Genetic Linkage
Genetics
Experimental Analysis
Set #2
Linkage
1. In gorgonzolas, there are three recessive traits that affect the organism’s appeal: shrunken fruit, foul-smelling flowers, and short height. A heterozygote was crossed with a homozygote, yielding the following offspring: 46 - foul-smelling 44 - shrunken fruit, short height 8 - short height 8 - shrunken fruit 7 - foul-smelling, short height 6 - foul-smelling, shrunken fruit 3 - foul-smelling, shrunken fruit, short height 1 - normal phenotype
Determine the genetic map for these traits, showing map distances.
2. Given the following three genes: Q -10 mu - P -30 mu - S
You cross a homozygous dominant individual with a homozygous recessive individual, and obtain an F1 generation. You then cross an F1 individual in a testcross. What will the F2 progeny genotypes be? In total of 2000 progeny, how many offspring will be present in each genotypic class?
3. An individual heterozygous for 4 genes ABCD was testcrossed, and the progeny were classified by the gametic contribution of the heterozygous parent as follows:
a B C D 42 A b c d 43 A B C d 140 a b c D 145 a B c D 6 A b C d 9 A B c d 305 a b C D 310
Which genes are linked? Show quantitative data to support your decisions.
Draw a map of the linked genes, showing the order of the genes and the distances in map units between the genes.
4. The R and S loci are 35 mu apart. If a plant of the genotype
R S r s
is selfed, what progeny phenotypes will be seen and in what proportions?
5. The allele b gives Drosophila flies a black body and b+ gives brown, the wild-type phenotype. The allele wx of a separate gene gives waxy wings and wx+ gives nonwaxy, the wild-type phenotype. The allele cn of a third gene gives cinnabar eyes and cn+ gives red, the wild-type phenotype. A female heterozygous for these three genes is testcrossed, and 1000
Experimental Analysis
Set #2
Linkage
1. In gorgonzolas, there are three recessive traits that affect the organism’s appeal: shrunken fruit, foul-smelling flowers, and short height. A heterozygote was crossed with a homozygote, yielding the following offspring: 46 - foul-smelling 44 - shrunken fruit, short height 8 - short height 8 - shrunken fruit 7 - foul-smelling, short height 6 - foul-smelling, shrunken fruit 3 - foul-smelling, shrunken fruit, short height 1 - normal phenotype
Determine the genetic map for these traits, showing map distances.
2. Given the following three genes: Q -10 mu - P -30 mu - S
You cross a homozygous dominant individual with a homozygous recessive individual, and obtain an F1 generation. You then cross an F1 individual in a testcross. What will the F2 progeny genotypes be? In total of 2000 progeny, how many offspring will be present in each genotypic class?
3. An individual heterozygous for 4 genes ABCD was testcrossed, and the progeny were classified by the gametic contribution of the heterozygous parent as follows:
a B C D 42 A b c d 43 A B C d 140 a b c D 145 a B c D 6 A b C d 9 A B c d 305 a b C D 310
Which genes are linked? Show quantitative data to support your decisions.
Draw a map of the linked genes, showing the order of the genes and the distances in map units between the genes.
4. The R and S loci are 35 mu apart. If a plant of the genotype
R S r s
is selfed, what progeny phenotypes will be seen and in what proportions?
5. The allele b gives Drosophila flies a black body and b+ gives brown, the wild-type phenotype. The allele wx of a separate gene gives waxy wings and wx+ gives nonwaxy, the wild-type phenotype. The allele cn of a third gene gives cinnabar eyes and cn+ gives red, the wild-type phenotype. A female heterozygous for these three genes is testcrossed, and 1000