BIOL 3333 1st Edition Lecture 11Outline of Last Lecture Dihybrid Mendelian RatiosGene interactionEpistasisComplementary Gene ActionDuplicate Gene Action Dominant EpistasisRecessive epsistasisCurrent LectureTypes of modified phenotypic ratios from Gene Interaction:- comb shape in chickens- flower color in sweet peas- albanism in mammals - fruit color in squash- fruit shape in shepherd’s pursePhenotypic ratio that represents gene interaction of 4 phenotypes:- no gene interaction- 9:3:3:1Phenotypic ratio of gene interaction of complementary gene action:-9:7Phenotypic ratio of gene interaction of recessive suppression - aa on bb:13:7Phenotypic ratio of gene interaction of recessive epistasis - aa acting on B and b:9:3:4Phenotypic ratio of gene interaction of Dominant epistasis of A on B and b:12:3:1Phenotypic ratio of gene interaction of duplicate genes:15:1Continuous variation in populations:- a variation that occurs by adding more genes/alleles to the phenotype - the more interaction, the more possible phenotypic classesMultifactorial inheritance:-shown by continuous traitsWhat is r+ gene?- needed for stimulation of mRNA synthesis of a+ geneSupression at gene product level:These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.First mutation blocks interactionSecond mutation now restores ability for interactionBoth mutations may be required for activity!Testcross situation: independent segregation of dominant alleles in dyhibrid:AaBb x aabb = a 1:1:1:1 ratio of all 4 phenotypesWhat happens to gene loci closely situated on a chromosome:ab and AB will become aB and Ab*If genes are linked closely together on same chromosome - will not show independent assortment Gene configurations that result from closely related genes on same chromosome:A.H Sturtevant;- that crossing over occurs at random during meiosis- and that genes T and U are farther apart than V and WConclusions from this assumption: chromatids cross over between T and U in larger proportion of meioses than between V and W. Measuring gene distances: - count the number of crossovers in given intervalWhat is evidence of linkage?- when ratio is NOT