Essential Cell Biology 5th edition

690 CHAPTER 19 Sexual Reproduction and Genetics
TABLE Q19–17 COMPLEMENTATION ANALYSIS OF Drosophila EYE-COLOR MUTATIONS
Mutation white garnet ruby vermilion cherry coral apricot buff carnation
white – + + + – – – – +
garnet – + + + + + + +
ruby – + + + + + +
vermilion – + + + + +
cherry – – – – +
coral – – – +
apricot – – +
buff – +
carnation –
+ indicates that progeny of a cross between individuals showing the indicated eye colors are phenotypically normal; – indicates that
the eye color of the progeny is abnormal.
number of mutant flies with intermediate eye colors have
been isolated and given names that challenge your color
sense: garnet, ruby, vermilion, cherry, coral, apricot, buff,
and carnation. The mutations responsible for these eyecolor
phenotypes are all recessive. To determine whether
the mutations affected the same or different genes,
homozygous flies for each mutation were bred to one
another in pairs and the eye colors of their progeny were
noted. In Table Q19–17, a + or a – indicates the phenotype
of the progeny flies produced by mating the fly listed at the
top of the column with the fly listed to the left of the row;
brick-red wild-type eyes are shown as + and other colors are
indicated as –.
A. How is it that flies with two different eye colors—ruby
and white, for example—can give rise to progeny that all
have brick-red eyes?
B. Which mutations are alleles of the same gene and which
affect different genes?
C. How can different alleles of the same gene give different
eye colors?
QUESTION 19–18
What are single-nucleotide polymorphisms (SNPs), and
how can they be used to locate a mutant gene by linkage
analysis?