When fertilization takes place, the sperm fertilizes the egg.
Now, sperms are of two types: Haploid-Y or Haploid-X,
whereas the egg is of just one type: Haploid-X.
So the resulting child may be Diploid-XY (Boy) or Diploid-XX (Girl).
However, in girls, the double dose of X chromosomes isn't really necessary, and one of the X chromosome is rendered inactive, by a process called Lyonization.
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Barr BodiesMurray Barr discovered these inactive X Chromosome in a female somatic cell and named them Barr Bodies. They are sometimes referred to as sex chromatin.
The number of Barr bodies is one less than the number of X chromosomes.
Recessive Sex-Linked Genetics DisordersThe anomalies with genes found on X Chromosomes can lead to diseases like hemophilia, autism, Muscular dystrophy (Duchenne's pseudohypertrophy and Becker's benign pseudohypertrophic dystrophy, which is less severe), G-6-PD Deficiency syndrome, Color Blindness and Night Blindness.
Multiple Choice Questions
Which of the following statement is true? (1) Length of X is more than that of Y (2) X chromosomes is the sex determiner (3) Length of X is equal to that of Y (4) X chromosomes has Holandric genes Ans: http://zoomgenetics.apphb.com/?id=m228
In female mammals the two X chromosomes are (1) both active (2) both inactive (silenced) (3) one silenced (4) both are partially active Ans: http://zoomgenetics.apphb.com/?id=m234
Number of barr bodies in Super males? (1) 0 (2) 1 (3) 2 (4) 3 Ans: http://zoomgenetics.apphb.com/?id=m270
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