131k views
1 vote
Juan and julia have one son and one daughter. their son is color-blind, but their daughter is not. this can be explained by the fact that:

2 Answers

2 votes

Answer:

X-linked recessive genes almost never have a counterpart on the Y chromosome.

Step-by-step explanation:

Psych 200

User Tim Habersack
by
8.5k points
3 votes
Color-blindness is caused by a defective gene carried on the X chromosome. The counterpart to the X chromosome -- the Y chromosome -- does not contain a gene for color vision at all. A son always gets an X chromosome from his mother and a Y chromosome from his father; if the X chromosome has the defective color-vision gene, there will be no functioning gene on his Y chromosome to oppose it. A daughter gets an X chromosome from her mother and another from her father. In this example, although the girl inherited the same defective color-vision gene from her mother as her brother did, the X chromosome from her father contained a fully functional gene that was sufficient to produce normal color vision. So, the mother, in this case, carried the gene for color-blindness but the father did not.
User Anemoia
by
8.7k points

No related questions found

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.