2006-12-10 16:19:23 · 4 answers · asked by hellokid 1 in Science & Mathematics ➔ Biology
Barr bodies are inactivated X chromosomes. They are only found in females because females have two X chromosome, while males only have one, and females need to inactive one of their two so that they only receive one "dose" of genes from the X chromosomes. In inactivating one of their two X chromosomes, females receive the same "dose" of X chromosome genes as males, which is desirable.
Every cell in a female has a full set of chromosomes, which means that each cell must inactivate one of the X chromosomes. So, theoretically, the number of barr bodies in a female will equal the total number of all cells in a female.
2006-12-10 18:32:00 · answer #1 · answered by Anonymous · 1⤊ 0⤋
Like others have said Barr bodies are mostly inactive X chromosomes. But they are not only found in females. It is possible for males or females to have more than one X, several even, because malesness is determined by Y, not number of Xs.
The # of Barr bodies = # of X chromosomes - 1.
This is because of dosage compensation. Typically, males have one X and females have two. So to adjust for this the cell inactivates one of the X chromosomes in the female cell, so both males and females are only expressing one X. Which X that is inactivated is random and differs from each cell. This can be seen in the different color patchs on the coat of calico cats.
2006-12-11 10:40:57 · answer #2 · answered by niki jean 2 · 0⤊ 0⤋
A barr body is an inactive X chromosome, observable in an interphase cell. I don't know how to predict how many a person may have.
2006-12-11 00:25:07 · answer #3 · answered by Maynard J Stinkfist 2 · 0⤊ 1⤋
Barr bodies are inactive X chromosomes. Females have two X chromosomes, but you don't need both to be active at the same time in each cell. Only one X in each cell is active.
Unless you have more than two X chromosomes (triple-X), you will only have one Barr body in each cell.
2006-12-11 00:25:36 · answer #4 · answered by jar 3 · 1⤊ 1⤋