Homework SourseThe pedigree below shows the inheritance of redgreen colorbl
The pedigree below shows the inheritance of red-green colorblindness, an X-linked recessive trait (XD = normal vision, Xd = colorblindness allele). For all of the questions below, assume that there is no abnormal event or new mutation; also, ignore X-inactivation for this problem. Below each individual (except III-1), write out their genotype for color vision. Use \"?\" to indicate any allele about which you are uncertain. What is the probability that III-1 will be colorblind? Explain your reasoning to show how you arrived at you answer. Using long and short chromosomes for the X and Y, respectively, diagram the sex chromosomes as they would appear in a proper metaphase I of meiosis in individual II-3 of the pedigree above. Be sure to mark the colorvision locus where you think it could be located.
Solution
XDXd (carrier female) (1/4)
| XD (1/2) | Xd (1/2) | |
| XD (1/2) | XDXD (normal female) (1/4) | XDXd (carrier female) (1/4) |
| y (1/2) | XDy (normal male) (1/4) | Xdy (colourblindness male) (1/4) |
