A--What do you get if you add the number of maternal chromosomes in a somatic cell to the number of autosomes in a sex cell, then subtract the number of Barr bodies in a somatic cell of a person with kleinfelter's syndrome?

Question

Scarlet Owens

Biology

17 March, 13:54

A--What do you get if you add the number of maternal chromosomes in a somatic cell to the number of autosomes in a sex cell, then subtract the number of Barr bodies in a somatic cell of a person with kleinfelter's syndrome?

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Answers (1)

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Grant Peck · Answer 1

44

Explanation:

A somatic cell is diploid - it has 46 chromosomes. Half of these are from the mother, so there are 23 maternal chromosomes

A sex cell (gamete) is haploid - it has 23 chromosomes. There are (usually) two sex chromosomes in a diploid genome, either XX or XY, so there is one 1 in a haploid cell, giving a total of 22 autosomes

Barr bodies are inactive X chromosomes in a female somatic cell. This occurs to control dosage compensation (otherwise all the genes on the X in females would be expressed twice as much as they are in males). In a healthy female, there is normally one Barr body

A person with Kleinfelter's syndrome has two X chromosomes and one Y (XXY). They are biologically male, but have two X chromosomes. Therefore, one of these becomes a Barr body, as in females.

23 + 22 - 1 = 44