Genetics is a science that studies the laws of heredity and variability of all living beings. It is this science that gives us knowledge about the number of chromosomes in different types of organisms, the size of chromosomes, the location of genes on them, and how genes are inherited. Genetics also studies mutations that occur during the formation of new cells.
Chromosome set
Every living organism (the only exceptions are bacteria) has chromosomes. They are located in every cell of the body in a certain amount. In all somatic cells, chromosomes are repeated twice, thrice, or more times, depending on the type of animal or variety of plant organism. In germ cells, the chromosome set is haploid, that is, single. This is necessary so that when two germ cells merge, the correct set of genes for the body is restored. However, even in the haploid set of chromosomes, the genes responsible for the organization of the whole organism are concentrated. Some of them may not appear in the offspring if the second germ cell contains stronger traits.
How many chromosomes doescat?
You will find the answer to this question in this section. Each type of organism, plant or animal, contains a certain set of chromosomes. The chromosomes of one species of creatures have a certain length of the DNA molecule, a certain set of genes. Each such structure has its own size.
How many chromosomes do our pet cats and dogs have? A dog has 78 chromosomes. Knowing this number, is it possible to guess how many chromosomes a cat has? It's impossible to guess. Because there is no relationship between the number of chromosomes and the complexity of the organization of the animal. How many chromosomes does a cat have? Their 38.
Chromosome size differences
A DNA molecule, with the same number of genes located on it, can have different lengths in different species.
Moreover, the chromosomes themselves are of different sizes. One information structure can contain a long or very short DNA molecule. However, chromosomes are not too small. This is due to the fact that when the child structures diverge, a certain weight of the substance is necessary, otherwise the divergence itself will not occur.
The number of chromosomes in different animals
As mentioned above, there is no relationship between the number of chromosomes and the complexity of the organization of the animal, because these structures have a different size.
How many chromosomes a cat has, the same number of other cats: tiger, jaguar, leopard, puma and other members of this family. Many canids have 78 chromosomes. So much for domestic chicken. The domestic horse has 64, and the Przewalski horse has 76.
Uhuman 46 chromosomes. The gorilla and chimpanzee have 48, while the macaque has 42.
A frog has 26 chromosomes. In the somatic cell of a pigeon there are only 16 of them. And in a hedgehog - 96. In a cow - 120. In a lamprey - 174.
Next, we present data on the number of chromosomes in the cells of some invertebrates. The ant, like the roundworm, has only 2 chromosomes in each somatic cell. A bee has 16 of them. A butterfly has 380 such structures in a cell, and radiolarians have about 1600.
Animal data shows varying numbers of chromosomes. It must be added that Drosophila, which geneticists use in the course of genetic experiments, has 8 chromosomes in somatic cells.
The number of chromosomes in different plants
The plant world is also extremely diverse in terms of the number of these structures. So, peas and clover each have 14 chromosomes. Onion - 16. Birch - 84. Horsetail - 216, and fern - about 1200.
Differences between males and females
Males and females at the genetic level differ in only one chromosome. In females, this structure looks like the Russian letter "X", and in males it looks like "Y". In some animal species, females have a "Y" chromosome and males have an "X".
The traits found on such non-homologous chromosomes are inherited from father to son and from mother to daughter. The information that is fixed on the “Y” chromosome cannot be transferred to a girl, because a person who has this structure is necessarily male.
The same applies to animals: if we see a tricolor cat, we can definitelysay that we have a female in front of us.
Because only the X chromosome, which belongs to females, has the corresponding gene. This structure is the 19th in the haploid set, that is, in germ cells, where the number of chromosomes is always two times less than in somatic ones.
Work of breeders
Knowing the structure of the apparatus that stores information about the body, as well as the laws of inheritance of genes and the features of their manifestation, breeders breed new varieties of plants.
Wild wheat often has a diploid set of chromosomes. There are not many wild representatives that have a tetraploid set. Cultivated varieties often contain tetraploid and even hexaploid sets of structures in their somatic cells. This improves yield, weather resistance, and grain quality.
Genetics is an entertaining science. The device of the apparatus containing information about the structure of the whole organism is similar in all living beings. However, each type of creature has its own genetic characteristics. One of the characteristics of a species is the number of chromosomes. Organisms of the same species always have a certain constant amount of them.
