A human cell does not differ from a similar structure in the body of other animals, if we consider only the general plan of the structure. Analyzing the structure of a human cell , cytologists distinguish two areas that differ in functions - the nucleus and cytoplasm. Cytoplasm performs daily activities, providing the constant needs of a unit of all living things.
All specific functions, such as contractions of a muscle cell or transmission of a nerve signal, are also performed due to the work of the cytoplasm. Therefore, in different types of cells, the cytoplasm is different. But the core in structure is the same even in different species.
The structure of the cell nucleus is quite uniform in living units of various types. There are blocks of chromatin and nucleoli. Chromatin is not a chemical compound at all, it is just DNA in a “packed" state. In chromatin, there is also RNA and some histone proteins.
The core is most often round or oval. But there are elongated, and separated by transverse constrictions (this happens in neutrophils). Considering the structure of a human cell, it should be noted that a whole system of membranes exists in it and the interphase (outside fission) nucleus is always surrounded by a nuclear membrane. There are holes in the shell called nuclear pores. Through them, macromolecules pass into and out of the nucleus.
The internal environment of the nucleus is very different from the environment of the cell, this is ensured by thin diaphragms of the pores, which allow only the substances necessary for the nucleus to pass inside. So the nucleus exchanges chemical information with the cytoplasm. In the nucleolus, rRNA is formed, which is necessary for cell reproduction. Often the nucleoli merge into one, and one large nucleolus is visible in the microscope.
By its chemical composition, nuclear juice is a colloidal solution of proteins; it does not stain well on preparations for an electron microscope and looks like a bright area in microphotographs. This is a rather rarefied environment where the diffusion of metabolites is facilitated, and genetic material can move extremely quickly.
But what does the cytoplasm do? Her “duties" do not include only the organization of reproduction, she can do the rest. The structure of a human cell is such that the basis of life - oxidation, occurs precisely in the cytoplasm. It consists of many small structures called organelles or organoids, by analogy with organs in a large organism.
Most organelles are membrane structures. Only free ribosomes, centrioles, cilia and flagella do not contain membranes (all three types of organelles consist of microtubules), as well as fibrillar structures (microfilaments and fibrils).
The structure of a human cell is in principle membrane, that is, all departments are closed by membranes. Mitochondria, for example, generally have two layers of membranes in which the synthesis of energy molecules occurs - ATP as a result of cellular respiration reactions . Mitochondria are unique because they are parasites that become symbionts. They have their own genome and are generally quite independent. They are thought to be from bacteria.
Ribosomes, which sometimes combine into polyribosomes, are involved in the synthesis of the protein necessary for the cytoplasm. And it is very necessary not only for building structures, but also in order to keep the balance of osmotic pressure normal.
The endoplasmic reticulum is a vesicle connected together. Some of them have ribosomes. The protein that they synthesize does not float in the cytoplasm juice - the cytosol, but is isolated before being removed from the cell or when used for other purposes.
The Golgi apparatus is something like a stack of pouches. Various substances are accumulated and sorted in it. Proteins here acquire their final structure, and it is also here that lysosomes form.
Speaking of lysosomes. They destroy the unnecessary components of the cells, if something is wrong with them, then diseases of accumulation develop. After the death of the cell, they even destroy the environment of the dead dead unit of the living, and not just itself.
The structure of a living cell differs from the structure of a dead one primarily in that karyolysis occurs in the deceased - nucleus decay and digestion of the cell contents after resorption of the lysosome membranes.