Cats are the pets of many people. Someone likes red, someone black, someone mosaic. Others are attracted to Persians, Siamese cats or Egyptian cats. It's all a matter of taste.
However, the color of the animal, its exterior, character, diseases, pathologies, mutations depend not only on the breed or lifestyle, but also on the chromosome set (primarily on it), which is constant and certain.
And yet, how many chromosomes does a cat have, what is their number and function? This will be discussed below.
Genome and chromosomes
Talking about how many chromosomes a cat has is extremely difficult without basic knowledge of genetics.
Genome is a structure that contains genetic information about an organism. Almost every cell contains a genome. But the chromosome contains all the information about the structure of the cell. The chromosome is a nucleoprotein structure in the nucleus of a eukaryotic cell. The chromosome contains a significant part of the hereditary information that is stored,implemented and passed on to future generations.
Chromosome is the structure of the cell nucleus, consisting of deoxyribonucleic acid (DNA) and proteins. It is worth recalling that DNA is a macromolecule that provides storage, transmission from generation to generation, implementation of the genetic program for the development of a living organism.
There are two types of chromosomes in different organisms:
Eukaryotic type - characteristic of living organisms (eukaryotes), whose cells contain a nuclear envelope, DNA molecules in the nucleus and mitochondria.
Prokaryotic type - found in organisms whose cells lack a nuclear membrane, and DNA molecules are enclosed in histones (prokaryotes).
Externally, a chromosome looks like a long thread with strung beads, each of which is a gene. In addition, the gene is located on its strictly fixed section of the chromosome - the locus.
The number of chromosomes in animals
How many chromosomes are in a cat's cells? Any living organism has homologous or paired chromosomes and haploid or unpaired (sex) chromosomes. The latter include the egg and sperm, they have a set of XX and XY, respectively. When dividing, they break up into X, X and X, Y. Depending on the new combination of the pair in the fertilized cell, the sex of the new organism (in our case, a kitten) will be determined.
To the question: "How many chromosomes are in a cat's cells?", genetics gives the exact answer. In a domestic cat, the chromosome set includes 19 pairs of chromosomes (18 paired and 1 unpaired: XX - in females and XY -in males). The total number of chromosomes in a cat is 38.
In other animals, the number of chromosomes is unchanged and individual for each species (for example, in dogs - 78 chromosomes, in horses - 64, in cows - 60, in a hare - 48). Recall that humans have 46 chromosomes.
Karyotype and chromosomal complex of the cat
Karyotype is a paired set of chromosomes with a specific number, size and shape for each animal species. The signs of each type of living organism are inherited according to the karyotype. For example, the presence of a trunk in elephants can be a karyotypic feature. The birth of a baby elephant without a trunk will be a deviation from the karyotypic norm, that is, a pathology.
All cells are paired, the future appearance, exterior, color, character of the cat depends on them. The last - 19th pair contains sexual information and half of the chromosome set. During fertilization, both parts are combined to form a complete cell.
Cat's egg chromosomes
What set of chromosomes does a cat's egg have? There are 38 chromosomes in the somatic cell of a cat, which are diploid cells. The ovum is a sex haploid cell. Accordingly, 38 must be divided by two, we get 19, that is, there are nineteen chromosomes in a cat's egg.
Heredity of cats
There are 38 chromosomes in a cat's somatic cell, which contain DNA molecules with genotypic information. Genotypic manifestations that are reflected in the external appearance of a living organism are called the phenotype. Phenotypic manifestations of kittensdiffer in color, size of the animal.
Genes in the offspring are paired - one gene from the female, and the other from the male. As you know, genes are divided into dominant (strong) and recessive (weak). Dominant genes are indicated by uppercase, Latin letters, recessive - lowercase. Depending on their combination, homozygous (AA or aa) and heterozygous (Aa) types are distinguished. The dominant gene appears both in the homo- and heterozygous state. The recessive gene will show its signs only in the homozygous type (aa). This genetic knowledge is useful in calculating the traits of future kittens from the phenotypic expressions of their parents. Here it is important to know which gene responsible for the manifestation of a particular trait is recessive or dominant.
Animal color genes are located on the X chromosome and are shown in the table below:
| a | Grey |
| b | Chocolate |
| c | Platinum, purple |
| d | Redhead |
| e | Cream |
| f | Tortoiseshell |
| g | Turtle blue cream |
| h | Turtle Chocolate |
| j | Tortoise Purple |
| Black | |
| o | Sorel honey |
| p | Tan Brown |
| q | Tortoise Red Brown |
| r | Tortoise tan |
| s | Smoky |
| w | White |
| y | Gold |
| x | Unregistered color |
Inherited traits
Cat chromosomes pass on certain hereditary traits to offspring, such as:
- ears - their location and dimensions, the size of the auricle;
- wool - color and character of the pile;
- eyes - pigment color;
- tail - its length, thickness;
- illness.
Breeders cull weak and defective individuals so that subsequent offspring are stronger, he althier and more perfect.
Coat color
In a thousand cat genes are those that are responsible for their color, and for a mutation that leads to a change in the color and structure of the coat. A non-sex somatic cell contains in the proto-oncogene elements of a mutation in coat color, which inhibits the migration of melanoblasts. Therefore, the latter cannot get into the skin, and the pigment, accordingly, does not reach the hair of the coat. This explains the animal's white coat.
Some melanoblasts manage to get into the hair follicles on the cat's head, then colored spots appear on the fur. These cells may well reach the retina of the eyes: with a small number of melanoblasts, the eyes become blue, and with a large number, the pupils of the animal will be yellow.
The same chromosome is also responsible for coat color. The usual structural form of melanoblasts gives the animal a striped color. There are also semi-dominant changes, for example, in the Abyssinian tebi. Homozygous individuals do not have stripes, the color is uniform, and heterozygous individuals with this mutation differ in stripes on the muzzle, paws, and tail. In the case of a recessive change, the transverse stripes on the animal's coat are deformed into irregular lines on its back, appearing as longitudinal powerful black stripes.
Gene mutation affecting the enzyme tyrosinase leads to albinism. This happens not only in cats, but also in other mammals.
Tyrosinase reduces its activity depending on the temperature of cats - the lower it is, the more active the enzyme. In such cases, there is intense staining of the peripheral parts of the body: nose, paw tips and tail, ears in Burmese cats.
Mosaic cats
The set of cat chromosomes responsible for coloring is located on the X chromosome. Mosaic cats are not uncommon, but there are still fewer three-colored cats than two-colored ones.
In this case, the color is determined by the alleles of the gene O:
O - affects the yellow (or red) color of the fur;
o - responsible for the black color.
Tortoiseshell cats are heterozygous for this gene, their genotype is Oo.
Yellow and black spots they develop as a result of random inactivation in the early embryogenesis of the X chromosome by the O or o allele. Cats can only be homozygous for this trait (OU - red or OU - black).
Tortoiseshell cats are extremely rare - they are characterizedchromosomal constitution XXY and genotype OoY. This is the reason for the rare birth rate of mosaic cats (or tortoiseshell cats).
Inheritance of the tricolor coloration of cats:
Black color - XB gene - genotype - XB XB; HVU;
Red color - Xb gene - genotype - Xb Xb; HYU;
Tortoiseshell color - gene - XB; Xb - genotype - XB; HH.
White color cats
White color at the chromosomal level is the absence of pigment. Pigment cells are blocked by one gene - W. If there are recessive traits of this gene (ww) in the genotype of cats, then the offspring will be colored, and if there is a dominant trait (WW, Ww) and at the same time there will be many other designations of gene chromosomes in the genome of cats (BOoSsddWw), then we will still see a completely white cat. However, such cats can carry both spotting and patterning, but only if the offspring does not inherit the W gene.
Chromosomes of a cat with Down syndrome
This disease occurs not only in humans, but also in animals, cats are no exception.
There are many stories and photos from the life of such animals on the Internet. As well as people, such animals may well live and be active, but visually they differ from he althy ones. Like people, these animals need some care, care and treatment.
To the question: "How many chromosomes does Down's cat have?", one can definitely answer: 39.
Down Syndromeoccurs when another extra chromosome appears in the gene set of chromosome molecules - odd. In the case of cats, this is chromosome 39.
A cat with an extra chromosome is rare in nature for the simple reason that the animal does not use drugs, alcohol, does not smoke, i.e. the provoking causes of the gene mutation are excluded. But still, this is a living organism, sometimes there are failures in it too.
Scientists and biologists do not have a definite opinion about the extra chromosome. Some say that this cannot be, others say that it can, and still others say that this occurs when an animal is artificially bred as a test subject.
A cat with 20 chromosomes (the twentieth pair of chromosomes is extra) is found, but it has practically no chance of reproducing he althy offspring. This, of course, does not mean that such an animal cannot be loved. They are quite cute, but a little unusual, different, but still they are alive. For example, a cat with this syndrome (Maya from America) became the favorite of her owners (Harrison and Lauren). They created their own Instagram page for the cat, regularly posting her photos and videos. Maya has become a favorite of Internet users, she is quite active and cheerful, although she suffers from shortness of breath and constantly sneezes. But no one bothers her to live for her own pleasure and for the pleasure of her masters.
By the way, do not confuse the cat's Down syndrome with genetic mutations that lead to a physical change (deformation) of the animal's faces. This is more common in nature than Down's disease,and is due to crossing between cats-relatives (interracial crossing). If there are many animals of the same genus in the offspring, then sooner or later physiological changes will occur not only in the appearance of the animals, but will also affect their development as a whole. If breeders can control this, then the owners of cats running around the yards practically cannot track it. Some people throw out such offspring, others, on the contrary, treat this philosophically and also love their pets.
How many lives does a cat have?
Everyone knows that in 1996 the first cloning was carried out in the world (the famous sheep Dolly). Five years later, scientists cloned a cat, they gave her a name - Carbon Copy (in Russian) or Carbon Copy (this is Latin).
For cloning, a cat of tortoiseshell gray-red colors - Rainbow was taken. Eggs and somatic cells were extracted from Rainbow's ovaries. Nuclei were removed from all eggs and replaced with nuclei isolated from somatic cells. Then, electroshock stimulation was performed, and after that, the reconstructed eggs were transplanted into the uterus of a gray tabby cat. It was this surrogate mother who gave birth to Carbon Paper.
But Carbon Paper didn't have red spots. During the study, it was possible to find out the following: in the genome of a cat (female) there are two X-chromosomes that are responsible specifically for the color of the animal.
Both X-chromosomes are active in the fertilized cell (zygote). In the process of cell division and further differentiation in all cellsbody, including future pigment cells, one of the X chromosomes is inactivated (i.e., the cell loses or greatly decreases activity). If a cat is heterozygous (for example, Oo) for the color gene, then in some cells the chromosome carrying the allele of red color can be inactivated, in others - carrying the allele of black color. Daughter cells strictly inherit the state of the X chromosome. As a result of this process, the tortoiseshell coloration is formed.
When cloning a cat in the nucleus of a reconstructed egg, extracted from a normal somatic cell of a tricolor cat, there was no complete reactivation (restoration of viability or activity) of the disabled X chromosome.
Complete reprogramming of the nucleus of chromosomes does not occur when cloning a living organism (in this case, a cat). It is likely that this is why cloned animals get sick and cannot always produce he althy offspring. The copy is still alive. She became a mother of three adorable kittens.
Conclusion
This article looked at how many chromosomes a cat has, what they are "responsible for" and how they affect the animal.
To the question: "How many chromosomes are in a cat's egg?", the answer is unequivocal - 19 chromosomes. Cat color genes are located on the X chromosome. Melanoblasts (i.e. cells that give rise to melanin-producing pigment cells) do not yet contain pigment and are responsible for the pattern on the fur coat and for the color of the iris. The enzyme tyrosinase is responsible for the manifestation of albinism, but this enzyme should not be confused with the W gene (gives a white coat color).
Mosaic cats haveXXY chromosome constitution and OoY genotype, so they are not so common. Allele (section) of the mosaic cats gene - Oh, it is he who is responsible for the mosaic coloration.
In the chromosome set, failures or mutations of genes sometimes occur, then either cats with Down syndrome or cats with a deformed appearance are born. The second can be predicted, but the first is much more difficult. Perhaps because this phenomenon is not the most common and there are not so many studies of its causes.
A cat, like any other living organism, can be cloned, and, as practice shows, such animals are quite viable.
In general, genetics is a very interesting and informative science that studies the patterns of heredity and variability transmitted from parents to descendants. Having deciphered the genes of an animal, one can understand what kind of offspring it will have, one can exclude gene mutations, and bring out pure breeds. And the motto of cat breeders is: "Pure breeds - he althy cats."
