Sordaria Lab Report

Introduction:

Sordaria fimicola is a species of microscopic fungus that is an Ascomycete and are used to test for genetic variation in the lab setting (Sordaria fimicola: A Fungus used in Genetics, Volk). These organisms are what are called model organisms, or species that has been widely studied usually because it is easy to maintain and breed in a laboratory setting and has particular experimental advantages (Sordaria fimicola, Volk). S. fimicola, because it is in the Ascomycota phylum, have a distinguishing reproductive structure called the ascus, which is surrounded by the perithecium. This cylindrical sac-like structure houses 8 haploid spores; created through meiosis to produce 4 haploid spores and then mitosis to make 8 (Lab Manual, pg. 59-68). Based on the genotype they will vary in order and color. There are 3 different ratios that can arise from the 8 ascospores: 4:4, 2:2:2:2, and 2:4:2 (black/wild type and tan coloration). The 4:4 ratio suggests that no crossing over had occurred because there is no difference in order of the color parents that were mated. The two other ratios suggest genetic recombination, or crossing over, because of the

Figure 3: Individual Data Collected

Non-recombinant Asci Recombinant Asci Total # of Recombinant Asci (B+C) / Total # of Asci (A+B+C)

# of Type A Asci

(4:4) # of Type B Asci

(2:4:2) # of Type C Asci

(2:2:2:2)

CONTROL

11 4 5

9/20 (45%)

TREATMENT: X-ray Wild Type x non-X-ray tan

6

9 5 14/20 (70%)

Figure 4: Individual Data Collected (20 asci were examined for each observation)

Figure 5: Class Data Collected

Non-recombinant Asci Recombinant Asci Total # of Recombinant Asci (B+C) / Total # of Asci (A+B+C)

# of Type A Asci

(4:4) # of Type B Asci

(2:4:2) # of Type C Asci

(2:2:2:2)

CONTROL

181 114 125

239/420 (57%)

TREATMENT: X-ray Wild Type x X-ray tan

50

63 48 111/161 (69%)

TREATMENT: X-ray Wild Type x non X-ray tan

47 43 50 93/140 (66%)

TREATMENT: X-ray tan x non X-ray Wild Type

41 45 34 79/120