Wednesday, April 13, 2011

Lab 06 - Gene mapping - Drosophila

Tuesday, April 12, 2011

Today we did lab 06, on mapping genes in Drosophila.

We discussed concepts like linkage, recombination, crossing over, and as a consequence how phenotypic categories deviate from Mendelian proportions. We mentioned how genes that are in the same chromosome may also be unlinked, if the distance between them (measured in centimorgans (cM) is big enough.

Using DrosophiLab, a crossing-over simulator (from Paul Lewis' lab), and paper and pencil, students learned:
  • How to determine the distance between two genes in the same chromosome (measured in cM or map units (M.U.))
  • The effect of the distance between genes and the size of a chromosome in the frequency of recombinant chromosomes during meiosis
  • How to map genes based on gene distances
  • How to map genes and find the distances between them based on phenotypic data (resulting from simulated crosses).  We did this for three genes, using a three-point test cross.
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