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Sordaria Lab

Sordaria Lab. Lab 3: Mitosis & Meiosis. Exercise 3B Studies crossing over and recombination during meiosis using asci from crosses between wild and mutants spores in the fungus Sordaria fimicola . Arrangements will be used to estimate the percentage of crossing over that occurs.

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Sordaria Lab

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  1. Sordaria Lab

  2. Lab 3: Mitosis & Meiosis Exercise 3B • Studies crossing over and recombination during meiosis using asci from crosses between wild and mutants spores in the fungus Sordaria fimicola. • Arrangements will be used to estimate the percentage of crossing over that occurs.

  3. Lab Objectives You should be able to: • Calculate the map distance of a particular gene from a chromosome's center for between two genes using an organism of your choice in a controlled experiment • Demonstrate the role of meiosis in the formation of gametes using an organism of your choice, in a controlled experiment

  4. Class: Ascomycetes (Cup Fungi) • Largest division of fungi, terrestrial • All produce spores in pouch-like asci

  5. % Crossing over

  6. Non-Crossing over

  7. Crossing over

  8. Innoculating the Plate

  9. Counting the Asci • Always 8 spores in each Asci (also called conidia) • Used in genetic recombination studies

  10. # showing crossing-over?

  11. # showing crossing-over?

  12. # showing crossing-over?

  13. # showing crossing-over?

  14. # showing crossing-over?

  15. # showing crossing-over?

  16. # showing crossing-over?

  17. # showing crossing-over?

  18. # showing crossing-over?

  19. Calculate the Map Units • Calculate the percent of crossovers by dividing the number of crossover asci (2:2:2:2 or 2:4:2) by the total number of asci x 100. • Calculate the map distance, divide the percent of crossover asci by 2. • % of crossover asci is divided by 2 because only half of the spores in each ascus are the result of crossing over.

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