A series of three-point testcrosses is made to determine the genetic map order of seven linked allele pairs: A/a, B/b, G/g, H/h, Q/q, R/r, and Y/y. From each cross between a triply heterozygous parent listed below, two recombinant classes were noticed as the least frequent among all 8 progeny classes, and are listed at the right in the table. A. For each testcross write the genotype of the F1 heterozygous parent. F1 Parental Phenotype Least frequent F2 Phenotype 1.AHB&ahb AHb & ahB 2.RYh&ryH RYH & ryh 3.BhY&bHy Bhy & bHY 4.qYB&Qyb qYb & QyB 5.AbQ&aBq Abq & aBQ 6.ghR&GHr ghr & GHR
A series of three-point testcrosses is made to determine the genetic map order of seven linked allele pairs: A/a, B/b, G/g, H/h, Q/q, R/r, and Y/y.
From each cross between a triply heterozygous parent listed below, two recombinant classes were noticed as the least frequent among all 8 progeny classes, and are listed at the right in the table.
A. For each testcross write the genotype of the F1 heterozygous parent.
F1 Parental
1.AHB&ahb AHb & ahB
2.RYh&ryH RYH & ryh
3.BhY&bHy Bhy & bHY
4.qYB&Qyb qYb & QyB
5.AbQ&aBq Abq & aBQ
6.ghR&GHr ghr & GHR
B. Write the unified map order of these genes, showing your reasoning.
An allele is a genetic variant, which is expressed as A (capitalized) when the trait is dominant and a (small letters), when the trait is recessive. A homozygous genotype has both alleles as either dominant (AA) or recessive (aa). A heterozygote is a mixed genotype where one allele is dominant and the other is recessive (Aa).
A testcross is a genetic analysis made by crossing a heterozygous parent with a recessive parent. Depending on the number of alleles involved, it is named. Example: A three-point testcross involves a triple heterozygote and a triple recessive phenotype.
The parental generation gives rise to the F1 or first filial generation. The F2 or second generation is obtained by interbreeding of F1.
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