BRAINCAKEChromosome Mapping
The further apart two genes are on a chromosome, the more likely it is that a chiasma forms between them and separates their alleles. So the recombination frequency between two linked genes can be used as a measure of the distance between them. This allows the relative positions of genes to be worked out, called chromosome mapping (or linkage mapping).
The idea was first used by Alfred Sturtevant, a student of Morgan, with Drosophila in 1913. Distances are given in map units:
1% recombination frequency = 1 map unit (1 centimorgan)
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Key terms in this lesson
- recombination frequency
- The proportion of offspring from a test cross showing a new combination of alleles produced by crossing over, used as a measure of gene distance.
More in Genetic Information
- Chi-Squared Test - Monohybrid Crosses
- Chi-Squared Test- Dihybrid Crosses
- Gene Linkage
- Identifying Linked Genes
- Sex-Linkage
- Pedigree Diagrams
- The Albino Trait
- Sex-Linked Diseases
All 30 lessons in Genetic Information · All Edexcel A-level Biology topics