Indicate the expected number of Ban bodies in interphase cel

Indicate the expected number of Ban bodies in interphase cells of individuals with the following karyotypes. Part A 46 XY 21 Part B 45 XO (Turner\'s syndrome) _____

Solution

Barr body is an inactive form of X chromosome present in the somatic cells.

The X chromosome inactivationor lyonization occurs in those species in which the sex determination occurs by the presence of Y chromosome.

According to Lyon hypothesis if a female somatic cells contain n number of X chromosome during embryogenesis then total n-1 number of chromosomes are inactivation, eg if there are 4 X chromosomes during embryogenesis them 3 will be inactivated and only one will be left functional. In humans extra Barr bodies are visible at the interphase phase of cell division.

Normal male with karyotype- 46,XY has no Barr body

Normal female with a karyotype-46,XX has one Barr body

In Turner syndrome- 45,XO- female having no Barr body

In kleinfelter syndrome-47,XXY- presence of one Barr body

In trisomy- 47,XXX- there is presence to 2 Barr bodies.