What Is an X Chromosome?

The X chromosome is a special sex chromosome in the XY-type sex-determining organism's genome. When a female has the same sex chromosome, the female chromosome is called an X chromosome. In gender determination, XX is female and XY is male.

x chromosome

1.X chromosome is more complicated

Shakespeare said: "Not only are women so different from men, the differences between women are incredible! Women, really unpredictable creatures." A research report published by the British "Nature" magazine pointed out From a perspective, women are indeed more complicated than people think, but men are a group of simple creatures. If you have met a man, you have met all men.

According to the author of the study, Duke University geneticist Huntington Wellard said: "Our poor group of men has only 45 chromosomes in operation, and women have a complete 46 chromosomes for them to show their charm. "It is worth mentioning that their 46th chromosome, the sex chromosome, is also an X chromosome."

Their discovery can help people understand the reasons for differences in behavior and characteristics between men and women. As we all know, women's psychology is more complicated than men's. The reason is not only that their "software" of the nervous system and physical system is more complicated, but also that they have A more complex "hardware" material basis than men.

The human body is made up of billions of cells. Each somatic cell has 23 (46) chromosomes, 22 of which are autosomal. The autosomes of men and women are exactly the same. The remaining pairs are called sex chromosomes and are different for each sex. The X chromosome representing a female is a full-size, obviously normal chromosome; the Y chromosome representing a male is a small dot. And as a matter of course, the X chromosome can still carry the genes necessary for survival, because regardless of men and women, the X chromosome will be inherited. Humans are more dependent on the X chromosome than other chromosomes. The Y chromosome determines our sex, but the X chromosome determines whether we can exist. The X chromosome is robust and powerful, and its main role is not to carry a single gene.

People generally think that 15% of the genetic factors (about 200 to 300) on a woman's second X chromosome are obedient, dull, and "inactive", and joked that they are lying lazily on a Victorian couch and faint Sleepy. However, new research shows that these genetic factors are positive, and because of their existence, women are far more prominent in their genetic performance than men. "The X chromosome is undoubtedly the most unusual in the human genome in terms of genetic models, unique biology, and links to human diseases," said Dr. Mark Rose, who is involved in sequencing the X chromosome.

2.X chromosome lets genetic diseases pass from male to female

With the rapid development of genetics, more than 3,000 genetic diseases have been discovered, about 250 of which only occur in men, and women have no or few diseases. There are 23 pairs of chromosomes in human cells, of which 1 pair (2) are sex chromosomes that determine sex. Females are XX and males are XY. There are more than 50,000 genes on the chromosome that determine various traits of the human body. If the genes are mutated, diseases can occur and they can be passed on to future generations.

If the disease-causing gene is on the sex chromosome, it will have sex inheritance. The pathogenic gene is on the X chromosome, which is called X-linked or X-linked genetic disease. Because it is difficult for a woman to encounter a disease at the same location on two chromosomes, one X-chromosome pathogenic gene can often be masked by the normal gene on the other X-chromosome, so it does not show symptoms. Men are different. There is only one X chromosome. If there is a disease-causing gene on it, there is no corresponding normal gene to cover up, so it becomes ill.

There are many diseases inherited only to men, such as red-green blindness, duchenne progressive muscular dystrophy, broad bean disease, hemophilia, congenital agammaglobulinemia, hereditary deafness, hereditary optic atrophy, and autosomal Sexual genetic polycystic kidney disease (ADPKD) and so on. ^[3]

3.X chromosome enhances female immunity

Dr. Claude Liebel from the University of Ghent led a research team to draw a detailed map of all the tiny RNAs on the X chromosome. MicroRNAs, as the name suggests, are small RNAs, consisting of approximately 21 to 25 nucleotides. Previous research has shown that microRNAs carry genetic instructions that act on the cell's "protein factory," thereby regulating immune function and suppressing cancer.

Statistics show that humans, like other mammals, have a longer life expectancy than men, and are more resistant to sepsis, infections, or trauma, which stems from the X chromosome. 10% of all microRNAs found on the gene sequence are on the X chromosome.

Eleanor Fish, a professor of biology at the University of Toronto in Canada, said: "Compared to (male) one X chromosome and one Y chromosome, (female) two X chromosomes have obvious advantages."

MicroRNAs play an important role in regulating proteins that affect cell growth, cancer, and immune response. They can inhibit the proteins that trigger cancer, and can also strengthen the proteins that inhibit cancer. For women, if one gene on the X chromosome is associated with a mutation in the immune system, the other X chromosome can serve as a backup; in contrast, men have only one X chromosome.

From a biological perspective, this gender difference is determined by evolution, because females or females are the key to the survival of a species, and they need sufficient resistance to infection during pregnancy and parenting. ^[4]