structure, vital activity, growth and development of organisms. Diversity of cells. Comparative characteristics of cells of plants, animals, bacteria, fungi

Basic terms and concepts tested in the examination paper: bacterial cells, fungal cells, plant cells, animal cells, prokaryotic cells, eukaryotic cells.

We have already said that cells can differ from each other in shape, structure and function, although the basic structural elements of most cells are similar. Biologists distinguish two large systematic groups of cells - prokaryotic And eukaryotic . Prokaryotic cells do not contain a true nucleus and a number of organelles. (See the section "Cell Structure".) Eukaryotic cells contain the nucleus in which the hereditary apparatus of the body is located. Prokaryotic cells are cells of bacteria and blue-green algae. The cells of all other organisms are eukaryotic.

Any organism develops from a cell. This applies to organisms that were born as a result of both asexual and sexual methods of reproduction. That is why the cell is considered the unit of growth and development of the organism.

Modern taxonomy distinguishes the following kingdoms of organisms: Bacteria, Fungi, Plants, Animals. The basis for this division is the feeding methods of these organisms and the structure of cells.

Bacterial cells have the following structures characteristic of them - a dense cell wall, one circular DNA molecule (nucleotide), ribosomes. These cells lack many organelles characteristic of eukaryotic plant, animal and fungal cells. Based on the way they feed, bacteria are divided into autotrophs, chemotrophs And heterotrophs. Plant cells contain plastids characteristic only of them - chloroplasts, leucoplasts and chromoplasts; they are surrounded by a dense cell wall of cellulose and also have vacuoles with cell sap. All green plants are autotrophic organisms.

Animal cells do not have dense cell walls. They are surrounded by a cell membrane through which the exchange of substances with the environment occurs.

Fungal cells are covered with a cell wall that differs in chemical composition from the cell walls of plants. It contains chitin, polysaccharides, proteins and fats as its main components. The reserve substance of fungal and animal cells is glycogen.

1. Select features characteristic only of plant cells

1) there are mitochondria and ribosomes

2) cell wall made of cellulose

3) there are chloroplasts

4) storage substance – glycogen

5) reserve substance – starch

6) the nucleus is surrounded by a double membrane

2. Select the characteristics that distinguish the kingdom of Bacteria from the rest of the kingdoms of the organic world.

1) heterotrophic mode of nutrition

2) autotrophic method of nutrition

3) the presence of a nucleoid

4) absence of mitochondria

5) absence of a core

6) presence of ribosomes

Chemical organization of the cell. The relationship between the structure and functions of inorganic and organic substances (proteins, nucleic acids, carbohydrates, lipids, ATP) that make up the cell. Justification of the relationship of organisms based on an analysis of the chemical composition of their cells

Basic terms and concepts tested in the examination paper: nitrogenous bases, active center of the enzyme, hydrophilicity, hydrophobicity, amino acids, ATP, proteins, biopolymers, denaturation, DNA, deoxyribose, complementarity, lipids, monomer, nucleotide, peptide bond, polymer, carbohydrates, ribose, RNA, enzymes, phospholipids.

Related information.

These structures, despite the unity of origin, have significant differences.

General plan of cell structure

When considering cells, it is necessary first of all to remember the basic patterns of their development and structure. They have common features structures, and consist of surface structures, cytoplasm and permanent structures - organelles. As a result of vital activity, organic substances called inclusions are deposited in them. New cells arise as a result of the division of maternal cells. During this process, two or more young structures can be formed from one original one, which are an exact genetic copy of the original ones. Cells, uniform in their structural features and functions, are combined into tissues. It is from these structures that the formation of organs and their systems occurs.

Comparison of plant and animal cells: table

On the table you can easily see all the similarities and differences in the cells of both categories.

Main differences

Comparison of plant and animal cell indicates a number of differences in the features of their structure, and therefore life processes. So, despite the unity general plan, their surface apparatus differs in chemical composition. Cellulose, which is part of the cell wall of plants, gives them permanent form. Animal glycocalyx, on the contrary, is a thin elastic layer. However, the most important thing fundamental difference of these cells and the organisms they form lies in the way they feed. Plants have green plastids called chloroplasts in their cytoplasm. On their inner surface there is a complex chemical reaction transformation of water and carbon dioxide into monosaccharides. This process is only possible if there is sunlight and is called photosynthesis. By-product reaction is oxygen.

conclusions

So, we have compared plant and animal cells, their similarities and differences. The common features are the building plan, chemical processes and composition, division and genetic code. At the same time, plant and animal cells are fundamentally different in the way they feed the organisms they form.

Similarities in the structure and metabolic processes of animal, plant, bacterial and fungal cells proves the unity of their origin.

Differences in the structure and metabolic processes of animal, plant, bacterial and fungal cells indicate that these groups of organisms entered different paths of evolution at its earliest stages

The predominance of synthetic processes over processes of energy release is one of the most characteristic features plant metabolism. The primary synthesis of carbohydrates from inorganic substances occurs in plastids. Thus, in animal cells, unlike plant cells, the following plastids are absent: chloroplasts (responsible for the photosynthesis reaction), leucoplasts (responsible for the accumulation of starch) and chromoplasts (give color to the fruits and flowers of plants)

A plant cell has a strong and thick cell wall made of cellulose, but an animal cell does not. In a plant cell, a network of vacuoles is developed, in an animal cell it is poorly developed

An excerpt characterizing comparison of the cell structure of bacteria, plants, animals and fungi

Similarities and differences in the structure of cells of plants, animals and fungi

Similarities in the structure of eukaryotic cells.

Now it is impossible to say with complete certainty when and how life arose on Earth. We also do not know exactly how the first living creatures on Earth ate: autotrophic or heterotrophic. But at present, representatives of several kingdoms of living beings coexist peacefully on our planet. Despite the great difference in structure and lifestyle, it is obvious that there are more similarities between them than differences, and they all probably have common ancestors who lived in the distant Archean era. The presence of common “grandfathers” and “grandmothers” is evidenced by a number of common features in eukaryotic cells: protozoa, plants, fungi and animals. These signs include:

General plan of the cell structure: presence cell membrane, cytoplasm, nucleus, organelles;
- fundamental similarity of metabolic and energy processes in the cell;
- coding of hereditary information using nucleic acids;
- unity of the chemical composition of cells;
- similar processes of cell division.

Differences in the structure of plant and animal cells.

In the process of evolution, due to the unequal conditions of existence of cells of representatives of different kingdoms of living beings, many differences arose. Let's compare the structure and vital activity of plant and animal cells (Table 4).

The main difference between the cells of these two kingdoms is the way they are nourished. Plant cells containing chloroplasts are autotrophs, that is, they themselves synthesize the organic substances necessary for life using light energy during the process of photosynthesis. Animal cells are heterotrophs, i.e., the source of carbon for the synthesis of their own organic substances is organic substances supplied with food. These same nutrients, such as carbohydrates, serve as a source of energy for animals. There are exceptions, such as green flagellates, which are capable of photosynthesis in the light and feed on ready-made food in the dark. organic substances. To ensure photosynthesis, plant cells contain plastids that carry chlorophyll and other pigments.

Since a plant cell has a cell wall that protects its contents and ensures its constant shape, when dividing between daughter cells, a partition is formed, and an animal cell, which does not have such a wall, divides to form a constriction.

Features of fungal cells.

Thus, the separation of fungi into an independent kingdom, numbering more than 100 thousand species, is absolutely justified. Mushrooms originate either from ancient filamentous algae that have lost chlorophyll, i.e., from plants, or from some ancient heterotrophs unknown to us, i.e., animals.

1. How does a plant cell differ from an animal cell?
2. What are the differences in the division of plant and animal cells?
3. Why are mushrooms separated into an independent kingdom?
4. What do they have in common and what differences in structure and life can be identified by comparing mushrooms with plants and animals?
5. Based on what features can we assume that all eukaryotes had common ancestors?

Kamensky A. A., Kriksunov E. V., Pasechnik V. V. Biology 10th grade
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