Homework Assignment #4 Answers
Question #1a
| Cross |
Overall
Ratio |
df |
Probability |
| 1 |
2.126 |
3 |
0.75
- 0.5 |
| 2 |
6.596 |
3 |
0.1-0.05 |
| 3 |
65.99 |
3 |
less
than 0.005 |
| 4 |
11.601 |
3 |
0.01-0.005 |
Test Ho:1:1:1:1 ratio
Cross 1: X
=(310-300)+(287-300)+(288-300)+(315-300)
300
300
300
300
Cross 1: X
= 0.333 + 0.563 + 0.480 + 0.750 = 2.126
Cross 2: X
= (36-30)
+ (23-30)
+ (23-30)
+ (38-30)
30
30
30
30
Cross 2: X
= 1.20 + 1.63 + 1.63 + 2.13 = 6.59
Cross 3: X
=(360-300)+(230
- 300)+(230
- 300)+(380
- 300)
300
300
300 300
Cross 3: X
= 12 + 16.33 +16.33 + 21.33 = 65.99
Cross 4: X
= (74-60)
+ (50-60)
+ (44-60)
+ (72-60)
60 60
60
60
Cross 4: X
= 3.267 + 1.667 + 4.267 + 2.4 = 11.601
Test Ho: independence between A and B loci.
Cross 1: X
= (310 - 287 - 288 + 315)
= 2.083
1200
Cross 2: X
= (36 - 23 - 23 +38)
= 6.533
120
Cross 3: X
= (360 -230 - 230 +380)
= 65.33
1200
Cross 4: X
= (74 - 50 - 44 - 72)
= 11.267
240
Summary
| Cross |
X |
X |
X |
df |
overall |
df |
| 1 |
0.03 |
0.013 |
2.083 |
1 |
2.126 |
3 |
| 2 |
0.033 |
0.033 |
6.533 |
1 |
6.596 |
3 |
| 3 |
0.333 |
0.333 |
65.330 |
1 |
65.990 |
3 |
| 4 |
0.267 |
0.067 |
11.267 |
1 |
11.601 |
3 |
| Sum |
0.663 |
0.446 |
85.213 |
4 |
86.313 |
12 |
Question #1b
Test Ho:1:1 for locus A
X
= (780 +590 - 585 -805)
= 0.1449
2760
Cross 1: X
= (310 + 287 - 288 - 315)
= 0.03
1200
Cross 2: X
= (36 + 23 - 23 - 38)
= 0.033
120
Cross 3: X
= (360 + 230 - 230 - 380)
= 0.333
1200
Cross 4: X
= (74 + 50 - 44 - 72) = 0.267
240
Test Ho:1:1 for locus B
Cross 1: X
= (310 - 287 + 288 -315)
= 0.013
1200
Cross 2: X
= (36 - 23 + 23 - 38)
= 0.033
120
Cross 3: X
= (360 - 230 + 230 -380)
= 0.333
1200
Cross 4: X
= (74 - 50 + 44 - 72)
= 0.067
240
Heterogeneity Test
Ho:1:1 for locus B.
X
= (780 - 590 + 585 - 805)
= 0.3261
2760
Ho:A and B loci segregate independently.
X
= (780 -590 - 585 + 805)
= 60.91
2760
Summary
| Cross |
X |
X |
X |
df |
| 1 |
0.030 |
0.013 |
2.083 |
1 |
| 2 |
0.033 |
0.033 |
6.533 |
1 |
| 3 |
0.333 |
0.333 |
65.330 |
1 |
| 4 |
0.267 |
0.067 |
11.267 |
1 |
| Total |
0.6630 |
0.4460 |
85.213 |
4 |
| Overall |
0.1449 |
0.3261 |
60.910 |
1 |
| Heterogeneity |
0.5181 |
0.1199 |
24.303 |
3 |
Conclusion:
There is no evidence of distortions in the segregation ratio at either
the A or B locus in any of the four crosses. This result is homogenous.
There is evidence that the A and B loci do not segregate independently
for crosses 2, 3, and 4. Cross 1 does segregate independently between
the A and B loci. There is heterogeneity for independent assortment
among the four crosses. The four families should not be pooled to determine
an overall estimate of the recombination faction.
Question #2
| Cross |
^
p
|
Linkage |
| 1 |
0.48 |
none |
| 2 |
0.38 |
coupling |
| 3 |
0.38 |
coupling |
| 4 |
0.39 |
coupling |
