Do all living organisms have chromosomes? Do all mammalian cells have these structures? How many chromosomes does an organism have? Geneticists are engaged in the study of such issues. Many of these questions have already been answered. Data on the number, size and shape of chromosomes are increasingly used in other biological sciences. Particularly in taxonomy.
Chromosomes are information structures
What is a chromosome? If we consider a eukaryotic cell under high magnification, then in the normal state of this "brick" of the organism, we will not see any chromosome-like structures. They are formed only before cell division, and immediately after the end of reproduction, dense structures disappear, as if dissolving. Chromosomes are necessary for the uniform distribution of information material between daughter cells. They are formed by a DNA molecule and proteins that maintain the dense structure of the chromosome.
What is a karyotype
Each chromosome has its own size and shape. one vieworganisms are characterized by a certain set of chromosomes. Different individuals of the same species always have the same amount of these information structures, these structures have the size and shape characteristic of a particular species.
Thus, the karyotype is the external signs of chromosomes and their number in individuals of the same species. Unlike the genome, the karyotype does not include specific features of individuals, but only the appearance of chromosome structures. Karyotype features help taxonomists correctly distribute living organisms into taxonomic groups.
How many chromosomes do dogs have
Each species of organism has a certain number of chromosomes. This applies to all eukaryotes. Prokaryotes have a circular DNA molecule, which also doubles during cell division and is distributed among daughter cells without the formation of chromosome structures.
The number of chromosomes is extremely different in different representatives of the animal and plant kingdoms. For example, a person in somatic cells has 46 chromosomes. This is a diploid set. There are 23 structures in human germ cells. How many chromosomes do dogs have? Their number cannot be simply guessed for each organism. The dog karyotype consists of 78 chromosomes. How many chromosomes does a wolf have in this case? Here there is a similarity in karyotype. Because all wolves are relatives to each other and to the domestic dog. Almost all wolves also have 78 chromosomes in their somatic cells. The exceptions are the red wolf and the bush dog.
How many chromosomes do dogs have in germ cells? In germ cells, there are always two times fewer chromosomes than in somatic cells. Because they are distributed equally between daughter cells during meiosis.
The canine family includes, in addition to dogs and wolves, also foxes. The karyotype of a dog has 78 chromosomes. How many chromosomes do foxes have? The taxonomic genera of foxes are very heterogeneous in the number of chromosomes. The common fox has 38. The sand fox has 40. The Bengal fox has 60.
How many chromosomes are in a dog's red blood cells?
Erythrocytes are red blood cells that carry oxygen. How are they arranged? Mature red blood cells must contain a large amount of hemoglobin. That is why they do not have many organelles, including chromosomes, since there is no nucleus at all.
However, there are in the blood of dogs, as well as in human blood, reticulocytes - immature erythrocytes. They are only 1-2 percent of the total number of red blood cells. Reticulocytes contain ribosomal RNA, mitochondria, ribosomes, and the Golgi complex. But after a day or a day and a half, reticulocytes are transformed into mature erythrocytes that do not contain DNA, and, consequently, chromosomal structures.
How many chromosomes are in the karyotype of other animals
Animal species are very diverse in karyotype. Moreover, the number of chromosomes in the nuclei of cells of various animals does not depend on the complexity of the organization of a living being. So, for example, in the somatic cell of a frog, there are 26 chromosomes. Chimpanzees have 48, slightly more than humans. Domestic chicken has 78 structures. This is the same as the number of chromosomes in dogs. The carp has 104 of them, and the lamprey hasjawless vertebrate – 174.
Chromosome set of plants
The karyotype of plant forms is also extremely diverse. Soft wheat with a hexaploid set of chromosomes has 42 information structures, rye has 14, and corn has 20. Tomatoes have 24 chromosomes in each cell, the same number in rice. At Jerusalem artichoke - 102.
There are absolute champions in the plant kingdom in terms of the number of chromosomes. These are ferns.
There are about 1200 chromosomes in the cell of this ancient plant. Horsetail has many such structures: 216.
Thus, in all eukaryotic cells, except for erythrocytes, there are chromosomes. Depending on the type of animal or plant, the quantitative composition of chromosomes, as well as their size and shape, also change. It is precisely because the chromosomes are of different sizes that the number of these structures is so different. The smaller the structure, the more likely it is to have more.
