“Soma” means the body, that is, in theory, any cell in our body should be called somatic. However, reference books give a different definition. In fact, there are most somatic cells in the body, but there are other types of somatic cells in the body.
First of all, non-somatic are cells that later turn into an embryo. They share in a special way, uncharacteristic for somatic cells (meiosis), and have some other features. More recently, scientists have discovered a new class of cells that cannot be called either sexual or somatic. They are called stem cells, and any cell of the body can be made of them.
Somatic cells of vertebrates form bones, internal organs, skin, blood and connective tissues. And germ cells become sperm and ova. Unlike germ cells, somatic cells have a double set of special structures that ensure heredity - chromosomes.
All somatic cells carry a heritage from two organisms, one half of the chromosomes is almost identical to the chromosomes of the mother of our individual, and the second to the chromosomes of the father. We used the word “almost” because every organism undergoes mutation processes throughout life, that is, unplanned and unplanned changes in genes. Somatic cell mutations are not as serious as genital mutations. Because in the latter case, the whole new organism will bear the traces of changes (they are in the vast majority of cases undesirable for the body, useful mutations are very rare).
In general, somatic cells do not always have only two sets of chromosomes. Plants can have as many as four or six pairs of sets. The corresponding germ cells have 2-3 sets, which is understandable. For example, wheat can have four or six of them (depending on the species). In some cases, animal somatic cells also have more than two sets, for example, this is the case with salmon and salamander.
Sometimes too many sets of chromosomes (polyploidy) occur in humans, this may be a consequence of a violation of the mitosis process or the first phase of meiosis. In the first case, this is not scary - after all, only a few abnormal somatic cells are obtained, but if the germ cell becomes polyploid, then it is doomed, because during fertilization very serious violations of the whole organism are inevitable (if, nevertheless, the cell forms a zygote, the embryo dies) . Still, polyploidy is not normal for higher species.
Sometimes polyploidy, which is not normal in the norm for one or another species (usually plants), appears after the use of certain chemicals, which is an additional argument for tightening environmental control.
Somatic cell division creates cells identical to mother cells if the process occurred normally and there were no disturbances provoked by external and internal factors. The process of division of such cells is called mitosis and has long been studied by scientists. Such division is stable and reliable, but overall mitosis does not make any progress - the cells are obtained exactly like the cell that generated them. But genitals meet with the cells of another organism and form completely new cells that will become a unique organism and continue the evolutionary struggle.
Are there any ways to get the whole organism that would not differ genetically from the parent? Yes, this is called cloning. The technique is theoretically simple - take the somatic cell nucleus and plant it in the egg instead of the “native” nucleus. Such an egg does not need to be fertilized and can be planted in the uterus of a female individual. However, the technology is imperfect, in addition, the resulting organism turns out to be sick and can not live long. So it is not in vain that human cloning is prohibited.
Thus, somatic cells make up a large part of our body, share mitosis, and have two chromosome sets. This is the basic thing to know about this cell variety.