Polygenic Inheritance The simplest model of polygenic inheritance assumes that m
ID: 177715 • Letter: P
Question
Polygenic Inheritance The simplest model of polygenic inheritance assumes that multiple unlinked loci contribute to a trait, and that these loci act in an equal manner. In this tutorial, you will investigate a simple case of polygenic inheritance involving fruit segmentation in orange trees. Part A Examining polygenic inheritance Two pure-breeding lines of orange trees differ in the number of fruit segments they contain: One line produces fruit with 6 segments, and the other produces fruit with 10 segments. When these lines are crossed, the F1 produces fruit with 8 segments. When the F1 trees are crossed, the resulting F2 has nine phenotypic classes of trees. producing fruitwith as few as 4 segments and as many as 12. Pure line 1 Pure line 2 (6 segments) (10 segments) (8 segments) F1 x F1Explanation / Answer
Genotype for 6 segments : A+A+B0B0C0C0D0D0
Genotype for 10 Segments : A0A0B+B+C+C+D+D+
Cross between A+A+B0B0C0C0D0D0 and A0A0B+B+C+C+D+D+ gives F1 as A+A0B+B0C+C0D+D0
A+A0B+B0C+C0D+D0 (Four additive alleles) = 8 segments