. For several years, Hans Nachtsheim investigated an inherited anomaly of the white blood cells of rabbits. Thisanomaly, termed the Pelger anomaly, is the arrest ofthe segmentation of the nuclei of certain white cells. Thisanomaly does not appear to seriously burden the rabbits.a. When rabbits showing the Pelger anomaly were matedwith rabbits from a true-breeding normal stock,Nachtsheim counted 217 offspring showing the Pelgeranomaly and 237 normal progeny. What is the geneticbasis of the Pelger anomaly?b. When rabbits with the Pelger anomaly were matedwith each other, Nachtsheim found 223 normal progeny,439 with the Pelger anomaly, and 39 extremely abnormalprogeny. These very abnormal progeny not only haddefective white blood cells, but also showed severedeformities of the skeletal system; almost all of themdied soon after birth. In genetic terms, what do yousuppose these extremely defective rabbits represented?Why were there only 39 of them?c. What additional experimental evidence might youcollect to test your hypothesis in part b?d. In Berlin, about 1 human in 1000 shows a Pelgeranomaly of white blood cells very similar to thatdescribed for rabbits. The anomaly is inherited as asimple dominant, but the homozygous type has not beenobserved in humans. Based on the condition in rabbits,why do you suppose the human homozygous has notbeen observed?e. Again by analogy with rabbits, what phenotypes andgenotypes would you expect among the children of aman and woman who both show the Pelger anomaly?(Data from A. M. Srb, R. D. Owen, and R. S. Edgar,General Genetics, 2nd ed. W. H. Freeman and Company,1965.)
. For several years, Hans Nachtsheim investigated an inherited anomaly of the white blood cells of rabbits. This
anomaly, termed the Pelger anomaly, is the arrest of
the segmentation of the nuclei of certain white cells. This
anomaly does not appear to seriously burden the rabbits.
a. When rabbits showing the Pelger anomaly were mated
with rabbits from a true-breeding normal stock,
Nachtsheim counted 217 offspring showing the Pelger
anomaly and 237 normal progeny. What is the genetic
basis of the Pelger anomaly?
b. When rabbits with the Pelger anomaly were mated
with each other, Nachtsheim found 223 normal progeny,
439 with the Pelger anomaly, and 39 extremely abnormal
progeny. These very abnormal progeny not only had
defective white blood cells, but also showed severe
deformities of the skeletal system; almost all of them
died soon after birth. In genetic terms, what do you
suppose these extremely defective rabbits represented?
Why were there only 39 of them?
c. What additional experimental evidence might you
collect to test your hypothesis in part b?
d. In Berlin, about 1 human in 1000 shows a Pelger
anomaly of white blood cells very similar to that
described for rabbits. The anomaly is inherited as a
simple dominant, but the homozygous type has not been
observed in humans. Based on the condition in rabbits,
why do you suppose the human homozygous has not
been observed?
e. Again by analogy with rabbits, what
genotypes would you expect among the children of a
man and woman who both show the Pelger anomaly?
(Data from A. M. Srb, R. D. Owen, and R. S. Edgar,
General Genetics, 2nd ed. W. H. Freeman and Company,
1965.)
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