Sex Determination
Chromosomes act as the vehicle for transmission of hereditary characteristics. Each cell of a normal human beings contains 23 pairs of chromosomes. Out of which, the first 22 pairs are called autosomes and the final pair is called sex chromosomes. Autosomes are responsible to transfer the body features of the parents into the offsprings while the sex chromosomes are essential to determine the sex (gender) of the offspring. In normal conditions, sex of human beings is categorized as male and female.
Generally, sex chromosome of male is composed of XY chromosome and that of female is composed of XX chromosomes. A male can produce both X and Y sex chromosomes but a female always produces X sex chromosomes only.
At the time of copulation, the sperm ejaculated into the female reproductive part contains 50% X chromosomes and 50% Y chromosomes. On fusion with the ovum, produced by the females, only X or only Y chromosome fuses with an X chromosome of female.
If X chromosome (male gamete) fuses with X chromosome (female gamete), it results in the formation of XX sex-chromsome. As a result, a daughter is born.
If Y chromosome (male gamete) fuses with X chromosome (female gamete), it results in the formation of XY sex-chromosome. As a result, a son is born.
PUBLIC AWARENESS
Birth of a son or a daughter is dependent upon male gamete. If X chromosome from the male gamete fuses with female gamete, a daughter is born. If Y chromosome from the male gamete fuses with female gamete, a son is born. In traditional (patriarchal) societies, females are hugely criticized for giving birth to daughters which must be stopped.
Chromosomal Disorder
A normal human body cell contains 23 pairs of sex-chromosomes. In rare cases, the number of chromosomes in human beings can vary. Such an abnormal condition where the number of chromosomes in human beings is other than 46 is called chromosomal disorder.
Following are some examples of chromosomal disorders:
- Down’s Syndrome
There are 47 chromosomes in a human cell. The 23 pair of chromosomes are as usual. But, the 47th chromosome is a repition of the 21st autosome. As a result, there are three 21 autosomes in the human cell. Therefore, down’s syndrome is also called as trisomy of 21.
Following are its symptoms:
Flat face, small broad nose, large furrow tongue, and upward slanting eyes. - Klinefelter’s Syndrome
There are 47 chromosomes in a human cell. The 47th chromsome is an additional X chromosome in the body of a male. A person having this syndrome has 22 pair of autosomes and XXY sex chromosomes.
Following are its symptoms:
Longer arms, legs, more fat, wide hips, learning disability, and abnormally tall. - Turner’s Syndrome
There are 45 chromosomes in a human cell, usually female. There are 22 pairs of autosomes and only one X sex chromosome. It is denoted by 45, XO.
Following are its symptoms:
Shorter body structure, less developed ovaries, short neck, etc.
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