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Title: Why can woman be a carrier of a sex-linked trait without expressing that trait in her phenotype? Post by: rixter119 on Feb 26, 2013 Why can woman be a carrier of a sex-linked trait without expressing that trait in her phenotype, while a man cannot? Please help.
Title: Why can woman be a carrier of a sex-linked trait without expressing that trait in her phenotype? Post by: riyadamin on Feb 26, 2013 Sex-linked traits are carried on the X chromosome. A woman has two. If it is a recessive trait, then BOTH X chromosomes must have it for it to be expressed. If only one does, it will not express. A man can carry sex-linked traits without expressing; the thing is, they will be FEMALE sex-linked traits on his X-chromosome. Male sex-linked traits are carried on the Y chromosome, of which there is normally only one, thus there cannot be a recessive male sex-linked trait.
Title: Why can woman be a carrier of a sex-linked trait without expressing that trait in her phenotype? Post by: rixa85 on Feb 26, 2013 Because the remaining X chromosome is enough to make up for the deficient X chromosome. In males, there is no alternate X chromosome to fall back on. Women will express an X linked disorder if both the X chromosomes are faulty, that is, if they inherited faulty X chromosomes from both parents. But this is far less common.
. Title: Why can woman be a carrier of a sex-linked trait without expressing that trait in her phenotype? Post by: tony1653 on Feb 26, 2013 One example of this type of genetics is a disease called Fragile X Syndrome (prominent in Males, extremely rare in females as they must have a father with "FXS" and a mother who is at least a carrier).
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