Philadelphia Syndrome occurs when the distal segments of chromosome 9 and chromosome 22 are reciprocally translocated. Examine the diagram below. Chromosome 9 is on the left while chromosome 22 is on the right. The areas bounded by the dashed lines are the portions of the chromosomes that are translocated. The labeled black bands on the chromosomes are genes. Note the position of the ABL1 gene on chromosome 9 and the BCR gene and PDGFB gene on chromosome 22.

a. How does the translocation affect the location of the labeled genes? Where does the ABL1 gene end up? Where does the PDGFB gene end up? Draw what the chromosomes would look like after the translocation. Show the correct positions of the ABL1 gene, the BCR gene, and the PDGFB gene. Use the space to the right of the illustration. (2)

b. Philadelphia syndrome results when a hybrid gene is created by the translocation described above. This hybrid gene codes for a signaling protein that causes the cell to divide uncontrollably. Based on what you know about cell cycle control, speculate on how this signaling protein might be responsible for uncontrolled cell division. (3)