Question

There is a simple formula for determining the number of Barr bodies in a given cell: N - 1, where N is the number of X chromosomes. How many Barr bodies are present in each of the following conditions?

1) Kleinfelter syndrome (XXY) = 1
2) Turner syndrome (XO) = 0
3) 47 XYY = 0
4) 47 XXX = 2
5) 48 XXXX = 3

Answer 1

The number of Barr bodies, which represent inactivated X chromosomes, is determined by subtracting one from the total number of X chromosomes (N - 1). According to this formula, Klinefelter syndrome has 1 Barr body, Turner syndrome has 0, 47, XYY has 0, 47, XXX has 2, and 48, XXXX has 3. Option number 3 is correct.

Step-by-step explanation:

The number of Barr bodies in a cell is determined by the formula N - 1, where N is the number of X chromosomes. Here's how it applies to various conditions:

• Kleinfelter syndrome (XXY) has 1 Barr body.
• Turner syndrome (XO) has 0 Barr bodies since there's only one X chromosome.
• 47, XYY has 0 Barr bodies because the presence of the Y chromosome does not impact the number of X chromosomes, which is one.
• 47, XXX (Triple X syndrome) results in 2 Barr bodies.
• 48, XXXX has 3 Barr bodies since there are four X chromosomes.

Barr bodies are inactivated X chromosomes that compensate for the excess genetic dosage in conditions where there are more than one X chromosome present in the genetic makeup.