You design Drosophila crosses to provide recombination data for gene a, which is located on the chromosome shown in Figure 15.12. Gene a has recombination frequencies of 14% with the vestigial wing locus and 26% with the brown eye locus. Approximately where is a located along the chromosome?

Verified step by step guidance

1. Identify the given recombination frequencies: 14% between gene a and the vestigial wing locus, and 26% between gene a and the brown eye locus.
2. Understand that recombination frequency is a measure of the distance between genes on a chromosome. The higher the percentage, the further apart the genes are likely to be.
3. Map the genes on the chromosome based on their recombination frequencies. Since 14% is less than 26%, gene a is closer to the vestigial wing locus than to the brown eye locus.
4. Use the recombination frequencies to estimate the relative positions: place the vestigial wing locus and the brown eye locus at two ends, with gene a closer to the vestigial wing locus.
5. Conclude that gene a is located approximately between the vestigial wing locus and the brown eye locus, but closer to the vestigial wing locus due to the lower recombination frequency.

Key Concepts

Recombination Frequency

Recombination frequency is a measure of the likelihood that two genes located on the same chromosome will be separated during meiosis due to crossing over. It is expressed as a percentage, indicating the proportion of offspring that exhibit recombinant phenotypes. In this case, the recombination frequencies of gene a with the vestigial wing and brown eye loci provide insight into their relative positions on the chromosome.

Genetic Mapping

Genetic mapping is the process of determining the location of genes on a chromosome and the distances between them based on recombination frequencies. By analyzing how often recombination occurs between different genes, researchers can create a genetic map that illustrates the order and relative distances of genes. This is crucial for locating gene a in relation to the vestigial wing and brown eye loci.

Chromosomal Linkage

Chromosomal linkage refers to the tendency of genes located close to each other on the same chromosome to be inherited together during meiosis. This phenomenon affects the recombination frequency; genes that are far apart are more likely to be separated by recombination than those that are close together. Understanding linkage helps in predicting the inheritance patterns of traits and locating gene a based on its recombination frequencies with other loci.