Question

What is Philadelphia chromosome?
A. A chromosome common between a gorilla and a man
B. An abnormal chromosome found in the patients of certain blood cancers
C. An extra chromosome found in the residents of Philadelphia
D. A hypothetical chromosome thought to have been present in the neanderthal man

Answer 1

The Philadelphia chromosome forms when chromosomal segments break and exchange portions. This creates an abnormally small chromosome 22. David A. Hungerford, Peter C. Nowell together found the Philadelphia chromosome in 1959 within chronic myelogenous leukaemia (CML). The chromosomal defect that can be seen in this chromosome is a reciprocal translocation.

Complete answer:
Philadelphia is an abnormal chromosome formed from the exchange of a small portion of chromosome 9 and chromosome 22. By this process, an abnormal chromosome 22 is formed. A new combination of instructions from proteins for cells leads to the development of chronic myelogenous leukemia (CML). There is no common chromosome between human and gorilla. In humans, chromosome 2 is a fusion of chromosome 2a and 2b of gorilla and chimpanzees. Though there are many similar genes and similar chromosomal content between gorilla and human, but not exactly common chromosomes. There is no extra chromosome found in residents of Philadelphia. Therefore, there is no hypothetical chromosome in the neanderthal man. The Y chromosome was evolved from the Neanderthal man.
Hence, the correct answer is option C.

Note: CML is a type of blood cancer. It causes an increased number of white blood cells in the blood. It can also be called chronic myeloid leukemia and chronic granulocytic leukemia because it affects older adults and rarely occurs in children, though it can occur at any age. Philadelphia is a good example of translocation that involves the fusion of a proto-oncogene called c-ABL.