Question

Explain sex determination in human beings.

Answer 1

Hint: Humans show a type of male heterogamety which is also shown by some insects where females produce similar gametes and males produce dissimilar gametes.

Complete answer:
Human beings show XX-XY type of male heterogamety. Both females and males have the same number of chromosomes. Out of 23 pairs of chromosomes, 22 Pairs are exactly the same in both males and females. These are called autosomes. A pair of X chromosomes are present in females and in males X and Y chromosomes are present which are dominant. During spermatogenesis, two types of chromosomes are being produced, half of the sperms with X- chromosome and another half of the sperms produce the Y chromosome along with autosomes.
In females, all the ava are with the X chromosome. There is an equal probability of fertilization of ova by either sperm with X chromosome or sperms with a Y chromosome. If the fertilization is done with the sperm having an X chromosome then develops into a female, if the fertilization is with a Y chromosome, the zygote develops into a male. This shows evidence that there is an equal probability of developing either male or female.

Additional Information:
-Sex of a species in which the sex chromosomes are not similar is referred to as heterogamety. it is a type of sex determination.
- It includes male heterogamety and female heterogamety. If males produce similar gametes and females produce different gametes it is called female heterogamety. If females produce similar gametes and males produce different gametes it is called male heterogamety.
-Male heterogamety is of two types namely XX-XO and XX-YY(XX refers to a female). Female heterogamety is of two kinds ZO-ZZ and ZW-ZZ.

Note: Sex chromosomes are also called allosomes.
Henking discovered sex chromosomes and he named chromosome as the X chromosome
Stevens and Wilson identified the Y chromosome which is considered as a sex-determining chromosome.