Question

Determine the probable mode of inheritance of each phenotypic trait, the genotypes associated with each phenotype and the ratios of genotypes and phenotypes expected in crosses if your model is correct. You will confirm this by using a chi-square test. Wild Population - 100 mice (1 to 100) Both parents collected from the wild Vision FM Total Blind 4 5 9 Wild Type 45_46 91 Line 1 - 162 mice (101 to 262) Parents: (Vision) M: (Vial O, #1) Wild Type F: (Vial O, #2) Wild Type Vision FM Total Blind 27 21 48 Wild Type 70_44 114 Line 2 - 55 mice (263 to 317) Parents: (Vision) M: (Vial 1, #102) Wild Type F: (Vial 1, #101) Wild Type Vision FM Total Blind 6 10 16 Wild Type 19 20 39 Line 3 - 57 mice (318 to 374) Parents: (Vision) M: (Vial 2, #264) Blind F: (Vial 2, #263) Wild Type Vision F M Total Blind 14 14 28 Wild Type 11 18 29 Possibilities for mode of inheritance are dominant/recessive, X-linked dominant/recessive, lethal, co-dominant/semi-dominant. Sometimes, if are dealing with multiple genes, the genes might be on the same chromosome (i.e. they might be linked) in which case you will need to determine the map distance between the genes.

Answer 1

Wild population- OBSERVED

	FEMALE	MALE	TOTAL
VISION	4	5	9
BLIND	45	46	91
TOTAL	49	51	100

EXPECTED

	FEMALE	MALE	TOTAL
VISION	(9 * 49) / 100 = 4.41	(9*51) / 100 = 4.59	9
BLIND	(91* 49) / 100 = 44.59	( 91 * 51) / 100 = 46.41	91
TOTAL	49	51	100

CHI square test

chi square = (Observed- Expected)2 / Expected

female

PHENOTYPE	OBSERVED	EXPECTED	( O-E)	( O- E )2 / E
VISION	4	4.41	0.41	0.038
BLIND	45	44.59	0.41	0.0037
TOTAL				0.0417

male

phenotype	observed	expected	O -E	( O- E)2 / E
vision	5	4.59	0.41	0.0366
blind	46	46.41	-0.41	0.0036
total				0.0402

wild type- 0.0819

Lane 1

	female	male	total
vision	27	21	48
blind	70	44	114
total	97	65	162

expected

	female	male	total
vision	28.75	19.25	48
blind	68.25	45.75	114
total	97	65	162

Chi square test

female

phenotype	observed	expected	O- E	( O- E)2 / E
vision	27	28.75	-1.75	0.1065
blind	70	68.25	1.75	0.0448
total				0.1513

male

phenotype	observed	expected	O-E	( O- E )2 / E
vision	21	19.25	1.75	0.1590
blind	44	45.75	-1.75	0.0669
total				0.2259

0.3772- heterozygote

similar steps can help to prove 1: 2: 1 ratio