Comparatively, sexual reproduction is much more complex than asexual reproduction. Sexual reproduction is a slow and lengthy process. The process begins with gamete formation in the male and female body. 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 multi-cellular embryo which eventually develops into a complete fetus. But we have to wait another 9 months to deliver this baby.
Let’s have a glimpse into sex determination, who determine the gender of the baby- father or mother.
Sex Determination: Boy/ Girl
Fertilization is the process in which two gametes (sex cells) – sperm and ova – fuse together to form a new cell called zygote. During this unbiased event, all genetic information from parents to the child has been transferred. Also, the gender of the child is determined and the father of the child is responsible for the sex determination.
Chromosomes are a thread like structure 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. 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.
- If the sperm with X chromosome fertilizes the ovum of X chromosome, the zygote would have XX chromosomes and the child will be a girl.
- If the sperm with Y chromosome fertilizes the ovum of X chromosome then the zygote would have XY chromosomes and the child will be a boy.
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