Chromosome is the structure that contains nucleic acid and is responsible for the storage, execution and transfer of information on hereditary characteristics. At its core is a DNA molecule – deoxyribonucleic acid.
Inside the nucleus the chromosomes are composed of long chains of genetic information. A gene is unit of heredity of living beings, the DNA segment.
Chromosomes are called the particles of heredity, they are in pairs – a human has 23, that is the whole hereditary information of the individual contains 46 particles.
There are two types of chromosomes:
- eukaryotes contain DNA molecules in the nucleus and mitochondria;
- prokaryotes – containing DNA structures are nuclear-free cells.
The number of chromosomes in animals
Cats have a number of pairs of chromosomes 19 and the total number of particles of heredity – 38. Each gene is responsible for a separate feature of the body, and many of them interact with each other and one feature can be controlled by several genes, so they are difficult to study.
Cells are formed from DNA and chromosomes. We can say that the chromosome is a DNA molecule and it is a lot of genes. The number of chromosomes in different animals may coincide, for example, the pig has the same number of them as cats – 38. The smallest number of particles of heredity seen in earthworms (2). Ants are also the Champions in this respect: females of particle 2, and males and did 1.
The last pair of chromosomes in humans a male has the form XY and women have XX. Similarly is the case in higher animals, including cats and dogs.
But the number of molecules for each species, though constant, but different in quantity for each organism:
- hare – 48;
- crayfish – 196;
- monkey – 54;
- cow – 60;
- the horse 64.
Among animals the most numerous chromosome set in hamsters (92), slightly less than the hedgehogs (90). The minimum number of such molecules have kangaroo – 12. Samples of frozen tissues of a mammoth found that he had 58 chromosomes.
Particles of heredity cats
The study of heredity and the number of chromosomes has been the science of genetics. The number and structure of the particles of heredity for each species constant parameter and it is called the karyotype. Any deviation can cause hereditary diseases, the emergence of an inactive species or a new species. All pairs of chromosomes, and their cats have 19, similar in shape and appearance.
The only exception is one pairthat is responsible for sexual characteristics – she has a particle of heredity of various sizes, which determines the female sex chromosome X larger, and male, is smaller. From their combinations during fertilization and gender depends future individuals.
Information embedded in DNA is called the genotype, and the outer expression of the characteristics – the phenotype. All genes are paired – one from a cat and cats. One of them is the dominant, stronger and more determining manifestation of its signs in kittens. The other recessive, it is dominant and oppressed veiled demand. And when converge two recessive – cat and cats, you get kittens, unlike any one nor the other. For example, white cats and black cat may appear young red color, if both the recessive gene responsible for red color.
Feline inherited traits are the following:
- the dimensions and contour of the ear, the location of the ears;
- the coloration of the coat and length of villi;
- pigmentation of the eye;
- the length of the tail and other.
The culling of defective individuals is done in order to maintain the purity of the breed based on the analysis of chromosomal set. It is important to keep records of deviations of the detected violations, to try to influence the correction of anomalies through proper feeding and training of cats. Thus, it is possible to reveal the oppressed genes that can affect improvement of the breed or to give impetus to the creation of a new one.
The coloration and pupils
20 years ago the map of the hereditary particles cats had only dozens of genes, and today there are thousands. Among them are responsible for the coloration of units, and the mutations which lead to changes in coat color. For example, one physical particle – asexual, contains the elements of a mutation in color of six: is it in proto-oncogene and inhibits the migration of melanoblast. In the result, the latter do not have the ability time to get to the skin, and thus the pigment does not reach the hairs of the coat. Why is a white woolen blanket.
If some melanoblast penetrate into the hair follicles on the head of a cat, this causes the appearance of colored spots. Mutational melanoblast can reach the retina of the eye, but their number may be different in small including color becomes blue, and if a lot of the pupils are yellow.
In the same chromosome – particle of heredity is responsible for the drawing of the coat gene. Its normal structural form creates a striped color, the bands may be interrupted or to be continuous. Sometimes predominante change, for example, Abyssinian täby. Homozygous individuals with a couple of the usual structural forms for this change are generally without stripes and coloring of wool, they have a uniform. But the heterozygous individuals from the mutation of stripes appear on the muzzle, paws and tail. When change is recessive, the bands are deformed in the line of irregular shape and on the back of the cats appears powerful longitudinal stripe of black.
Mutations in the gene affecting the enzyme tyrosinase, a cause of albinism, occurring not only in cats but also in other species of mammals. A decrease in the activity of tyrosinase is temperature dependent cat – the smaller, the more active the enzyme. From this comes a more intense staining of the peripheral parts of the body: the nose, tips of paws and tail, the ears of the Burmese cat.