genetic map The linear arrangement of mutable sites on a chromosome, deduced from genetic recombination experiments. The percentage of recombinants is used as a quantitative index of the distance between two gene pairs, and this distance, together with those between other gene pairs, provides a map of their arrangement on the chromosome. One ‘genetic map unit’ is defined as the distance between gene pairs for which one product of meiosis out of a hundred is recombinant (i.e. it equals a recombination frequency of 1 per cent).

genetic map The linear arrangement of mutable sites on a chromosome, deduced from genetic-recombination experiments. The percentage of recombinants is used as a quantitative index of the distance between two gene pairs, and this distance, together with those between other gene pairs, provide a map of their arrangement on the chromosome. One ‘genetic map unit’ is defined as the distance between gene pairs for which one product of meiosis out of one hundred is recombinant (i.e. it equals a recombination frequency of 1%).