How Gene Mapping Works

Any particular gene has a specific location (its “locus“) on a particular chromosome. For any two genes (or loci) alpha and beta, we can ask “What is the recombination frequency between them?“ If the genes are on different chromosomes, the answer is 50% (independent assortment). If the two genes are on the same chromosome, the recombination frequency will be somewhere in the range from 0 to 50%. The “map unit“ (1 cM) is the genetic map distance that corresponds to a recombination frequency of 1%. In large chromosomes, the cumulative map distance may be much greater than 50cM, but the maximum recombination frequency is 50%. Why? In large chromosomes, there is enough length to allow for multiple cross-overs, so we have to ask what result we expect for random multiple cross-overs. Problem: A scientist performs a series of experiments to determine the recombination frequencies between the following genes. He acquires the following data: W-X: 3% X-Y: 2% Y-Z: 13% Z-W: 8% Which of the following choices places the genes in the correct order relative to one another? A) X, W, Z, Y B) W, Y, Z, X C) Z, W, X, Y D) W, X, Y, Z #educationalVideos #scienceVideos #highSchoolScience #GeneticRecombinationAwardWinningWork #GeneMappingLiteratureSubject #EducationWord #Genetics #Genes #apBiology #NikolaysGeneticsLessons #geneMapping #Recombination #crossingOver #DrosophilaEyeColor #percentRecombination #recombinationFrequency #mapUnits #recombinationUnitsExample #recombinationFrequencyExample #determiningRecombinationgFrequency #geneticRecombination