A corn geneticist wants to obtain a corn plant that hasthe three dominant phenotypes: anthocyanin (A), longtassels (L), and dwarf plant (D). In her collection ofpure lines, the only lines that bear these alleles are AALL dd and aa ll DD. She also has the fully recessive lineaa ll dd. She decides to intercross the first two and testcross the resulting hybrid to obtain in the progeny aplant of the desired phenotype (which would have to beAa Ll Dd in this case). She knows that the three genesare linked in the order written, that the distance between the A/a and the L/l loci is 16 m.u., and that thedistance between the L/l and the D/d loci is 24 m.u.a. Draw a diagram of the chromosomes of the parents,the hybrid, and the tester.b. Draw a diagram of the crossover(s) necessary toproduce the desired genotype.c. What percentage of the testcross progeny will be ofthe phenotype that she needs?d. What assumptions did you make (if any)?
A corn geneticist wants to obtain a corn plant that has
the three dominant
tassels (L), and dwarf plant (D). In her collection of
pure lines, the only lines that bear these alleles are AA
LL dd and aa ll DD. She also has the fully recessive line
aa ll dd. She decides to intercross the first two and testcross the resulting hybrid to obtain in the progeny a
plant of the desired phenotype (which would have to be
Aa Ll Dd in this case). She knows that the three genes
are linked in the order written, that the distance between the A/a and the L/l loci is 16 m.u., and that the
distance between the L/l and the D/d loci is 24 m.u.
a. Draw a diagram of the chromosomes of the parents,
the hybrid, and the tester.
b. Draw a diagram of the crossover(s) necessary to
produce the desired genotype.
c. What percentage of the testcross progeny will be of
the phenotype that she needs?
d. What assumptions did you make (if any)?
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