Name __________________________________________Date _______________________ Block _______________
Evidence of Recombination in Sordaria fimicola
Post Lab Questions
1. Research and report a few interesting facts about this organism.
2. In sexually reproducing organisms, the cells that give rise to gametes are genetically identical.
The gametes produced by these cells, however, are unique. Describe two events that occur
during meiosis that result in diversity among gametes.
3. How many different gametes can be produced from an organism that has a diploid number of
eight, (2n=8)? Explain.
4. Define the term “map unit.” If a gene is 15 map units from the centromere of the chromosome,
what is the expected frequency of crossing over between the gene and the centromere?
5. Why did you divide the percentage of asci showing crossing over by 2 before determining map
distance?
6. In non-recombinant hybrid asci, the alleles for spore color segregate in meiosis I. Complete
the series of diagrams showing the progression of a pair of non-recombinant homologous
chromosomes to show that this is the case. Since the outcome of meiosis is followed by mitosis
in this organism, the result will be a 4:4 pattern.
7a. In recombinant asci, the alleles for spore color segregate in meiosis II. Complete the series of
diagrams showing the progression of a pair of homologous chromosomes to show that this is the
case.
b. For the case that you have shown, will the resulting ascus be observed in a 2:4:2 pattern or a
2:2:2:2 pattern? Explain.