Cells of all living organisms have a similar structure. All of them consist of a plasma membrane, a membrane around it (a glycocalyx in animals or a cell wall: in fungi - from chitin, in plants - from cellulose), cytoplasm (organelles are located in it, each of which performs its functions, a cell center, for example, takes part in division) and the nucleus, which protects DNA (except for prokaryotes).
Cell organelles
These include ribosomes, lysosomes, mitochondria, the Golgi complex, the endoplasmic reticulum and the cell center. Plant cells also contain specific organelles that are unique to them - vacuoles. They accumulate unnecessary substances, plastids (chromoplasts, leukoplasts, chloroplasts, in the latter the process of photosynthesis takes place). The functions of the cell center, mitochondria, ribosomes and other structures are very important. Mitochondria act as a kind of energy production stations, they are the process of intracellular respiration. Ribosomes are responsible for the production of proteins, synthesizing them from individual amino acids in the presence of mRNA, which contains information about the substances needed by the cell. The function of lysosomes is to break down chemicalcompounds with the help of enzymes that are contained inside the organoid. The Golgi complex accumulates and stores certain substances. The endoplasmic reticulum is also involved in metabolism.
Cell center - structure and functions
This organelle is also called the centrosome. It is difficult to overestimate the functions of the cell center - without this organoid, cell division would be impossible. It consists of two parts. In this, the cell center is similar to the ribosome, in the structure of which there are also two halves. Parts of the centrosome are called centrioles, each of them looks like a hollow cylinder formed from microtubules. They are located perpendicular to each other. The functions of the cell center are the formation of the division spindle by centrioles during meiosis or mitosis.
How does a cell divide?
There are two main ways - meiosis and mitosis. The functions of the cell center are manifested in both processes. In both the first and second cases, the division occurs in several stages. There are such stages: prophase, metaphase, anaphase, telophase.
Meiosis usually involves two consecutive cell divisions, the time between them is called interphase. As a result of this process, from a cell with a diploid set of chromosomes (double), several with a haploid (single) are formed. In the process of mitosis, the number of chromosomes does not decrease - daughter cells also have a diploid set. There is also such a method of division as amitosis. In thiscase, the nucleus, and then the entire cytoplasm, is simply divided in two. This species is far from being as common as the first two, it is found mainly among protozoa. The cell center is not involved in this process.
Participation of the cell center in division
Prophase implies preparation for the process of mitosis or meiosis, during which the nuclear membranes are destroyed. During metaphase, the cell center separates into two separate centrioles. They, in turn, diverge to opposite poles of the cell. At the same stage, the chromosomes line up along the equator. They are then attached to the centrioles by spindle threads in such a way that different chromatids of each chromosome are attached to opposite centrioles. During metaphase, each of the chromosomes splits into separate chromatids, which are attracted to opposite poles by centrioles by threads.
During telophase, the formation of nuclear membranes occurs, the cytoplasm separates and daughter cells are finally formed.
