How many chromosomes in humans?
Parents transmit inherited not only personal property and material values, but also their genes. All genes are stored in DNA, but retains the code — chromosome and therefore how many the person will depend on mental abilities, face shape, hair color and much more.
The emergence of the term
In the 19th century by the German botanist St. Chamberlain began studying cell division, the process he started with potted plants of tradescantia. In the process, he discovered the fact that before a cell splits into two, its core, which is also divided into two parts, resulting in formation of two daughter nuclei. But it was not the only discovery before the nucleus began to divide, it divided into small particles, which were like thin threads. They were of microscopic size they can be seen only by staining the cells with a special dye.
These microscopic threads were called chromosomes, if literally translate the word it means — painted body.
On the basis of the discovery of fission, and later other scientists found that the chromosome is an integral part of any plant or animal cell. Yet it was found that their number for the same species is not only vegetable, but the animal is always the same.
Scientists found that in a healthy human body cell contains 46 chromosomes.
Multiplication and division of chromosomes
Chromosomes begin to form during cell division. They form near me identical to myself, first they are located next to each other, and further when dividing cells they also share. It follows from this that in each new cell contains a full set of identical chromosomes. The reproduction of cells obtained by fusion of gametes, respectively, of the sperm and egg. This whole process of reproduction is called fertilization. Interesting fact, germ cells contain a set of chromosomes is 2 times less than the other cell in the body. For example, in humans 23 pairs, it turns out that merging the sperm and egg appears to the cell that contains 46 chromosomes, which store a part of data of the father and the same amount of data mother.
There are deviations in the number of chromosomes?
It is not strange, but in the world people are born with an unusual number of chromosomes, there are 2 types of violations is:
- Genome that mutations increase the total amount or only the number of chromosomes in one of the pairs.
- Chromosomal abnormalities occur in the process of restructuring cells in pairs, they can be rebuilt, both within and among themselves. For example, a person with a violation may be one of the genes, but in another there may be more than 6 couples. In the excitation process is not only change structure, but also the location itself pairs of chromosomes. Today, scientists are violations not only in the twenty-first, eighteenth, but in the thirteenth and twenty-third chromosome pair.
Genetic changes in down syndrome
This disease was described already in the late 17th century, but there were no detailed descriptions of the number of pairs contained in a patient. To date, statistical research concluded that in 1000 newborns have 2 children who are born with the disorder. Scientists identified the root cause of the disease syndrome in the 21st pair joins another pair of chromosomes, and their number in the aggregate, the result is 47. The most common cause of birth of children with such disabilities are: diabetes or advanced age of the parents may also adversely affect radiation.
In most cases, children born do not differ from healthy, but there are still small differences. Unlike healthy children is mental retardation, abnormal, large tongue, enlarged folds over the centuries, children have narrow and broad forehead, and ears are most often irregular in shape. Life expectancy with this disease is not more than 50 years, as there are additional physical abnormalities. For example, male patients have abnormalities of genital organs development and problems with the cardiovascular system. Female patient, though able to have offspring, but do not always dare to do this, since the case is the genome of the mother.
Genetic disorders in the syndrome of Poitou
Deviation occurs in the twentieth chromosome, it joins another pair, is that in addition to attach additional pairs can occur in their construction. The risk of this disease is very minimal, it is diagnosed at birth. Signs can include: a greater number of fingers on the hands and feet, small size of the eyes and a cleft palate or lip. Babies born with this disease do not survive more than 4 years, as there are violations in development of not only sexual and internal organs and brain.