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(No partial credit) The gene for nose shape is found on the X chromosome

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(No partial credit) The gene for nose shape is found on the X chromosome. Round nose is dominant to pointed nose.

Human individuals with XXY (an additional X chromosome) are male. Individuals with XO (only one X chromosome) are female. Individuals with XXX (three X chromosomes) are female.

For each of the following families, identify the possible nondisjunction events (Very rare  mistakes during meiosis) that could explain the phenotype of the child. Circle one answer for each parent. (Select “neither” if nondisjunction in that parent could not produce the child’s phenotypic outcome. For example, if you think nondisjunction only in the father could explain the child’s phenotype, then circle “neither” for the mother).

1. A man with a round nose and a woman with a round nose have a daughter with a pointed nose. This daughter has Turner Syndrome (genotype XO; one X chromosome).

2. A man with a round nose and a woman with a round nose have a son with Klinefelter Syndrome (genotype XXY) with a pointed nose.

3. A man with a round nose and a woman with a pointed nose have a son with Klinefelter Syndrome (genotype XXY) with a pointed nose.

4. A man with a pointed nose and a woman with a round nose have a daughter with a pointed nose. The genotype of this daughter is XXX (metafemale).