Consider a Drosophila mapping cross performed for 3 genes on the q-arm of a chro

Question

Consider a Drosophila mapping cross performed for 3 genes on the q-arm of a chromosome, with locus A located twice as far away in cM units from locus B as locus C is from B (A and C are even farther apart). Assume that from multiple cross experiments, one observes double cross-over events at a frequency of 0.086±0.04. If there is cross-over interference in the amount of -0.17, draw a genetic map and determine the distance in map units of locus A from B and locus B from C. Now, using the upper and lower bounds of the observed DCO frequency within the experimental error range, what would you expect the upper and lower bounds of the distances between these genes (i.e., A…B and B…C)?

Explanation / Answer

Three point crosses can establish gene order unambiguously. They account for double crossovers, as well as single crossovers. So, estimate map distances more accurately. Also, they allow calculation of interference parameters. Genetic map (linkage map) shows the position of genes relative to each other in terms of recombination frequency, rather than a specific physical distance along each chromosome.

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.