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.