Page 96 - Genetics_From_Genes_to_Genomes_6th_FULL_Part1

88 Chapter 3 Extensions to Mendel’s Laws

c. If this trait is instead quite common in the
population, what alternative explanation would
you propose for the inheritance?
d. Based on this new explanation in (c), which non-
expressing members of these families must have
the genotype normally causing the trait?

The Smiths

I
1 2
II
1 2 3 4
III © McGraw-Hill Education/Gary He
1 2 3 4 5 6 7
IV
1 2 3 4
The Je ersons
I
1 2
II
1 2 3 4 5 6 7
III
1 2 3 4 5 6

50. Polycystic kidney disease is a dominant trait that
causes the growth of numerous cysts in the kidneys. © The Print Collector/Getty Images
The condition eventually leads to kidney failure. A 52. Using each of the seven coat color genes discussed
child with polycystic kidney disease is born to a in the text (listed in Table 3.3), propose a possible
couple, neither of whom shows the disease. What genotype for each of the three Labrador retrievers in
possibilities might explain this outcome? Fig. 3.12a. Keep in mind that the Labrador retrievers
51. Identical (monozygotic) twins have similar, but not are pure-breeding for uniformly colored coats without
identical, fingerprints. Given that all the alleles of all spots or eye masks. Explain any ambiguities in your
the genes of identical twins are the same, explain how genotype assignments.
this outcome is possible.