4. In humans, color vision is X-linked; the gene for color vision is located on the X chromosome but it is absent from the Y chromosome. Normal color vision (XN) is dominant over color blindness (Xn). Suppose a color blind man fathers the children of a woman with the genotype XNXN. a. What genotype is the father? b. What proportion of daughters will be color blind? c. What proportion of sons will be color blind? 5. One daughter from the preceding problem marries a color blind man. a. What proportion of their sons will be color blind? (Another way to think about this is to ask, what are the chances that their sons will be color blind?) b. Explain how a color blind daughter might result from this couple.
Added by Jacob S.
Close
Step 1
The father is color blind, so his genotype must be X"Y, as he has the color blindness gene on his X chromosome and no gene for color vision on his Y chromosome. Show more…
Show all steps
Your feedback will help us improve your experience
Adi S and 73 other Biology educators are ready to help you.
Ask a new question
Labs
Want to see this concept in action?
Explore this concept interactively to see how it behaves as you change inputs.
Key Concepts
Recommended Videos
One form of color blindness (b) in humans is caused by a sex-linked recessive mutant gene. A woman with normal color vision (B) and whose father was color-blind marries a man of normal vision whose father was also color-blind. 1. Give the genotypes of this woman and her husband. 2. What proportion of their total offspring will be color blind? 3. What proportion of males and females will be affected? If a colorblind male is mated with a carrier female: 4. What proportion of the daughters will be affected? 5. In X-linked inheritance, females inherit two copies of the gene while males only inherit one. Explain why this "duplication" of the gene does not result in double the gene product in females. 6. Explain why the carrier female appears to have "normal" vision, while the colorblind male is completely affected by the mutant copy of the allele. Be sure to include an explanation of gene expression in both females and males.
Anand J.
X-Linked Recessive Disorders Color blindness The inability to see red and green colors is called "color blindness". It is caused by the presence of a recessive allele on the X chromosome. Hence, color blindness is known as an X-linked recessive disorder. Because males only carry one copy of the X chromosome, they are more likely to exhibit an X-linked recessive disorder, such as color blindness. Suppose a color blind man marries a homozygous normal woman. What is the probability that this couple will have a color blind child? What is the probability that they will have a daughter who is a carrier for color blindness? Suppose one of their daughters marries a normal man. What is the probability that this couple will have a color blind child? If they have a color blind child, will it be a boy or a girl? Explain: Hemophilia
Bryan V.
Recommended Textbooks
Biology for AP Courses
Objective Biology for NEET
Introduction to General, Organic and Biochemistry
Transcript
18,000,000+
Students on Numerade
Trusted by students at 8,000+ universities
Watch the video solution with this free unlock.
EMAIL
PASSWORD