Question

22. [9 PTS] Turner syndrome results when an individual has a genotype of XO (a single X chromosome), and no other sex chromosomes. Color-blindness results from mutation of a single gene on the X chromosome. A couple, both of whom have normal color vision, have a color-blind child with Turner's syndrome. a. Did non-disjunction occur in the mother, or the father, or is it impossible to tell? Explain your answer. (3 pts) (continued next page. b. In the space provided below: (6 pts) • • Draw meiosis in both parents. You MUST include: the beginning cells, anaphase I and II and the final cells. Showing only the sex chromosomes. Illustrate how the meiotic nondisjunction event occurred. If you think it could happen in either meiosis I or II, pick one of these for illustration. Label the ploidy (2n or n) of ALL the cells. Label ALL chromatids in each cell. •

Answer 1

1. An individual suffering from turner's syndrome is always a female. And it is given that it is also having colour blindness. And both the parents are normal. So the mother parent will be the career of colour blind gene so that this affected chromosome is passed on to the doctor.

The nondisjunction of chromosome will occur during meiosis 1 during the formation of gametes in father. This is because the daughter will receive the X chromosome carrying the mutated colorblind green from the mother so she will get no gamete from the father.

2.

Of (Mother) Oy (father) хү osis-1 ronde newsis 2 px Turner colour blind

Please rate high.