Question

Give a brief account on sex determination in human beings.

Answer 1

A sex-determination system is a biological system that determines the development of sexual characteristics in an organism. In human beings, sex is determined by genetic inheritance. Genes inherited from the parents determine whether an offspring will be a boy or a girl. Humans have a total of 46 chromosomes. Half of them come from the mother and the other half from the father. Out of these 46 chromosomes, 44 are autosomes and 2 are sex chromosomes. A sex chromosome that carries the genes for male characters is called the Y chromosome and one which carries the genes for female characters is called the X chromosome. So the chromosomes in woman are 44 + XX and the chromosomes in man are 44 + XY. During gamete formation, the normal diploid chromosome number becomes a haploid condition. All the eggs of a female have 22 + X chromosomes and males produce two types of sperms i.e, one type contains 22 + X composition and the other in 22 + Y composition. If a Y bearing sperm fertilizes the egg, the zygote has the 44 + XY composition and the resulting embryo grows to be a boy. When an X bearing sperm fertilizes the egg, the resulting zygote has the 44 + XX composition and this embryo develops into a girl. So the sex is always determined by the other sex chromosome that they inherit from the father.