What are Chromosomes?
Human somatic cells have 46 chromosomes, of which 44 (22 pairs) are autosomes, and the other two play a decisive role in sexual development, called sex chromosome. Humans are known to have X and Y sex chromosomes. Women's two sex chromosomes, which are exactly the same size and shape, are called X chromosomes. One male is the same as the X, and the other is much smaller, called the Y chromosome. The most important significance of the Y chromosome is to determine male gender. There is no other more important role. There are many important genes on the X chromosome. Women have two X chromosomes. Although men have only one X chromosome, women have no more than twice as many sex chromosome gene products. The phenomenon that male and female X-linked gene products are equal is called dose compensation.
- Chinese name
- Sex chromosome
- Foreign name
- sex chromosome
- Decide
- Individual sex
- Features
- Genetic information
- Find the time
- 1902
- Meaning
- Maintaining gender balance
Basic Information
Sex chromosome sex chromosome and sex
- Sex chromosomes are directly related to sex determination. Human sex is determined by XX-XY type. Males are heterosexual chromosomes. The cells contain one X chromosome and the other is Y chromosomes. The sex chromosome composition is XY. The females are homosexual chromosomes and the sex chromosomes are XX Somatic cells contain two X chromosomes. When gametes occur, men can produce two kinds of sperm, X-type sperm containing X chromosome and Y-type sperm containing Y chromosome, and the number of both types of sperm is equal; whereas women can only form one type of egg with X chromosome. During fertilization, the X-shaped sperm combines with the egg to form a fertilized egg with a sex chromosome composition of XX and will develop into a female in the future; while the Y-shaped sperm combines with the egg to form a fertilized egg (also known as a zygote) with a sex chromosome composition of XY and develops male. So human sex is determined by sperm. In the natural state, the combination of different sperm and eggs is random, so the sex ratio of men to women remains roughly 1: 1.
Causes of sex chromosomal abnormalities
- 1. Maternal age
- The older the mother is, the more likely the offspring will develop chromosomal disease, which may be related to the aging of the mother's eggs.
- 2. Physical factors
- X-ray radiation and ionizing radiation can induce chromosome aberrations, and the distortion rate increases with the increase of radiation dose.
- 3. Chemical factors
- Many chemical drugs (such as anti-metabolic drugs, anti-epileptic drugs, etc.) and pesticides and poisons (such as benzene, toluene, arsenic, etc.) can cause increased chromosomal aberrations.
- 4. Biological factors
- Viral infections such as Toxoplasma gondii, cytomegalovirus, Epstein-Barr virus, mumps virus, rubella virus, and hepatitis virus can cause fetal chromosome aberrations.
- 5. Genetic factors
- Chromosomal abnormalities are related to heredity.
- 6. Autoimmune diseases
- Autoimmune diseases play a role in chromosome segregation.
Sex chromosomal sex chromosome abnormalities and diseases
- 1. Congenital ovarian hypoplasia
- It is one of the most common sexual dysplasias. It is clinically characterized by short stature, undeveloped breasts, and female genitalia in young girls.
- The sex chromosome lacks an X. Most single X chromosomes come from the mother. Chromosome deletion is mainly the result of non-separation of sex chromosomes during the formation of parent gametes. It may also be caused by abnormal structure of the sex chromosome, such as the long arm and short arm Xi (Xq) of the X chromosome, the short arm Xi (Xp), the long arm or short arm missing XXq-, XXp-, forming a circular chromosome r (X ) Or translocation. Deletion or chimerism of sex chromosomes not only affects the development of gonads and reproductive tracts, but also affects physical characteristics.
- 2. Spermatoderm dysplasia
- Also known as Klinefelter Syndrome, it is a sexual developmental abnormality with an abnormal number of chromosomes in men. The typical karyotype is 47, XXY, and there can also be chimeric. Most patients are the result of chromosomal segregation during ovulation, rather than chromosomal segregation during mitosis during the first cleavage of XY zygotes.
- The patient had hypospadias at an early age, and during puberty she had a doctor, penis, and secondary sexual characteristics, or had breast development.