Chromosomal Inheritance (College Board AP Biology)

Geneticists investigated the mode of inheritance of a rare disorder that alters glucose metabolism and first shows symptoms in adulthood. The geneticists studied a family in which some individuals of generations II and Ill are known to have the disorder. Based on the pedigree (Figure 1), the geneticists concluded that the disorder arose in individual II—2 and was caused by a mutation in mitochondrial DNA.

Figure 1. Pedigree of a family showing individuals with the glucose metabolism disorder. A question mark indicates that the phenotype is unknown

TABLE 1. AVERAGE BLOOD GLUCOSE LEVELS OF INDIVIDUALS IN GENERATION IV

Individual	Average Blood Glucose Level (mg/dL ± )
IV — 1	170 ± 15
IV — 2	190 ± 10
IV — 3	145 ± 5
IV — 4	165 ± 15
IV — 5	110 ± 15
IV — 6	125 ± 5
IV — 7	105  ± 15
IV — 8	120  ± 10

TABLE 2. PHENOTYPIC CLASSIFICATIONS BASED ON BLOOD GLUCOSE LEVELS

The disorder alters glucose metabolism. Describe the atoms AND types of bonds in a glucose molecule.

Using the template in the space provided for your response, construct an appropriately labeled graph based on the data in Table 1. Determine one individual who is both at risk of developing the disorder and has a significantly different blood glucose level from that of individual IV — 1.

Based on the pedigree, identify all individuals in generation IV who can pass on the mutation to their children.

Based on the fact that individual II — 2 is affected, a student claims that the disorder is inherited in an X-Iinked recessive pattern. Based on the student's claim, predict which individuals of generation Ill will be affected by the disorder. Based on the pedigree, justify why the data do NOT support the student's claim.