Few think about the genetic predisposition of the acquired pet. In the article I will tell you how many chromosomes a cat has. I will describe what this structure represents. Let me explain the importance of the karyotype and chromosomal complex. I will explain the principles of heredity. I will analyze whether there are animals with Down syndrome.
What are chromosomes
A chromosome is a structure in the cell nucleus that carries genetic information. Necessary for the storage of such, transmission from generation to generation and implementation of the offspring. Consists of molecules and histone proteins, connected in the so-called complexes.
Under the microscope, the body can only be seen when cell division.
X - much more.
If cells with X chromosomes are involved in fertilization, a woman will develop. In the case when one of the Y chromosomes, there will be a cat.
Karyotype and chromosome complex
The number and structure are fixed. The researchers gave him the name of the karyotype.
Contains features associated with inherited traits and properties. Any changes are the cause of inherited diseases and the appearance of babies with pronounced inconsistencies and pathologies, sometimes incompatible with life.
A number of breeds of expensive Murok bred artificially, which does not detract from the merits of cute creatures (chausi, toyger, savanna, American Curl, etc.).
Crossbreeding scheme with cats
Analysis of the kit plays an important role in the selection of high-quality specimens and the culling of individuals with defects. That is what determines the preservation of the purity of the breed.
The duty of the owners is to provide truthful information about the cubs and their parents, without exaggerating or, on the contrary, hiding significant factors.
Principles of heredity cats
The information embedded in the chromosomes is the genotype. In turn, the external manifestations of certain features is called the phenotype.
Genes are arranged in pairs (one each from mother and father) - alleles and differ in the following subspecies:
- Dominant, that is, predominant. Due to this gene, certain signs of appearance are inherited by the offspring of the first generation.
- Recessive. Being depressed dominant, hidden for some time. Recessive genes, combined with each other, give offspring, unlike parents.
Consider the inherited traits:
- color,
- eye color
- wool structure
- the size, shape and setting of the ears,
- tail length and thickness
- the structure of the body and limbs.
Down syndrome in cats
In the cat family, as in humans, there are individuals with an extra pair. By analogy with a human disease, pathology is referred to as Down syndrome.
Less energetic than healthy peers. Paws shortened. The nose is flattened. The corners of the mouth are lowered, the eyes are planted wrong. Often, patients suffer from squint or weak eyesight. Immunity weakened. They get sick more often than usual relatives.
Cat with Down Syndrome
Learning to give in with difficulty. For the main part of the poor, the elementary tray is an incomprehensible science.
Some scientists fundamentally disagree with this formulation, since the disease is characteristic of Homo sapiens. As a result, the mutations of the 21st pair are presented not in two, as expected, but in three copies.
However, the animals endowed with extra chromosome, called the Downs.
Attitudes toward such creatures are twofold. Someone feels disgust and considers it necessary to destroy the defective offspring.
Others, on the contrary, feel sorry. Take from shelters, care and cherish.
In fact, to understand the features of the set of your favorite pet is quite simple.
The main thing to follow simple rules: do not cross individuals that are in close relationship.
Eliminate mating with individuals with birth defects. Then the kittens will be born full-fledged, strong and beautiful, and the frustrated owner will not have to decide the fate of the rogue.
Genome and chromosomes
It’s extremely difficult to talk about how many chromosomes a cat has without basic knowledge of genetics.
The genome is a structure that contains genetic information about the body. Almost every cell contains a genome. But the chromosome contains all the information about the structure of the cell. A 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 transmitted to the future generation.
A chromosome is a 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, the implementation of a genetic program for the development of a living organism.
There are two types of chromosomes in different organisms:
The eukaryotic type is characteristic of living organisms (eukaryotes), whose cells contain the nuclear envelope, DNA molecules in the nucleus and mitochondria.
Prokaryotic type - occurs in organisms with no nuclear membrane in their cells, and DNA molecules are enclosed in histones (prokaryotes).
Externally, the chromosome is similar to a long string with stringed beads, each of which is a gene. In addition, the gene is on its strictly fixed part of the chromosome - the locus.
The number of chromosomes in animals
How many chromosomes are in cat 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 will be determined (in our case, the kitten).
To the question: "How many chromosomes are in a cat's cells?", Genetics gives an 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 invariable and individually for each species (for example, in dogs - 78 chromosomes, in horses - 64, in cows - 60, in the hare - 48). Recall that in humans the number of chromosomes is 46.
Heredity of cats
In the somatic cell of a cat there are 38 chromosomes that contain DNA molecules with genotypic information. Genotypic manifestations, which are reflected in the appearance of a living organism, are called the phenotype. Phenotypic manifestations of kittens vary in color, size of the animal.
The genes of 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 designated by uppercase, Latin letters, recessive - lowercase. Depending on their combination, homozygous (AA or aa) and heterozygous (Aa) types are distinguished. The dominant gene is manifested both in the homo-and heterozygous state. The recessive gene will show its symptoms only in the homozygous type (aa). This genetic knowledge is useful in calculating the signs of future kittens from the phenotypic manifestations of their parents. Here it is important to know which gene is responsible for the manifestation of a particular trait, is recessive or dominant.
Animal genes are located on the X chromosome, and are listed in the table below:
Inherited traits
Chromosomes of a cat transmit to posterity certain inherited traits, such as:
- ears - their location and size, the size of the auricle,
- wool - color and character of the pile,
- eyes are the color of the pigment
- tail - its length, thickness,
- diseases.
Breeders make the culling of weak and defective individuals in order to make the subsequent offspring stronger, healthier and more perfect.
Coat color
In a thousand genes of cats are those that are responsible for their color, and for the mutation leading to a change in the color and structure of the coat. A non-sexual somatic cell contains elements of mutation according to the color of wool in the proto-oncogene, which inhibits the migration of melanoblasts. Therefore, the latter can not get into the skin, and the pigment, respectively, does not reach the hair hair. This explains the white wool of the animal.
Some melanoblasts manage to get into the hair sacs on the cat's head, then colored spots appear on the fur. These cells can easily reach the retina: with a small amount of melanoblasts, the eyes become blue, and with a large number, the pupils of the animal will be yellow.
The same chromosome is responsible for coat color. The usual structural form of melanoblasts gives a striped animal color. There are also semi-dominant changes, for example, in the Abyssinian tebi. Homozygous individuals do not have bands, the color is uniform, and heterozygous individuals with such a mutation differ in bands on the muzzle, legs, tail. In the case of a recessive change, the transverse stripes on the fur of the animal are deformed into irregular lines on its back, manifesting itself in longitudinal powerful stripes of black color.
A gene mutation that affects the tyrosinase enzyme 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 smaller it is, the more active the enzyme. In such cases, there is an intense staining of the peripheral parts of the body: the nose, the tips of the paws and the tail, and the ears in Burmese cats.
Mosaic cats
The set of cat chromosomes responsible for coloring is localized on the X chromosome. Mosaic cats - not uncommon, but still tricolor cats less than two-colored.
In this case, the color is determined by alleles of the gene O:
O - affects the yellow (or red) color of fur,
o - is responsible for black color.
Tortoise cats are heterozygous for this gene, their genotype is Oo.
Their yellow and black spots develop as a result of random inactivation in early X-chromosomal embryogenesis by the allele O or o. Cats can only be homozygous for this trait (OU - red or oU - black).
Tortoiseshell cats are extremely rare - they are characterized by the chromosomal constitution of the XXY and the UDU genotype. This is due to the rare birth rate of mosaic cats (or tortoiseshell cats).
Inheritance tricolor coloring cats:
Color black - gene XB - genotype - XB HV, HVU,
Color red - gene HB - genotype - ХЬ ХЬ, ХЬУ,
Turtle color - gene - XB, XB - genotype - XB, XB.
White color of cats
White color at the chromosome level is the absence of pigment. Pigment cells block one gene - W. If there are recessive traits of this gene (ww) in the genotype of cats, then the progeny will be colored, and if there is a dominant trait (WW, Ww) and there will be many other designations of gene chromosomes in the cats genome (BOoSsddWw ), then we will see anyway absolutely white cat. However, such cats can carry spotting and drawing, but only in the case that the offspring do 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.
On the Internet, "hangs" a lot of stories and photos from the life of such animals. No less than people, such animals can quite live and be active, but visually they differ from healthy ones. Like humans, such animals need some care, care and treatment.
To the question: "How many chromosomes does a Down cat have?" Can definitely be answered: 39.
Down syndrome occurs when an extra odd chromosome appears in the gene set of chromosome molecules. In the case of cats, this is the 39th chromosome.
A cat with an extra chromosome is rarely found in nature for the simple reason that the animal does not use drugs, drink, do not smoke, i.e. exclusion causes of gene mutation are excluded. But still, it is a living organism, sometimes it also fails.
Scientists and biologists have no definite opinion about the extra chromosome. Some say that this can not be, others say that it can, and others argue that this occurs during the artificial breeding of the animal as an experimental.
A cat with 20 chromosomes (the twentieth pair of chromosomes is superfluous) is found, but it has practically no chance to reproduce healthy offspring. This, of course, does not mean that such an animal cannot be loved. They are quite cute, but a bit unusual, some different, but still they are alive. For example, a cat with this syndrome (Maya from America) has become the favorite of its owners (Harrison and Lauren). They created their own cat page in Instagram, regularly posting its photos and videos. Maya has become the favorite of Internet users, she is quite active and cheerful, although she suffers from shortness of breath and constantly sneezes. But to live in their own pleasure and for the pleasure of their masters no one bothers her.
By the way, do not confuse down syndrome cats with genetic mutations that lead to physical change (deformation) of animal faces. This is found in nature more often than Down's disease, and is caused by mating between family cats (intergeneric mating). If there are many animals of one genus in the progeny, then sooner or later physiological changes will occur not only in the appearance of animals, but also affect their development as a whole. If the breeders can control this, then the owners of the cats running around the courtyards can hardly keep track of it. Some people throw out such progeny, others, on the contrary, relate to 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, the name was given to her - Carbon (in Russian) or Carbon Copy (this is Latin).
For cloning, a tortoiseshell cat of gray-red color was taken - Rainbow. Egg cells and somatic cells were extracted from the Rainbow ovaries. From all eggs, the nuclei were removed and replaced with nuclei isolated from somatic cells. Then stimulation was carried out with electric shock, and after that the reconstructed eggs were transplanted into the uterus of a gray striped cat. It is this surrogate mother who gave birth to a carbon copy.
But the carbon paper had no red spots. In the study, we managed to find out the following: in the cat (female) genome there are two X chromosomes that are responsible for the color of the animal.
In the fertilized cell (zygote), both X chromosomes are active. In the process of cell division and further differentiation in all cells of the body, including future pigment cells, one of the X chromosomes is inactivated (i.e., the cell is lost or the activity is greatly reduced). If a cat is heterozygous (for example, OO) by the gene for staining, then in some cells the chromosome that carries the allele of the red color can be inactivated, in others - the carrier allele of the black color. Daughter cells strictly inherit the state of the X chromosome. In consequence of this process, the tortoise color is formed.
When a cat was cloned in the nucleus of a reconstructed egg cell extracted from a normal somatic cell of a three-colored cat, there was no complete reactivation (restoration of viability or activity) of the turned off X chromosome.
The complete reprogramming of the chromosome nucleus does not occur when a living organism (in this case, a cat) is cloned. It is likely that this is why cloned animals are sick and can not always produce healthy offspring. The carbon copy is still alive. She became the mother of three charming kittens.
Conclusion
This article has examined 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 cell?", The answer is unequivocal - 19 chromosomes. Cat genes are located on the X chromosome. Melanoblasts (ie, cells that give rise to melanin-producing pigment cells) do not yet contain pigment and are responsible for drawing on the fur coat and for the color of the iris. The tyrosinase enzyme 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 have a chromosomal constitution of the XXY and ULV genotype, so they are not found very often. Allele (part) of the gene of mosaic cats - Oo, it is he who is responsible for the mosaic coloring.
In the chromosomal set, gene disruptions or mutations sometimes occur, then either cats with Down syndrome or cats with a deformed appearance are born. The second can be predicted, but the first one is much more difficult. Perhaps because this phenomenon is not the most common and research into its causes is not so much.
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 progeny it will have, we can exclude gene mutations, bring out pure breeds. And the motto of cat breeders: "Pure breeds are healthy cats."
Features of the karyotype and chromosomal complex of cats
The total number and the structural structure of the chromosome - a constant indicator characteristic of a certain species of animals, is called the karyotype. It is he who determines the inheritance of traits and properties of cats. В каждой клетке находится постоянное количество парных хромосом – у кошки их 38 (19 пар) – которые и задают внешность, состояние здоровья и характер животного.
При этом половые хромосомы содержат только половину хромосомного набора. Вторая часть присоединяется, образуя полноценную клетку, после оплодотворения яйцеклетки. 18 chromosomal pairs are exactly the same, but the last 19 pairs contain chromosomes of different sizes.
The random selection determines the sex of the kitten.
It regulates the sex of a cat:
- X - defines the birth of a female,
- Y - is responsible for the appearance of the male.
It is on what chromosomes the sex cells will contain that the sex of the conceived kitten depends. If, after fertilization, "met" cells, represented only by X chromosomes, the kitty will be born. When cells containing the X and Y chromosomes are joined, a cat will appear.
What is a chromosome and how many cats do they have
A chromosome is a special structure in the cell nucleus that contains hereditary information.
It consists of DNA molecules and proteins. DNA (deoxyribonucleic acid) stores and transmits information to subsequent generations and implements a program for the development of a species of animal organism. Chromosomes can belong to two types of living organisms:
- eukaryotes are almost all living organisms on the planet
- prokaryotes, the simplest unicellular, not having a well-formed nucleus.
Externally, the chromosome resembles a string with stringed beads, each of which is a gene.
The number of chromosomes and their structural composition for each biological organism is constant, and is called the karyotype, which determines the signs and certain features inherited by the organisms. Changes in the structure and number of chromosomes can cause diseases and mutations, leading to the emergence of individuals unable to survive, or vice versa, new species.
At the cellular level
In the cell there is always the same number of pairs of chromosomes, characteristic of a living being. They determine the appearance, character, state of health and even behavior.
The situation with the cells responsible for belonging to the floor is different. Each such cell (sperm or egg) contains only half the full set of chromosomes. After fertilization, the set is replenished. All paired chromosomes have the same structure and appearance. They are responsible for certain characteristics and properties of the population. One pair consists of chromosomes of different chromosomes, and is responsible for the sex of the living organism. The X chromosome is female, the Y chromosome is male. If two X chromosomes, female and male, are joined during the fertilization process, then a female individual will be born, if the X chromosome and the Y chromosome are involved, then the male one.
Modern genetics gives an exact answer to the question of how many chromosomes a cat or a cat has. The chromosome set consists of 19 paired chromosomes, therefore, there are 38 of them all in fluffy pets' cells. In any type of living organism, the number of chromosomes is constant. For example, dogs have 78 chromosomes, man has 46. Scientists have not yet fully solved the link between the number of chromosomes and the type of living being. For example, some types of ferns in the genome have up to 512 pieces.
The principle of inheritance and what do cats inherit?
Genetic information transmitted from ancestors is called a genotype. Its external manifestations of the phenotype. Genes are connected in pairs, one from each parent and can include dominant - strong, signs of which will manifest in the offspring, recessive - weak, which remain in the body in a latent state. The combination of recessive genes obtained from parents can lead to the appearance of a descendant, not like them. A black cat and a smoky cat may have cream kittens if they have a cream recessive gene present.
Chromosomes transmit to the descendant information responsible for:
- the location, shape and size of the ears,
- color, length, structure of the coat,
- the shape, length and thickness of the tail,
- diseases.
Patterns of gene inheritance are used by specialists to breed cat cats with specific features. But it would be erroneous to believe that this requires only knowledge of the genes, for which features they are responsible, and the fundamentals of breeding work. In practice, it is necessary to know the principle mechanisms of the work of genes that have not yet been sufficiently studied.
At the same time, it complicates and expands the possibilities of breeding new breeds of a combination of genes that 20 years ago were only about 20, and today there are more than 2 thousand. Of paramount importance in the selection and rejection of individuals for pedigree breeding is the consideration of the complex of chromosomes of cats. This takes into account all the deviations found in it, as well as flaws in appearance.
Sometimes mutations occur in a set of chromosomes, and cats are born with deformities of appearance or with Down syndrome. It is possible to give a forecast regarding the first phenomenon, but it is more difficult with the second, since there are not so many studies of the possible origins of this disease.
Genetics is a fairly young science that studies the mechanisms of inheritance of certain traits by living organisms, as well as the laws and laws of this inheritance. Deciphering the cat's gene helps to find out how many chromosomes are in cats and other animals, what offspring the individual will bring, to prevent the continuation of negative mutations and to help keep the breed clean.
Interesting about cats collected in this video
