Sex Determination - Boy Or Girl

Table of Contents

• What is Sex Determination?
• What is Fertilization?
• What are Chromosomes?

A sex-determination is the biological system that determines the development of sexual characteristics in an organism. There are two different types of sexes – male and female. Chromosome plays an essential role in determining the sex of an individual.

Let us have a glimpse into sex determination and who determines the gender of the baby- father or mother.

Comparatively, sexual reproduction is much more complicated than asexual reproduction. Sexual reproduction is a slow and lengthy process. The process begins with gamete formation in the male and female bodies. Through sexual intercourse, these male and female gametes meet and fuse to form a unicellular zygote. It continues with multiple divisions of the zygote to form a multicellular embryo which eventually develops into a complete fetus. The entire process takes nine months to deliver a baby.

Fertilization is the process in which two gametes (sex cells) – sperm and ova – fuse together to form a new cell called the zygote. During this unbiased event, all genetic information from the parents to the child has been transferred. Also, the gender of the child is determined, and the father of the child is responsible for sex determination.

Chromosomes are a thread-like structures holding genetic information. It is present in the cell nuclei. A normal cell contains 23 pairs (46n) of chromosomes. Out of these, one pair (2n) is sex chromosomes. Sex chromosomes are denoted as X and Y. A male cell contains XY sex chromosomes, while a female cell contains XX sex chromosomes.

A gamete contains only 23 chromosomes (23n). A sperm contains either an X or Y chromosome, i.e. there will be two sets of sperms. One set of sperm consists of only X chromosomes, while another set consists of only Y chromosomes. An ovum always contains an X chromosome. The sex of the child depends on the kind of sperm that fuses with the ovum.

During sexual intercourse, the father ejects both types of sperms, i.e. X chromosome and Y chromosome sperms.

1. If the sperm with an X chromosome fertilizes the ovum of the X chromosome, the zygote would have XX chromosomes, and the child will be a girl.
2. If the sperm with the Y chromosome fertilizes the ovum of the X chromosome, then the zygote would have XY chromosomes, and the child will be a boy.

To learn more about sex determination with the interactive video lessons, visit BYJU’S.