4. Genetic Mapping and Linkage

Trihybrid Cross

Multiple Choice
The following table shows data from a cross (ABC x abc) examining three genes (a, b, and c). Calculate the recombination frequency for A and B
Multiple Choice
The following table shows data from a cross examining three genes (a, b, and c). Calculate the recombination frequency for A and C
Multiple Choice
The following table shows data from a cross examining three genes (a, b, and c). Determine the order of genes
Open Question
Determine whether the statements below are true or false. If a statement is false, provide the correct information or revise the statement to make it correct.The outcome of a trihybrid cross is predicted by the law of segregation.
Open Question
Determine whether the statements below are true or false. If a statement is false, provide the correct information or revise the statement to make it correct.

The progeny of a trihybrid cross are expected to have one of 27 different genotypes.
Open Question
Three gene pairs located on separate autosomes determine flower color and shape as well as plant height. The first pair exhibits incomplete dominance, where the color can be red, pink (the heterozygote), or white. The second pair leads to personate (dominant) or peloric (recessive) flower shape, while the third gene pair produces either the dominant tall trait or the recessive dwarf trait. Homozygous plants that are red, personate, and tall are crossed to those that are white, peloric, and dwarf. Determine the F₁ genotype(s) and phenotype(s). If the F₁ plants are interbred, what proportion of the offspring will exhibit the same phenotype as the F₁ plants?
Open Question
Researchers cross a corn plant that is pure-breeding for the dominant traits colored aleurone (C1), full kernel (Sh), and waxy endosperm (Wx) to a pure-breeding plant with the recessive traits colorless aleurone (c1), shrunken kernel (sh), and starchy (wx). The resulting F₁ plants were crossed to pure-breeding colorless, shrunken, starchy plants. Counting the kernels from about 30 ears of corn yields the following data.Kernel Phenotype NumberColored, shrunken, starchy 116Colored, full, waxy 601Colored, full, starchy 2538Colored, shrunken, waxy 4Colorless, shrunken, starchy 2708Colorless, full, starchy 2Colorless, full, waxy 113Colorless, shrunken, waxy 6266708What is the interference value for this data set?
Open Question
Researchers cross a corn plant that is pure-breeding for the dominant traits colored aleurone (C1), full kernel (Sh), and waxy endosperm (Wx) to a pure-breeding plant with the recessive traits colorless aleurone (c1), shrunken kernel (sh), and starchy (wx). The resulting F₁ plants were crossed to pure-breeding colorless, shrunken, starchy plants. Counting the kernels from about 30 ears of corn yields the following data.

Kernel Phenotype Number
Colored, shrunken, starchy 116
Colored, full, waxy 601
Colored, full, starchy 2538
Colored, shrunken, waxy 4
Colorless, shrunken, starchy 2708
Colorless, full, starchy 2
Colorless, full, waxy 113
Colorless, shrunken, waxy 626
6708

Calculate the recombination frequencies between the gene pairs.
Open Question
As in Problem 12, flower color may be red, white, or pink, and flower shape may be personate or peloric. For the following crosses, determine the P₁ and F₁ genotypes:
Open Question
In a diploid plant species, an F₁ with the genotype Gg Ll Tt is test-crossed to a pure-breeding recessive plant with the genotype gg ll tt. The offspring genotypes are as follows:Genotype NumberGg Ll Tt 621Gg Ll tt 3Gg ll Tt 64Gg ll tt 109gg Ll Tt 103gg Ll tt 67gg ll Tt 7gg ll tt 6261600Calculate the recombination frequency between each pair of genes.
Open Question
In a diploid plant species, an F₁ with the genotype Gg Ll Tt is test-crossed to a pure-breeding recessive plant with the genotype gg ll tt. The offspring genotypes are as follows:Genotype NumberGg Ll Tt 621Gg Ll tt 3Gg ll Tt 64Gg ll tt 109gg Ll Tt 103gg Ll tt 67gg ll Tt 7gg ll tt 6261600What is the order of these three linked genes?
Open Question
In Drosophila, Dichaete (D) is a mutation on chromosome III with a dominant effect on wing shape. It is lethal when homozygous. The genes ebony body (e) and pink eye (p) are recessive mutations on chromosome III. Flies from a Dichaete stock were crossed to homozygous ebony, pink flies, and the F₁ progeny, with a Dichaete phenotype, were backcrossed to the ebony, pink homozygotes. Using the results of this backcross shown in the table,Phenotype NumberDichaete 401ebony, pink 389Dichaete, ebony 84pink 96Dichaete, pink 2ebony 3Dichaete, ebony, pink 12wild type 13Diagram this cross, showing the genotypes of the parents and offspring of both crosses.
Open Question
An organism of the genotype AaBbCc was testcrossed to a triply recessive organism (aabbcc). The genotypes of the progeny are presented in the following table.20 AaBbCc 20 AaBbcc20 aabbCc 20 aabbcc5 AabbCc 5 Aabbcc5 aaBbCc 5 aaBbccWhat can you conclude from the actual data about the location of the three genes in relation to one another?
Open Question
An organism of the genotype AaBbCc was testcrossed to a triply recessive organism (aabbcc). The genotypes of the progeny are presented in the following table.20 AaBbCc 20 AaBbcc20 aabbCc 20 aabbcc5 AabbCc 5 Aabbcc5 aaBbCc 5 aaBbccAnswer part (a) again, assuming the three genes are so tightly linked on a single chromosome that no crossover gametes were recovered in the sample of offspring.
Open Question
An organism of the genotype AaBbCc was testcrossed to a triply recessive organism (aabbcc). The genotypes of the progeny are presented in the following table.20 AaBbCc 20 AaBbcc20 aabbCc 20 aabbcc5 AabbCc 5 Aabbcc5 aaBbCc 5 aaBbccIf these three genes were all assorting independently, how many genotypic and phenotypic classes would result in the offspring, and in what proportion, assuming simple dominance and recessiveness in each gene pair?