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By finding recombination frequencies for many gene pairs, we can make linkage maps that show the order and relative distances of the genes on the chromosome.
16 gru 2021 · A crossover frequency between 0 percent and 50 percent indicates that the genes are on the same chromosome and crossover occurs some of the time. Figure \(\PageIndex{1}\): Genetic Maps: This genetic map orders Drosophila genes on the basis of recombination frequency.
A comparison of nonrecombination (left) with recombination (right), shows how recombination affects the way chromosomes are passed into gametes in Meiosis II. On the right, a single crossover...
For example, take a look the meiosis II diagram above, which shows the products of meiosis for a cell with 2 n = 4 chromosomes. Each gamete has a unique "sample" of the genetic material present in the starting cell.
Learn how the distance between genes on a chromosome influences their likelihood to recombine. Dive into the concept of centimorgans, the unit of measurement for gene distance, and how it relates to the frequency of recombination.
Gene Linkage Maps: Using the crossover frequencies, you can construct a map to represent the distances between genes. This map shows chromosome #2 of Drosophila melanogaster . The distance between the genes can be written as a percentage or as a MAP UNIT.
Calculating the map distance of the whole chromosome (end-to-end) of over 50cM comes from mapping of multiple loci dispersed along the chromosome, each with a value of less than 50%, with their total adding up to the value over 50cM (e.g. >100 cM as above). The method for mapping of these long chromosomes is described next.
