F2 maize kernel count is as follows 450 purple and smooth 49

F_2 maize kernel count is as follows: 450 purple and smooth, 49 yellow and wrinkled, 155 purple and wrinkled, 145 yellow and smooth. (A) How many genes are involved? _______ How many alleles per gene are involved? _______ (B) Is this a result of a monohybrid or a dihybrid cross? _______ (C) Fill in the genotypes of the P_1: _______ x _______ F_1: _______ Explain your allele labeling. (D) The expected F_2 phenotypic ratio of kernels is (write down the numbers along with corresponding phenotypes): (E) State the complete null hypothesis for this experiment: (F) What is the purpose of Chi-square test? (G) What is the formula for the Chi square test? _______ (H) Calculate the Chi square, show your calculations in a table (as done in class) _______ (I) Calculate the degrees of freedom (J) State the p value based on your calculations. Explain how you determined the p value. (K) What can you conclude regarding the null hypothesis? (L) State the critical p value and its significance _______

Solution

F2 maize kernel count is as follows

450purple and smooth

49 yellow and wrinkled

155 purple and wrinkled

145 yellow and sm0oth

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Parental Phenotype

Purple, Smooth Kernels    x Yellow, Wrinkled Kernels

              Genotype       AABB       x    Genotype    aabb

F1 Phenotype--------------- Purple, Smooth Kernels

Genotype AaBb    

Genotype AaBb     x Genotype AaBb    

AB

Ab

aB

ab

AB

AB AB

Ab AB

aB AB

ab AB

Ab

AB Ab

Ab Ab

aB Ab

ab Ab

aB

AB aB

Ab aB

aB aB

ab aB

ab

AB ab

Ab ab

aB ab

ab ab

F2 Phenotypes*

F2 Phenotypes

genotypes

Observed

Yellow, Wrinkled Kernels

aabb

49

Yellow, Smooth Kernels

aaBb, aaBB

145

Purple, Smooth Kernels

AaBb, AABB, AaBB, AABb

450

Purple, Wrinkled Kernels

Aabb, AAbb

155

A)

LOCUS1

PURPLE - kernel --------DOMINANT ALLELE

YELLOW - kernel --------RECESSIVE ALLELE

===============

LOCUS 2

SMOOTH --------DOMINANT

WRINKLED --------RECESSIVE

B) TWO ALLELES

C) DIGYBRID CROSS

F2 generation,-EXPECTED RATIO ; 9:3:3:1

The pattern above corroborates with a Mendelian mode of inheritance:

The breeding of two true breeding strains results in a single F1 progeny indicating that the purple kernel and the smooth kernel traits each correspond to dominant phenotypes,

whereas the yellow kernel and the wrinkled kernel traits correspond to recessive traits.

In the F2 generation, we find that the kernel color gene and the kernel texture gene are unlinked, or likely to be on different chromosomes.

These F2 progeny are the result of segregation of alleles and independent assortment during meiosis

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F2 Phenotypes

genotypes

Observed

EXPECTED

(O-E)^2/E

Yellow, Wrinkled Kernels

aabb

49

50

(49-50)^2/50

0.02

Yellow, Smooth Kernels

aaBb, aaBB

145

150

(145-150)^2/150

0.16

Purple, Smooth Kernels

AaBb, AABB, AaBB, AABb

450

499

(450-499)^2/499

4.81

Purple, Wrinkled Kernels

Aabb, AAbb

155

150

(155-150)^2/150

0.16

799

799

5.15

NULL HYPOTHESIS:

F2 progeny are the result of segregation of alleles and independent assortment.

ALTERNATIVE HYPOTHESIS

F2 progeny are the NOT result of segregation of alleles and independent assortment.

======================

Chi-Square Test (df=3)

CALCULATED Chi-square =5.15

CALCULATED Chi-square 5.15 IS MORE THAN TABLE VALUE AT 5% LEVEL OF SIGNIFICANCE

ACEPT NULL HYPOTHEIS

F2 progeny are the result of segregation of alleles and independent assortment.

	AB	Ab	aB	ab
AB	AB AB	Ab AB	aB AB	ab AB
Ab	AB Ab	Ab Ab	aB Ab	ab Ab
aB	AB aB	Ab aB	aB aB	ab aB
ab	AB ab	Ab ab	aB ab	ab ab