Question

Please answer #19-21, explain and clearly indicate which # you are answering! Thank you in advance!

19. The c-abl gene is normally located on chromosome 9, and the bcr gene on chromosome 22. The abnormal fusion of these two genes resulting from a _______________ event is one of the leading causes of chronic myelogenous leukemia.

A. paracentric inversion

B. pericentric inversion

C. non-reciprocal translocation

D. reciprocal translocation

E. duplication

20. A genetic counselor at a fertility clinic is assessing the condition of a male patient who shows diminished fertility. A sperm count revealed that he is only able to produce about one-third the number of gametes expected of a male with normal fertility. Based on just this information, the genetic counselor suspects that he might be _________________.

A. a translocation homozygote

B. a translocation heterozygote

C. a deletion heterozygote

D. either A or B

E. either B or C

21. While aneuploidy of most autosomes results in lethality in humans, variation in the copy number of the X-chromosome is fairly well tolerated. This is because:

A. the X-chromosome does not harbor many genes.

B. the X-chromosome is not needed for embryonic development.

C. genes on the Y-chromosome can compensate for an abnormal number of X.

D. all X-chromosomes are inactivated.

E. all but one X-chromosome are inactivated.

Answer 1

Ans.19. Chronic mylegenous lukemia is basically caused by reciprocal tranlocation between chromosome 9&22.

Ans.20.deletion heterozygote in which gene for the proper amount of production of sperm that was deleted so abnormal low level found.

Ans 21.all but one x chromosome are inactivated.