The cell - the smallest structure of the whole plant and animal world - is the most mysterious phenomenon of nature. Even at its own level, the cell is extremely complex and contains many structures that perform certain functions. In the body, the totality of certain cells forms tissues, tissues form organs, and those form organ systems. The structure of the animal and plant cells is largely similar, but at the same time, it has fundamental differences. For example, the chemical composition of the cells is similar, the principles of structure and life are similar, but plant cells do not have centrioles (except algae), and starch serves as a nutritional reserve base.
The structure of the animal’s cell is based on three main components - the nucleus, cytoplasm and cell membrane. Together with the nucleus, the cytoplasm forms a protoplasm. The cell membrane is a biological membrane (septum) that separates the cell from the external environment, serves as a membrane for cellular organelles and nuclei, and forms cytoplasmic compartments. If you place the drug under a microscope, then the structure of the animal cell can be easily seen. The cell membrane contains three layers. The outer and inner layers are protein, and the intermediate is lipid. In this case, the lipid layer is divided into two layers - a layer of hydrophobic molecules and a layer of hydrophilic molecules, which are arranged in a certain order. On the surface of the cell membrane is a special structure - glycocalyx, which provides the selective ability of the membrane. The shell passes the necessary substances and delays those that cause harm. The structure of the animal cell is aimed at providing protective functions already at this level. The penetration of substances through the membrane occurs with the direct participation of the cytoplasmic membrane. The surface of this membrane is quite significant due to bends, outgrowths, folds and villi. The cytoplasmic membrane passes both the smallest particles and larger ones.
The structure of an animal cell is characterized by the presence of a cytoplasm, most of which consists of water. The cytoplasm is a receptacle for organoids and inclusions. In addition, the cytoplasm also contains the cytoskeleton - protein filaments that participate in the process of cell division, delimit the intracellular space and maintain the cellular form, the ability to contract. An important component of the cytoplasm is hyaloplasma, which determines the viscosity and elasticity of the cell structure. Depending on the external and internal factors, the hyaloplasm can change its viscosity - become liquid or gel-like.
Studying the structure of an animal cell, one cannot but pay attention to the cellular apparatus - the organelles that are in the cell. All organelles have their own specific structure, which is due to the functions performed. The nucleus is the central cell unit that contains hereditary information and is involved in the metabolism of the cell itself. Cell organelles include the endoplasmic reticulum, cell center, mitochondria, ribosomes, Golgi complex, plastids, lysosomes, vacuoles. There are similar organelles in any cell, but, depending on the function, the structure of the animal cell may differ in the presence of specific structures.
Functions of cell organelles:
- mitochondria oxidize organic compounds and accumulate chemical energy;
- the endoplasmic reticulum, due to the presence of special enzymes, synthesizes fats and carbohydrates, its channels facilitate the transport of substances within the cell;
- ribosomes synthesize protein;
- The Golgi complex concentrates the protein, compacts the synthesized fats, polysaccharides, forms lysosomes and prepares substances for their removal from the cell or direct use inside it;
- lysosomes break down carbohydrates, proteins, nucleic acids and fats, in fact, digesting nutrients entering the cell;
- the cell center is involved in the process of cell division;
- vacuoles, due to the content of cellular juice, support cell turgor (internal pressure).
The structure of a living cell is extremely complex - at the cellular level there are many biochemical processes that, together, provide the vital activity of the body.