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Do the genes of the X and Y chromosomes determine only sex characteristics ? / Does the...

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nasirjam | Student, Grade 9 | Honors

Posted December 24, 2012 at 11:07 AM via web

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Do the genes of the X and Y chromosomes determine only sex characteristics ? / Does the sex chromosome contain genes related to sex only ?

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trophyhunter1 | College Teacher | (Level 3) Senior Educator

Posted December 24, 2012 at 2:12 PM (Answer #2)

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The XY chromosome pair determines sex--XX is a female and XY is a male. However, the X chromosome is slightly longer than the Y and contains more genes along its length. Therefore, there are traits known as sex-linked and most of these are found along the X chromosome. An example is red-green colorblindness and another is Hemophilia(bleeder's disease). Since males only have one X chromosome which is passed down from mother to son and if they get an X with the disease gene, then they will express a disease phenotype. Since females have two X chromosomes, if one is normal and the other contains the recessive gene for the disease, they will be carriers and express a normal phenotype. There are also approximately 3 dozen Y-linked genes. These only affect males and relate to male sexual characteristics as well as infertility. These are only passed from father to son.

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