Question

Explain sex determination in human beings.

Answer 1

Hint: Animals show sexual dimorphism, an individual can be either male or female. In most of these cases, sex is determined by the sex chromosome. There are mainly two types of chromosomes, sex chromosomes, and autosomes.

Complete answer:
The sex of eutherian animals is determined by its sex chromosomes. An organism has an XX or XY karyotype, this is the basis for primary sex determination. Two X chromosomes are present in all of their somatic cells in the case of females whereas in the case of males there is one X chromosome and one Y chromosome. Individuals who develop as males have a Y chromosome no matter how many X chromosomes they have, whereas individuals without a Y chromosome develop as females. Thus the primary sex determination is based on the presence of the Y chromosome. Primary sex determination is the determination of the gonads i.e the egg forming ovaries and sperm forming testes. In contrast, the secondary sex determination is the determination of the male or female phenotype by the hormone produced by the gonads.

Note: Human body cells have 46 chromosomes, 22 pairs of autosomes, and 2 sex chromosomes. When meiosis occurs in females, the two X-chromosomes pair and get segregate like autosomes so that each female gamete receives one X chromosome, Hence the female is said to be homogametic sex. During meiosis in males the X and Y chromosome pair and segregate so that half gamete receives X and the other half receive Y. Therefore the male is said to be heterogametic sex.