Number of Barr bodies in Klinefelter syndrome is

Question

Question

This question was previously asked in

UP TGT Biology 2011 Official Paper

Answer 1

Concept-

The chromosomal disorders are caused due to absence or excess or abnormal arrangement of one or more chromosomes
The total number of chromosomes in a normal human cell is 46 (23 pairs).
Out of these 22 pairs are autosomes and one pair of chromosomes is a sex chromosome.
Down’s syndrome, Turner’s syndrome, Klinefelter’s syndrome are common examples of chromosomal disorders.

Explanation-

Klinefelter’s syndrome is caused due to the presence of an additional copy of the X-chromosome resulting in a karyotype of 47, XXY.
An inactive X chromosome in the cell which has more than one X chromosome is called a bar body.
Female(XX) have one Barr body.
Male(XY) have no Barr body.

Therefore Klinefelter's syndrome has 47, XXY means 1 Barr body.

Additional Information

Down's syndrome is caused due to the presence of an additional copy of chromosome number 21 (trisomy 21).
Turner's syndrome is caused due to the absence of one of the X chromosomes i.e., 45 with XO.