What does a living cell look like? Similarities between plant and animal cells. What are the cells

Cells of different kingdoms have many common features, but there are also significant differences.

We will consider the cells of 4 living organisms - animals, plants, fungi and bacteria.

Let us describe their common organelles and what distinguishes them.

bacterial cell

It differs from all the others as the most simply arranged.

Cell wall- 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

Ribosomes- synthesize protein.
mesosomes- implementation of redox processes.
There is no nucleus nucleoid- circular DNA and RNA.
flagella- provide movement.

plant cell

cell wall- the functions are the same, a reserve nutrient - carbohydrate - starch, cellulose, etc.
Membrane- protection and metabolism, a slight difference - yes plasmodesmata- something like bridges between neighboring cells in multicellular plants.
Cytoplasm- internal semi-liquid medium, contains nutrients.
Ribosomes- there is, but a little, they synthesize protein.
Nucleus- the genetic information center of the cell.
EPS(endoplasmic reticulum), smooth (without ribosomes) - provides transport of substances, maintains the shape of the cell, rough - ribosomes on it provide protein synthesis.
Cytoplasm- internal semi-liquid medium, contains nutrients.
Chloroplast- obligatory organoid exclusively plant cell. The function is photosynthesis.
Vacuole- also a plant organoid - a supply of cell sap.
Mitochondria- ATP synthesis - providing cells with energy.
Lysosomes- digestive organelles.
golgi apparatus- Produces lysosomes and stores nutrients.
Microfilaments- protein filaments - "rails" for the movement of some organelles, are involved in cell division.
microtubules- about the same as microfilaments, only thicker.

animal cage

There is no cell wall, no chloroplasts, no vacuoles.

The rest of the organelles are the same as in the plant cell, there is one “addendum” - a component of ONLY the animal cell - centrioles- participate in cell division, being responsible for the correct divergence of chromosomes.

mushroom cell

Drawings of an animal cell are never found in the Unified State Examination, and the structure of the cell is considered only in comparison with the animal and plant.

In structure, it is very similar to an animal, only there are no centrioles and there is a cell wall, the reserve nutrient of which is glycogen.

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Almost all living organisms are based on the simplest unit - the cell. You can find a photo of this tiny biosystem, as well as answers to the most interesting questions in this article. What is the structure and size of the cell? What functions does it perform in the body?

The cage is...

Scientists don't know certain time the emergence of the first living cells on our planet. In Australia, their remains were found 3.5 billion years old. However, it was not possible to accurately determine their biogenicity.

The cell is the simplest unit in the structure of almost all living organisms. The only exceptions are viruses and viroids, which are non-cellular life forms.

A cell is a structure that can exist autonomously and reproduce itself. Its dimensions can be different - from 0.1 to 100 microns or more. However, it is worth noting that unfertilized feathered eggs can also be considered cells. Thus, the largest cell on Earth can be considered an ostrich egg. In diameter, it can reach 15 centimeters.

The science that studies the characteristics of life and the structure of the cell of the body is called cytology (or cell biology).

Discovery and exploration of the cell

Robert Hooke is an English scientist who is known to all of us from a school physics course (it was he who discovered the law on the deformation of elastic bodies, which was named after him). In addition, it was he who first saw living cells, examining sections of a cork tree through his microscope. They reminded him of a honeycomb, so he called them cell, which means "cell" in English.

The cellular structure of plants was confirmed later (at the end of the 17th century) by many researchers. But the cell theory was extended to animal organisms only in early XIX century. Around the same time, scientists became seriously interested in the contents (structure) of cells.

A detailed examination of the cell and its structure was made possible by powerful light microscopes. They still remain the main tool in the study of these systems. And the appearance in the last century electron microscopes enabled biologists to study the ultrastructure of cells. Among the methods of their study, one can also single out biochemical, analytical and preparative ones. You can also see what it looks like living cell, - the photo is given in the article.

Chemical structure of the cell

The cell contains many different substances:

• organogens;
• macronutrients;
• micro- and ultramicroelements;
• water.

About 98% chemical composition cells make up the so-called organogens (carbon, oxygen, hydrogen and nitrogen), another 2% are macronutrients (magnesium, iron, calcium and others). Micro- and ultramicroelements (zinc, manganese, uranium, iodine, etc.) - no more than 0.01% of the whole cell.

Prokaryotes and eukaryotes: the main differences

Based on the characteristics of the cell structure, all living organisms on Earth are divided into two kingdoms:

• prokaryotes are more primitive organisms that have evolved;
• eukaryotes - organisms whose cell nucleus is fully formed (the human body also belongs to eukaryotes).

The main differences between eukaryotic cells and prokaryotes:

• larger sizes (10-100 microns);
• method of division (meiosis or mitosis);
• ribosome type (80S-ribosomes);
• type of flagella (in the cells of eukaryotic organisms, flagella consist of microtubules that are surrounded by a membrane).

eukaryotic cell structure

The structure of a eukaryotic cell includes the following organelles:

• nucleus;
• cytoplasm;
• golgi apparatus;
• lysosomes;
• centrioles;
• mitochondria;
• ribosomes;
• vesicles.

The core is the main structural element eukaryotic cells. It is in it that all the genetic information about a particular organism is stored (in DNA molecules).

Cytoplasm is a special substance that contains the nucleus and all other organelles. Thanks to a special network of microtubules, it ensures the movement of substances within the cell.

The Golgi apparatus is a system of flat tanks in which proteins constantly mature.

Lysosomes are small bodies with a single membrane, the main function of which is to break down individual cell organelles.

Ribosomes are universal ultramicroscopic organelles, the purpose of which is the synthesis of proteins.

Mitochondria are a kind of "light" cells, as well as its main source of energy.

Basic functions of the cell

The cell of a living organism is designed to perform several important functions that ensure the vital activity of this very organism.

The most important function of the cell is metabolism. Yes, it is she who splits complex substances, turning them into simple ones, and also synthesizes more complex compounds.

In addition, all cells are able to respond to external influences. annoying factors(temperature, light, etc.). Most of them also have the ability to regenerate (self-heal) through fission.

Nerve cells can also respond to external stimuli through the formation of bioelectric impulses.

All of the above functions of the cell ensure the vital activity of the organism.

Conclusion

So, a cell is the smallest elementary living system, which is the basic unit in the structure of any organism (animal, plant, bacteria). In its structure, the nucleus and cytoplasm are distinguished, which contains all the organelles (cellular structures). Each of them performs its specific functions.

Cell size varies widely - from 0.1 to 100 micrometers. Features of the structure and vital activity of cells are studied by a special science - cytology.

The biology of the cell in general terms known to each school curriculum. We invite you to remember what you once studied, as well as discover something new about it. The name "cell" was proposed as early as 1665 by the Englishman R. Hooke. However, it was only in the 19th century that it began to be studied systematically. Scientists were interested, among other things, in the role of the cell in the body. They can be part of many different organs and organisms (eggs, bacteria, nerves, erythrocytes) or be independent organisms (protozoa). Despite all their diversity, there is much in common in their functions and structure.

Cell functions

All of them are different in form and often in function. Cells of tissues and organs of one organism can also differ quite strongly. However, the biology of the cell highlights the functions that are inherent in all their varieties. This is where protein synthesis always takes place. This process is controlled. A cell that does not synthesize proteins is essentially dead. A living cell is one whose components change all the time. However, the main classes of substances remain unchanged.

All processes in the cell are carried out using energy. These are nutrition, respiration, reproduction, metabolism. Therefore, a living cell is characterized by the fact that energy exchange takes place in it all the time. Each of them has a common the most important property- the ability to store energy and spend it. Other functions include division and irritability.

All living cells can react to chemical or physical changes the environment surrounding them. This property is called excitability or irritability. In cells, when excited, the rate of decay of substances and biosynthesis, temperature, and oxygen consumption change. In this state, they perform the functions peculiar to them.

Cell structure

Its structure is quite complex, although it is considered the simplest form of life in such a science as biology. Cells are located in intercellular substance. It provides them with breathing, nutrition and mechanical strength. The nucleus and cytoplasm are the main components of every cell. Each of them is covered with a membrane, the building element for which is a molecule. Biology has established that the membrane is made up of many molecules. They are arranged in several layers. Thanks to the membrane, substances penetrate selectively. In the cytoplasm are organelles - the smallest structures. These are the endoplasmic reticulum, mitochondria, ribosomes, cell center, Golgi complex, lysosomes. You will better understand what cells look like by studying the drawings presented in this article.

Membrane

Endoplasmic reticulum

This organoid was named so because it is located in the central part of the cytoplasm (from the Greek the word "endon" is translated as "inside"). EPS is a very branched system of vesicles, tubules, tubules of various shapes and sizes. They are separated from membranes.

There are two types of EPS. The first is granular, which consists of tanks and tubules, the surface of which is dotted with granules (grains). The second type of EPS is agranular, that is, smooth. Grans are ribosomes. Curiously, granular EPS is mainly observed in the cells of animal embryos, while in adult forms it is usually agranular. Ribosomes are known to be the site of protein synthesis in the cytoplasm. Based on this, it can be assumed that granular EPS occurs mainly in cells where active protein synthesis occurs. The agranular network is believed to be represented mainly in those cells where active lipid synthesis occurs, that is, fats and various fat-like substances.

Both types of EPS not only take part in the synthesis of organic substances. Here these substances accumulate and are also transported to the necessary places. EPS also regulates the metabolism that occurs between environment and a cell.

Ribosomes

Mitochondria

Energy organelles include mitochondria (pictured above) and chloroplasts. Mitochondria are the original powerhouses of every cell. It is in them that energy is extracted from nutrients. Mitochondria have a variable shape, but most often they are granules or filaments. Their number and size are not constant. It depends on what functional activity one cell or another.

If we consider an electron micrograph, we can see that mitochondria have two membranes: inner and outer. The inner one forms outgrowths (cristae) covered with enzymes. Due to the presence of cristae, the total surface of mitochondria increases. This is important for the activity of enzymes to proceed actively.

In mitochondria, scientists have found specific ribosomes and DNA. This allows these organelles to reproduce on their own during cell division.

Chloroplasts

As for chloroplasts, in shape it is a disk or a ball with a double shell (inner and outer). Inside this organoid there are also ribosomes, DNA and grana - special membrane formations associated both with the inner membrane and with each other. Chlorophyll is found in the membranes of the gran. Thanks to him, the energy sunlight converts adenosine triphosphate (ATP) into chemical energy. In chloroplasts, it is used for the synthesis of carbohydrates (formed from water and carbon dioxide).

Agree, you need to know the information presented above not only in order to pass a biology test. The cell is the building material that makes up our body. Yes and all Live nature is a complex collection of cells. As you can see, there are many constituent parts. At first glance, it may seem that to study the structure of the cell - not an easy task. However, if you look, this topic is not so complicated. It is necessary to know it in order to be well versed in a science such as biology. The composition of the cell is one of its fundamental themes.

The cell (cellula) is a living system consisting of two parts - the cytoplasm and the nucleus, which are the basis of the structure, development and life of all animals and plant organisms(Fig. 5, 6). Cells combined with extracellular structures form tissues. The control and relationship of cells that are part of tissues is established nervous system and hormones. Adhesion (adhesion) of cells ensures the structural and functional unity of tissues. The development of cell structure in phylogenesis had great importance in the evolution of organic life. Thanks to cell structure reproduction, growth and transfer of hereditary properties to new organisms, restoration of organs and tissues (regeneration) are possible. The cells of each tissue have different shape: plates, cubes, cylinders, balls, spindles or even pass without clear boundaries into each other (syncytium). These forms are often depicted from cells that are densified (fixed) chemicals. In fact, living cells have uneven contours with numerous protrusions and processes, which are very dynamic formations.

5. Scheme of the submicroscopic structure of a fixed cell. 1 - cell membrane; 2 - hyaloplasm; 3 - intracellular threads; 4 - lipoid granules; 5 - ergastoplasm and in it: 6 - alpha cytomembranes; 7- ribosomes; 8 - cores; 9 - pores in the nuclear envelope; 10 - nuclear envelope; 11 - nucleolus; 12 - intracellular mesh apparatus; 13 - mitochondria; 14 centrioles.

6. Scheme of the structure of a fixed cell under light microscopy. 1 - cell membrane; 2 - cytoplasm; 3 - intracellular mesh apparatus; 4 - cell center; 5 - mitochondria; 6 - protein granules; 7 - core with shell; 8 - lumps of chromatin; 9 - nucleolus; 10 - vacuoles; 11 - lipoid granules.

The cell consists of a nucleus and cytoplasm. The nucleus (nucleus) has a spherical ovoid shape and contains chromosomes that are well expressed in the phase of cell division and are not visible in the interphase nuclei. The nucleus consists of: a) chromatin, which has the form of lumps or threads. Nuclear deoxyribonucleic acid (DNA) is localized in chromatin and is associated only with chromosomes, which during mitotic division are helically twisted into chromonemes. During the interphase period, the chromosomes straighten out and their thinnest threads are visible only with electron microscopy; b) karyolymph (nuclear juice) - an environment where swollen despiralized chromosomes, nucleoli and globulins are localized; c) nucleoli that synthesize ribonucleic acid (RNA), which penetrates into the cytoplasm through the pores of the nuclear envelope. They consist of ribonucleoprotein and RNA granules. The nucleoli disappear during nuclear division. In cells that actively synthesize protein, there are large nucleoli with great content RNA; d) the nuclear envelope, consisting of two membranes pierced through holes through which the karyolymph communicates with the cytoplasm.

For the most part, there is one nucleus in the cells, except for mature erythrocytes, where the nucleus is absent; there are cells with two, three and hundreds of nuclei. The function of the nucleus is more active between cell divisions. Chemical structure the nucleus consists of DNA, RNA, salts of Mg, Na, K, Ca, precursors of nucleic acids-nucleotides and nuclear proteins: a) histones associated with DNA; b) globulins connected with nuclear enzymes of nucleic metabolism and anaerobic glycolysis; c) non-histone proteins associated with RNA; d) insoluble proteins.

The cytoplasm is the basis where various organelles and inclusions are located in the main substance of the cell, which is a structureless globular hyaloplasm.

Organelles. Microtubules are three-layer formations that serve as supporting elements for other organelles and cell inclusions. Ribosomes are particles of protein, RNA, Mg salts and polyamines in the form of granules, free and attached to the membrane of the ergastoplasmic reticulum. Ribosomes synthesize proteins. Ergastoplasmic (endoplasmic) reticulum consists of vacuolated elements various forms. Ribosome granules are attached to the outer membrane of this network. The network is extremely dynamic, easily rebuilt with external influences into spherical, saccular, lamellar formations. The ergastoplasmic reticulum is involved in the synthesis of proteins and in the conduction of excitation inside the cell. The Golgi complex has a network structure, located near the nucleus and surrounding the cell center. Represents flattened sacs or cisterns containing secretion products of the ergastoplasmic complex. Lysosomes are spherical particles containing about 12 hydrolytic enzymes. Mitochondria have the form of filamentous formations consisting of two-layer membranes. In the center of the mitochondria are cristae (ridges), which are derivatives of the inner layer. Mitochondria are involved in the oxidation of substances. The cell center is located near the nucleus and has the form of cylindrical tubes called centrioles. During mitotic cell division, centrioles orient chromosomes along the poles of the cell. Specialized structures of the cytoplasm are microvilli, cilia, flagella, myofibrils, neurofibrils, tonofibrils.

Inclusions. In the process of metabolism in the cell are deposited various substances type of protein, lipid, carbohydrate, pigment granules.

Cancer cells develop from healthy parts of the body. They do not penetrate tissues and organs from the outside, but are part of them.

Under the influence of factors that have not been fully studied, malignant formations stop responding to signals and begin to behave differently. Changes and appearance cells.

malignant tumor is formed from a single cell that has become cancerous. This happens because of the modifications that occur in the genes. Most malignant particles have 60 or more mutations.

Before the final transformation into a cancer cell, it goes through a series of transformations. As a result, some of the pathological cells die, but a few survive and become oncological.

When a normal cell mutates, it goes into the stage of hyperplasia, then atypical hyperplasia, turns into carcinoma. Over time, it becomes invasive, that is, it moves through the body.

What is a healthy particle

It is generally accepted that cells are the first step in the organization of all living organisms. They are responsible for ensuring all vital functions e.g. growth, metabolism, transmission of biological information. In the literature, they are called somatic, that is, those that make up the entire human body, except for those that take part in sexual reproduction.

The particles that make up a person are very diverse. However, they have a number common features. All healthy elements go through the same stages of their development. life path. It all starts at birth, then there is a process of maturation and functioning. It ends with the death of the particle as a result of the triggering of the genetic mechanism.

The process of self-destruction is called apoptosis, it occurs without disturbing the viability of surrounding tissues and inflammatory reactions.

For your life cycle healthy particles divide a certain number of times, that is, they begin to reproduce only if there is a need. This happens after receiving a signal to divide. There is no division limit in sex and stem cells, lymphocytes.

Five interesting facts

Malignant particles are formed from healthy tissues. In the process of their development, they begin to differ significantly from ordinary cells.

Scientists managed to identify the main features of oncoforming particles:

• Infinitely divided- the pathological cell doubles and increases in size all the time. Over time, this leads to the formation of a tumor, consisting of a huge number of copies of the oncological particle.
• Cells separate from each other and exist autonomously- they lose the molecular bond between themselves and cease to stick together. This leads to the movement of malignant elements throughout the body and their deposition on various organs.
• Cannot manage its life cycle- The p53 protein is responsible for cell repair. In most cancer cells, this protein is defective, so the life cycle is not well managed. Experts call such a defect immortality.
• Lack of development- malignant elements lose their signal with the body and are engaged in endless division, not having time to mature. Because of this, they form multiple gene errors that affect their functional abilities.
• Each cell has different external parameters- pathological elements are formed from various healthy parts of the body, which have their own characteristics in appearance. Therefore, they differ in size and shape.

There are malignant elements that do not form a lump, but accumulate in the blood. An example is leukemia. When dividing, cancer cells get more and more errors.. This leads to the fact that subsequent elements of the tumor may be completely different from the initial pathological particle.

Many experts believe that oncological particles begin to move inside the body immediately after the formation of a neoplasm. To do this, they use blood and lymphatic vessels. Most of them die as a result of work immune system, but units survive and settle on healthy tissues.

All detailed information about cancer cells in this scientific lecture:

The structure of the malignant particle

Violations in the genes lead not only to changes in the functioning of cells, but also to the disorganization of their structure. They change in size internal structure, the form of a complete set of chromosomes. These visible violations allow specialists to distinguish them from healthy particles. Examining cells under a microscope can diagnose cancer.

Nucleus

There are tens of thousands of genes in the nucleus. They direct the functioning of the cell, dictating its behavior to it. Most often, the nuclei are located in the central part, but in some cases they can be displaced to one side of the membrane.

In cancer cells, the nuclei differ most of all, they become larger, acquire a spongy structure. The nuclei have depressed segments, indented membrane, enlarged and distorted nucleoli.

Proteins

Protein Challenge in performing the basic functions that are necessary to maintain the viability of the cell. They transport nutrients to it, convert them into energy, transmit information about changes in the external environment. Some proteins are enzymes whose task is to convert unused substances into necessary products.

In a cancer cell, proteins are modified, they lose the ability to do their job correctly. Errors affect enzymes and the life cycle of the particle is changed.

Mitochondria

The part of the cell in which products such as proteins, sugars, lipids are converted into energy is called the mitochondria. This conversion uses oxygen. As a result, toxic wastes such as free radicals. It is believed that they can start the process of turning a cell into a cancer cell.

plasma membrane

All elements of the particle are surrounded by a wall made of lipids and proteins. The task of the membrane is to keep all of them in their places. In addition, it blocks the way to those substances that should not enter the cell from the body.

Special proteins of the membrane, which are its receptors, perform important function. They transmit coded messages to the cell, according to which it reacts to changes in the environment..

Misreading the genes leads to changes in the production of receptors. Because of this, the particle does not learn about changes in the external environment and begins to lead an autonomous way of existence. This behavior leads to cancer.

Malignant particles of various organs

Cancer cells can be recognized by their shape. Not only do they behave differently, but they also look different than normal.

Scientists from Clarkson University conducted research, as a result of which they came to the conclusion that healthy and pathological particles differ in geometric outlines. For example, malignant cells cervical cancers have a higher degree of fractality.

Fractal are called geometric figures, which are made up of similar parts. Each of them looks like a copy of the whole figure.

Scientists were able to obtain an image of cancer cells using an atomic force microscope. The device made it possible to obtain a three-dimensional map of the surface of the particle under study.

Scientists continue to study the changes in fractality during the process of transforming normal particles into oncological ones.

Lungs' cancer

Lung pathology is non-small cell and small cell. In the first case, tumor particles divide slowly into late stages they pinch off from the maternal focus and move through the body due to the flow of lymph.

In the second case, the neoplasm particles are small in size and tend to rapidly divide. In a month, the number of cancer particles doubles. Elements of the tumor are able to spread both to the organs and to the bone tissues.

The cell has an irregular shape with rounded areas. On the surface, multiple growths of different structures are visible. The color of the cell is beige at the edges, and becomes red towards the middle.

breast cancer

Oncoformation in the breast may consist of particles that have been transformed from components such as connective and glandular tissue, ducts. The elements of the tumor themselves can be large and small. With highly differentiated pathology of the breast, the particles differ in nuclei of the same size.

The cell has round shape, its surface is loose, inhomogeneous. Long straight processes protrude from it in all directions. Edge color cancer cell lighter and brighter, and darker and richer inside.

Skin cancer

Skin cancer is most often associated with transformation into malignant form melanocytes. Cells are located in the skin in any part of the body. Experts often associate these pathological changes with prolonged exposure to the open sun or in the solarium. Ultraviolet radiation contributes to the mutation of healthy elements of the skin.

Cancer cells for a long time develop on the surface skin. In some cases, pathological particles behave more aggressively, quickly growing deep into the skin.

Cancer cell has a rounded shape, over the entire surface of which multiple villi are visible. Their color is lighter than that of the membrane.

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