Chromosomes. Non-homologous and homologous chromosomes.

Chromosomes are the structural and functional elements of a human cell that contain genes. These units of the cell series are able to stain at the moment of cell division. Chromosomes have the form of rods, threads, loops, etc. By their length, these elements are heterogeneous. They consist of a centromere, a short and long arm, a secondary constriction, a satellite, a spindle thread, a limb. The location of such a part of the chromosome, as a centromere, affects the shape of the unit of the cell series itself. In the event that this part is located at the end of the structural-functional element, it will be rod-like. The finding of such a part as a centromere in the middle affects the fact that the chromosome takes the form of a hairpin equalizer. If the part under consideration is located to the side of the center, then the structural-functional element becomes a hairpin with different shoulders.

In general, there are 4 types of chromosome structure. The first type is the body-centric structural-functional elements. The second is acrocentric (the second shoulder is very short and almost invisible). The third type is submetacentric chromosomes, whose shape resembles the letter "L". Finally, the fourth species is metacentric. Chromosomes of this type have so-called shoulders, which are equal in length. In addition, these elements recall the letter and at the same time the symbol of victory "V".

It should be noted that each nucleus-containing human somatic cell contains twenty-three pairs of chromosomes, which are linear. In addition, there is a large number of copies of mitochondrial DNA (deoxyribonucleic acid).

It is worth saying a few words about the sex structural-functional elements of the human cell. These are Y and X chromosomes. The first contains approximately 58 pairs of nitrogenous bases, carries 78 genes and at the same time has a high mutation rate due to the environment in which it is located. This sex chromosome can only be transmitted through spermatozoa. They, in turn, are subject to a huge number of cell divisions occurring in the process of gametogenesis. The site of spermatozoa is a highly oxidative environment of the testicles, which stimulates the intensification of such a process as mutation. The second chromosome has approximately 150 million pairs of nitrogenous bases. It carries almost 1400 genes. Men have one X and one Y chromosome. Women have a different set. They have two X-chromosomes. One of them gets to the girl from the mother, and the second is inherited from the father's mother, i.e. From the grandmother along the line of the father.

Often there are questions about which chromosomes are called homologous and non-homologous. The answer is as follows. So, there are homologous chromosomes. These are paired structural-functional elements located in a diploid cell. Homologous chromosomes differ in that each of them was obtained from one and the other parent. Such elements have a similar nucleotide sequence along the entire length. This means that homologous chromosomes have the same genes, which are arranged in the same sequence. It is worth noting that the study of this topic is not only interesting, but also very useful in life, because it is better to know about your body as much as possible.

It should be added that homologous chromosomes constantly have the same type. For example, they can be integral, submetacentric, acrocentric, metacentric. Non-homologous chromosomes contain genes that are dissimilar. In addition, these structural and functional elements are not conjugated during meiosis. Non-homologous chromosomes, independently of one another, combine in a cell. This was proven during the study of the characteristics of inheritance characteristics. Also, this information was obtained using a direct cytological method.

The information listed above will help to have a basic understanding of chromosomes in general.