By A.K. Matai
Recombination mapping is used to determine if two genes are linked (recombination frequency <50%) or unlinked (recombination frequency ~50%). The distance between two genes is measure in either map units (mu) or centiMorgans (cM).
Recombination Frequency Formula
Sample Recombination Mapping Problem
Gene B for body color (black is completely dominant to yellow) and Gene W for wing shape (straight wings are completely dominant to curved wings) are on the same chromosomes. If true breeding yellow fly is crossed to a true breeding curved wing fly to create heterozygous F1 progeny that is test crossed, the following phenotypic ratios are observed among the F2 progeny.
|black body & straight wings||17|
|yellow body & curved wings||12|
|black body & curved wings||337|
|yellow body & straight wings||364|
Calculate the distance between the two genes.
First, draw out a schematic detailing the all of the crosses. Then, determine which progeny are parents and recombinants.
Insert the numbers into the recombination frequency formula and calculate away!
Questions, Comments or Concerns?
Feel free to post a your questions, comments or concerns down below!
Locke, John; Deyholos, Michael; Harrington, Michael; Canham, Lindsay; Kang, Min, “Open Genetics Lectures (OGL) Fall 2016”
Donar Reiskoffer. Antique map of Leo Belgicus by Visscher C.J. 2011. https://commons.wikimedia.org/wiki/File:Antique_map_of_Leo_Belgicus_by_Visscher_C.J._-_Gerritsz_1630.jpg. Web. 19 Mar. 2017.