If two people with normal vision have a daughter can she be colorblind? I tought that the answer would be no because it is sex linked and the second X in women makes up for the X that is colorblind that she might have but what if they are both carriers of the color blind gene?
Thank you for using the Jiskha Homework Help Forum. Here are some sites on color blindness:
1. http://en.wikipedia.org/wiki/Color_blind
2. http://www.allaboutvision.com/conditions/colordeficiency.htm
3. http://www.agape1.com/color%20vision.htm
Colorblindness is an X-linked gene, a recessive gene on the X chromosome. However, if a man has it, he has no dominant normal color vision gene on the Y chromosome to keep it from being expressed in the phenotype (actual physical traits).
Men cannot be carriers (those who have the trait in their genes but do not express it in their phenotype) for colorblindness. They either lack the colorblind gene or they are colorblind.
A daughter of a carrier mother and a colorblind father can be colorblind. By chance, half of the daughters from this type of union will be colorblind.
I hope this helps a little more. Thanks for asking.
Yes, you are correct that colorblindness is a sex-linked trait and is usually passed down from the mother to the son. In this case, if both parents have normal vision and are carriers of the colorblind gene, there is a possibility that their daughter could be colorblind.
To understand how this could happen, let's look at the genetic makeup of the parents. The mother has two X chromosomes (XX) and is a carrier of the colorblind gene. The father has one X chromosome (X) and one Y chromosome (Y), and he is colorblind.
When the parents have a daughter, she will receive one X chromosome from each of her parents. If she inherits the normal vision gene from her mother's X chromosome, she will have normal vision. However, if she inherits the colorblind gene from her mother's X chromosome, and she does not receive a compensating normal vision gene from her father (since he only has one X chromosome, and it carries the colorblind gene), then she will be colorblind.
It is important to note that if a son is born to these parents, he will definitely be colorblind, as he will receive the colorblind gene from his mother's X chromosome and there is no compensating normal vision gene on the Y chromosome.
I hope this explanation clarifies the scenario for you. If you have any more questions, please feel free to ask.