Question

Хромосомы определяющие половые отличия мужских и женских особей

Answer 1

XY - у мужчин, XX - у женщин

Answer 2

У птиц: ХУ-это женщина, а ХХ-это мужчина
у мухи дрозофилы: чем больше Х тем больше женщина
У человека и животных: ХХ-женщина, ХУ-мужчина:)

Answer 3

Chromosomes Determining Sexual Differences in Male and Female Individuals

The determination of sexual differences in male and female individuals is primarily influenced by the presence of specific chromosomes. In humans, these chromosomes are known as sex chromosomes, and they play a crucial role in determining an individual's biological sex.

1. Sex Chromosomes: - Humans typically have 23 pairs of chromosomes, including two sex chromosomes. - The sex chromosomes are labeled as X and Y chromosomes. - Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY).

2. Role of Sex Chromosomes: - The sex chromosomes carry genes that are responsible for the development of sexual characteristics and reproductive functions. - The presence or absence of the Y chromosome determines the development of male-specific characteristics. - The X chromosome carries genes that are essential for both male and female development.

3. Development of Male and Female Characteristics: - During fertilization, the sperm contributes either an X or a Y chromosome, while the egg always contributes an X chromosome. - If the sperm carries an X chromosome and fertilizes the egg, the resulting zygote will have two X chromosomes, leading to the development of a female individual (XX). - If the sperm carries a Y chromosome and fertilizes the egg, the resulting zygote will have one X and one Y chromosome, leading to the development of a male individual (XY).

4. Gene Expression and Sexual Differentiation: - The presence of the Y chromosome in males triggers the expression of specific genes, such as the SRY gene (sex-determining region Y). - The SRY gene initiates a cascade of genetic events that promote the development of male reproductive structures and secondary sexual characteristics. - In the absence of the Y chromosome, the default genetic program leads to the development of female reproductive structures and secondary sexual characteristics.

5. Disorders of Sexual Development: - Variations in the sex chromosome composition or gene expression can result in disorders of sexual development (DSD). - DSD refers to conditions where an individual's chromosomal, gonadal, or anatomical sex is atypical. - Examples of DSD include Turner syndrome (45,X), Klinefelter syndrome (47,XXY), and Androgen Insensitivity Syndrome (46,XY).

In conclusion, the presence or absence of specific sex chromosomes, particularly the Y chromosome, plays a crucial role in determining the sexual differences between male and female individuals. The expression of specific genes on these chromosomes leads to the development of male or female reproductive structures and secondary sexual characteristics. However, it is important to note that variations and disorders of sexual development can occur due to chromosomal or genetic abnormalities.