Question

In the cell of super female with 47 chromosome (44 + XXX) visible barr bodies are
A. 1
B. 0
C. 2
D. 3

Answer 1

Hint: The number of visible Barr bodies can be counted easily and determined as it is always present one lesser in number than the total number of X chromosomes that is subtract one from the total number of X chromosomes.

Complete Answer:
- A Barr body is defined as an inactive X chromosome that is a female chromosome present in a cell where the X chromosomes are more than one. The number of Barr bodies in humans is always found to be one lesser than the tidal and total number of X chromosomes which is visible at the interphase and when the X chromosome present is more than one. A Barr body is named after it has been discovered by Murray Barr.
- Barr body is an inactive form of chromosome in a process called lyonization, during XY sex determination.
- According to the Lyon hypothesis, the cells with multiple X chromosomes will have one inactivated X chromosome during the process of mammalian embryogenesis. this process is known as inactivation of x chromosome
- This anomaly occurs during the early stage of embryogenesis. It occurs in almost all the mammals except some placental mammals where the X chromosome of the sperm is generally inactivated.
- If a person is suffering from Klinefelter syndrome having 47+XXY chromosomes then Barr's body will be one less than the X chromosome which will be one. If a person is having a karyotype 47+XXX chromosomes, then the Barr bodies present will be two.
- Klinefelter’s Syndrome occurs due to the presence of an additional and an extra copy of X-chromosome resulting into 44 + XXY type chromosome complement. The defect appears due to union of an abnormal egg (22+ XX) and a normal sperm (22 + Y) or normal egg (22 + X) and abnormal sperm (22 + XY).
- Such persons are sterile males that are the males that lack capacity to reproduce with overall masculine development and some female characteristics (e.g Feminine pitched voice, development of breast or gynaecomastia).

So, the correct answer is C that is 2.

Note: A person who is possessing two X chromosomes as in the case of human females has only one Barr body while the person with one X chromosome as that of the presence of human males will have no Barr body. Barr bodies can be observed in the nucleus of the neutrophils, at the corner of the nucleus in female somatic cells between divisions. The Barr body is responsible for femaleness (that is observance of female like characteristics) genetically.