Question 11
the following table shows the observed and expected crossover and non-crossover asci for the tan and gray spore genes of sordaria fimicola
from a cross between the two mutants. use the chi-squared test to determine if the gene - centromere estimated distance is significantly
different from the published map distances. [3 pt)
asci
crossover, observed
non-crossover, observed
crossover, expected
non-crossover, expected
tan spore gene
189
139
0.54 x 328) 177
(0.46 x 328) = 151
gray spore gene
204
124
0.66 x 328) = 216
10.34 x 328) = 112
only the gray spore gene is significantly different
only the tan spore gene is significantly different
both genes are significantly different
neither gene is significantly different

Option D

Neither gene is significantly different

Explanation:

Tan Spore gene

Cross-over

Observed=189

Expected=177

Observed-Expected=189-177=12

Standard deviation,

Non-cross-over

Cross-over

Observed=139

Expected=151

Observed-Expected=139-151=-12

Standard deviation,

Chi-square value=0.813559+0.953642=1.767202

Rounding off to three decimal places, chi-square value is 1.767

Gray Spore Gene

Cross-over

Observed=204

Expected=216

Observed-Expected=204-216=12

Standard deviation,

Non-cross-over

Cross-over

Observed=124

Expected=112

Observed-Expected=124-112=12

Standard deviation,

Chi-square value=0.666667+1.285714=1.952381

Rounding off to three decimal places, chi-square value is 1.952

Degree of freedom=n-1 where n is sample size, the sample size here are 2 hence degree of freedom is 2-1=1

From chi-square table, when degree of freedom is 1, chi-square value is 3.841

Since for both genes, the chi-square values are less than 3.841 then we should accept that data since it’s not significantly different

c.) polymerase chain reaction

- "unlike the original dna fingerprinting method, dna profiling does not use restriction enzymes to cut the dna. instead it uses the polymerase chain reaction (pcr)? to produce many copies of specific str sequences. pcr is an automated procedure that generates lots of copies of a specific sequence of dna."