Cells, like the bricks of a house, are the building material of almost all living organisms. What parts do they consist of? What function in a cell is performed by various specialized structures? You will find answers to these and many other questions in our article.
What is a cell?
A cell is the smallest structural and functional unit of living organisms. Despite its relatively small size, it forms its own level of development. Examples of unicellular organisms are the green algae chlamydomonas and chlorella, the simplest animals euglena, amoeba and ciliates. Their sizes are really microscopic. However, the cell function of the body of this systematic unit is quite complex. These are nutrition, respiration, metabolism, spatial movement and reproduction.
General plan of cell structure
Not all living organisms have a cellular structure. For example, viruses are formed by nucleic acids and the protein coat. The cells are plants, animals, fungi and bacteria. All of them differ in structural features. However, their general structure is the same. It is represented by the surface apparatus, internal contents - cytoplasm, organelles and inclusions. Cell functions are determined by the structural features of these components. For example, in plants, photosynthesis is carried out on the inner surface of special organelles called chloroplasts. In animals, these structures are absent. The structure of the cell (the table "Structure and functions of organelles" considers in detail all the features) determines its role in nature. But for all multicellular organisms, the common thing is to ensure metabolism and the relationship between all organs.
Cell structure: table "Structure and functions of organelles"
This table will help to become familiar with the structure of cell structures.
| Cell structure | Structural features | Functions |
| Nucleus | Two-membrane organelle in the matrix of which are DNA molecules | Storage and transmission of hereditary information |
| Endoplasmic reticulum | System of cavities, tanks and tubules | Synthesis of Organic Substances |
| Golgi complex | Numerous pouch cavities | Storage and transportation of organic substances |
| Mitochondria | Round membranous organelles | Organic Oxidation |
| Plastids | Two-membered organelles, the inner surface of which forms outgrowths into the structure | Chloroplasts provide the process of photosynthesis, chromoplasts give color to various parts of plants, leukoplasts store starch |
| Ribosomes | Non-membrane organelles composed of large and small subunits | Protein biosynthesis |
| Vacuoli | In plant cells, these are cavities filled with cell sap, and in animals, contractile and digestive | Stock of water and minerals (plants). Contractile vacuoles remove excess water and salts, and digestive vacuoles - metabolism |
| Lysosomes | Rounded vesicles containing hydrolytic enzymes | Cleavage of biopolymers |
| Cell center | Non-membrane structure consisting of two centrioles | Formation of a spindle of division during cell crushing |
As you can see, each cell organelle has its own complex structure. Moreover, the structure of each of them determines the functions performed. Only the coordinated work of all organelles allows life to exist on the cellular, tissue and organism levels.
The main functions of the cell
The cell is a unique structure. On the one hand, each of its components plays a role. On the other hand, cell functions are subordinated to a single agreed mechanism of work. It is at this level of the organization of life that the most important processes are carried out. One of them is reproduction. It is based on the process of cell division. There are two main ways of it. So, gametes are divided by meiosis, all the rest (somatic) - mitosis.
Due to the fact that the membrane is semi-permeable, various substances can enter the cell and in the opposite direction. The basis for all metabolic processes is water. Entering the body, biopolymers are split into simple compounds. But minerals are in solutions in the form of ions.
Cell inclusions
Cell functions would not have been fully realized without inclusions. These substances are a reserve of organisms for an unfavorable period. It can be a drought, a drop in temperature, an insufficient amount of oxygen. The storing function of substances in the plant cell is performed by starch. It is in the cytoplasm in the form of granules. In animal cells, glycogen serves as a storage carbohydrate.
What are fabrics
In multicellular organisms, cells similar in structure and function are combined into tissues. This structure is specialized. For example, all cells of the epithelial tissue are small, tightly adjacent to each other. Their shape is very diverse. In this tissue, there is practically no intercellular substance. This structure resembles a shield. Due to this, the epithelial tissue performs a protective function. But any organism needs not only a "shield", but also a relationship with the environment. To carry out this function, in the epithelial tissue of animals there are special formations - pores. And in plants, the stomata of the skin or lentils of the cork serve as a similar structure. These structures carry out gas exchange, transpiration, photosynthesis, and thermoregulation. And above all, these processes are carried out at the molecular and cellular level.
The relationship of the structure and functions of cells
Cell functions are determined by their structure. All fabrics are a prime example of this. So, myofibrils are capable of contracting. These are muscle tissue cells that carry out the movement of individual parts and the entire body in space. But the connecting one has a different construction principle. This type of tissue consists of large cells. They are the basis of the whole organism. Connective tissue also contains a large amount of intercellular substance. Such a structure provides its sufficient volume. This type of tissue is represented by such varieties as blood, cartilage, bone tissue.
They say that nerve cells do not recover ... There are many different views on this fact. However, no one doubts that neurons bind the whole organism into a single whole. This is achieved by another structural feature. Neurons consist of a body and processes - axons and dendrites. According to them, information comes sequentially from nerve endings to the brain, and from there - back to the working organs. As a result of the work of neurons, the whole organism is connected by a single network.
So, most living organisms have a cellular structure. These structures are structural units of plants, animals, fungi and bacteria. Common functions of cells are the ability to divide, perception of environmental factors and metabolism.