Sex of baby
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 spermcarrying ‘X’ chromosome fertile an ova,the zygote develop into female.when sperm carrying ‘Y’ chromosome fertilizes an egg,zygote develops into male.
Sometime sex determination is regulated by environmental factor.In some reptiles temperature determine the sex at which 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.
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 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.
when female has single sex chromosome (X0) their ovaries are rudimentary,lack of secondary sexual character.
When an extra chromosome is added to 21st autosomal chromosome 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.
This type of syndrome develop by an additional of autosomal chromosome in 13th chromosome,there is cut mark in lip and person is mentally retarded.Diseases due to change in gentical constituent of chromospome.
Sickle cell Anamia: In this disorder erythrocytes destroyed more rapidly then normal leading to anaemia. This occur due to change in 11th autosomal chromosome.
Phenylketonuria: it is an inborn error of metabolism which resulted in mental retardness cause due to change in 12th autosomal chromosomes.
Haemophilia: Gene responsible for this disorder is linked with sex chromosomes.this disease lead to failure of blood clothing.
Colour blindness:This disorder lead to failure to distinguished red & green colour. This gene responsible for this disease is situated on sex chromosome.