Explain the sex determination mechanism in humans. How is it different in birds
Sex determination in humans:
Human beings exhibit male heterogamy. In humans, males (XY) produce two different types of gametes, X and Y. The human female (XX) produces only one type of gametes containing X chromosomes. The sex of the baby is determined by the type of male gamete that fuses with the female gamete. If the fertilizing sperm contains X chromosome, then the baby produced will be a girl and if the fertilizing sperm contains Y chromosome, then the baby produced will be a boy. Hence, it is a matter of chance that determines the sex of a baby. There is an equal probability of the fertilizing sperm being an X or Y chromosome. Thus, it is the genetic make up of the sperm that determines the sex of the baby.
Sex Determination in birds:
The sex chromosomes in birds is determined as Z and W. The male is homomorphic (ZZ) and the female is heteromorphic (ZW). W chromosome carries female sex determining genes and duplication of Z chromosome indicates male sex. So, in case of chicks, the sex is determined by teh egg and not by the sperms.
Human beings exhibit male heterogamy. In humans, males (XY) produce two different types of gametes, X and Y. The human female (XX) produces only one type of gametes containing X chromosomes. The sex of the baby is determined by the type of male gamete that fuses with the female gamete. If the fertilizing sperm contains X chromosome, then the baby produced will be a girl and if the fertilizing sperm contains Y chromosome, then the baby produced will be a boy. Hence, it is a matter of chance that determines the sex of a baby. There is an equal probability of the fertilizing sperm being an X or Y chromosome. Thus, it is the genetic make up of the sperm that determines the sex of the baby.
Sex Determination in birds:
The sex chromosomes in birds is determined as Z and W. The male is homomorphic (ZZ) and the female is heteromorphic (ZW). W chromosome carries female sex determining genes and duplication of Z chromosome indicates male sex. So, in case of chicks, the sex is determined by teh egg and not by the sperms.