LIFE 102 Lecture Notes - Down Syndrome, Fundamental Theorem Of Arithmetic, Genetic Linkage
Document Summary
Mapping the distance between genes using recombination data: scientific inquiry. Alfred sturtevant, one of morgan"s students, constructed a genetic map, an ordered list of the genetic loci along a particular chromosome. Sturtevant predicted that the farther apart two genes are, the higher the probability that a crossover will occur between them and therefore the higher the recombination frequency. A linkage map is a genetic map of a chromosome based on recombination frequencies. Distances between genes can be expressed as map units; one map unit, or centimorgan, represents a 5% recombination frequency. Map units indicate relative distance and order, not precise locations of genes. Genes that are far apart on the same chromosome can have a recombination frequency of 50% Such genes are physically linked, but genetically unlinked, and behave as if found on different chromosomes. Sturtevant used recombination frequencies to make linkage maps of fruit fly genes. Using methods like chromosomal banding, geneticists can develop cytogenetic maps of chromosomes.
