Corn Genetics &

Chi- Square Goodness of Fit Test

Pedigrees and probability analysis to follow.

Outline

Highlight some key points in syllabus

Corn color and collection of data (phenotypes)

Chi-Square Analysis

Corn genetics Lab

Application of Chi-Square Analysis

The color pattern in corn is due to multiple genes

Are variations in number of observed phenotypes due to chance alone?

Objective

Complete corn worksheet

Set up Punnett Squares using the genotypes given

Compare expected data to observed data

Perform Chi Square Analysis

Variation of colors—Why?

Corn Kernel Color

Color of aleurone masks endosperm color

Only with colorless aleurone can endosperm color be determined

Determined by several genes

Refer to genotypes in lab manual!

Gene interaction can occur:

Epistasis is a form of gene interaction in which one gene masks the phenotypic expression of another.

Today there are: 3 crosses of corn

Multiple alleles are tested for expression in F2 generation

F1 X F1

Note color differences

Cross CCross D (darker color is purple)Cross F (call purple, may look red!)

Cross C

F1 phenotype

F1 X F1 genotypes

Yellow YYC’Rr X YYC’Rr

Cross D

F1 phenotype

F1 X F1 genotypes

Purple yyPpRr X yyPpRr

Cross F

F1 phenotype

F1 X F1 genotypes

Purple yyCcRr X yyCcRr

Chi Square Statistical “Goodness of Fit Test”

Why do we use it?

.To find out determine if probability are due to chance alone.

An example of how to calculate a Chi Square

Application of Chi Square

Genetic information regarding the corn color patterns are provided in your lab manual.

CORN WORKSHEET IS DUE 3/5