Assignment task: Errors in sex chromosome segregation during meiosis can produce sperm or eggs carrying an abnormal number of sex chromosomes. If one of these gametes is fertilized, this can produce an embryo with an abnormal number of chromosomes, which is usually detected by karyotyping. The most common type of error is nondisjunction, which occurs when sister chromatids or homologous chromosomes fail to separate, and instead migrate together into a daughter cell.
A. Draw a picture of normal meiosis in a male, clearly showing the normal process of separating the X and Y chromosomes into the gametes. (You do not need to illustrate any of the other chromosomes).
B. Draw a picture outlining the expected outcome(s) for the gametes if nondisjunction of the sex chromosomes occurs in a male during meiosis I. Identify the sex chromosome composition and genetic condition (if any) that would result if each of these sperm were to fertilize a normal egg.
C. Draw a picture outlining the expected outcome(s) for the gametes if nondisjunction of the sex chromosomes occurs in a male during meiosis II. Identify the sex chromosome composition and genetic condition (if any) that would result if each of these sperm were to fertilize a normal egg.
D. Klinefelter syndrome is a genetic condition in which a male has a 47,XXY karyotype. In these males, even if meiosis occurs as normally as possible, a high proportion of abnormal sperm may be produced. Explain the difficulty the XXY chromosome composition causes for meiosis, and the possible outcomes for the gametes & offspring