a haemophilic son is born to a non haemophilic woman and man.using both punnet square and cross diagram,show how this would have occured.
plz help me i do not know if this true.
Answers
Answer:
please see picture for answer
Answer:
The father's sex chromosomes are labeled XY, with the X chromosome carrying the hemophilia gene. [In our drawings, we have shown this by putting an H for hemophilia over the X.] The father only passes half of his sex chromosomes to the baby, either the X or the Y.
If the baby gets the Y chromosome from the father it will be a boy. Since the Y chromosome does not carry the hemophilia gene, a son born to a man with hemophilia and a woman who is not a carrier will not have hemophilia.
If the baby gets the X chromosome from the father it will be a girl. The X chromosome from the father with hemophilia will have the hemophilia gene. But the girl also gets an X chromosome from her mother. The normal blood clotting gene on the X chromosome from the mother is dominant, so the baby girl will not have hemophilia. She will, however, be a hemophilia carrier since she has the hemophilia gene on one of her X chromosomes.
So in this case, all sons born to the couple will be normal and all daughters will be hemophilia carrier
