Sex determination in human

Sex determination in human

In human male sex chromosome is 'XY', where as in female sex chromosome is XX. During gamete formation in male half of the sperm contain 'X' chromosome while other half contain 'Y' Chromosome. In female all gametes contain only one type of chromosome that is 'X'. Thus when a male gamete i.e. sperm carrying 'X' chromosome fertilize an ova, the zygote develop into female. When a sperm carrying 'Y' chromosome fertilizes an egg, zygote develops into male.
»   Barr body is found in female somatic cells.
»   Fertilization is done in test tube but further development takes place inside mother womb in test tube baby.
»   Sometime sex determination is regulated by environmental factor. In some reptiles temperature determine the sex at which the fertilized egg is incubated.
»   In human each cell contains 46 chromosomes. Any addition or removal in the number of sex chromosome or autosome cause genetic disorder.

1. Klinefelter Syndrome

When a male have an extra X or Y chromosome in, sex, chromosome then the condition will be XXY or XYY instead of XY. The male individual with this syndrome have masculine development but feminine development is not completely suppressed and the individual became sterile.
In female when extra X chromosome is present instead of XX they show normal development but limited fertility. Mental retardness is also seen in this type of syndrome. Number of chromosome became 47 instead of 46.

2. Turner's Syndrome

When female has single sex chromosome (XO) their ovaries are rudimentary, lack of secondary sexual character.

3. Down's Syndrome

When an extra chromosome is added to 21st autosomal chromosomes this lead to develop Down's syndrome. In this syndrome person became Mangolism. The person is mentally retarded, eyes protruded an irregular physical structure is present.

4. Patau's Syndrome

This type of syndrome is develop by an addition of autosomal chromosome in 13th chromosome. There is a cut mark in the lip and person is mentally retarded.

5. Sickle Cell Anaemia

In this disorder erythrocytes destroyed more rapidly than normal leading to anaemia. These occur due to change in 11th autosomal chromosome.

6. Phenylketonuria

It is an in born error of metabolism which result in mental retardation cause due to change in 12th autosomal chromosomes.

7. Haemophilia

Gene responsible for this disorder is linked with sex chromosomes. This disease lead to failure of blood clotting.

8. Color blindness

This disorder lead to failure to distinguished red & green colour. The gene responsible for this disease is situated on sex chromosomes.