Corn Genetics Chi Square Goodness of Fit Test

Corn Genetics & Chi- Square Goodness of Fit Test Pedigrees and probability analysis to follow.

Outline l Highlight some key points in syllabus l Corn color and collection of data (phenotypes) l Chi-Square Analysis

Corn genetics Lab

Application of Chi-Square Analysis l The color pattern in corn is due to multiple genes l Are variations in number of observed phenotypes due to chance alone?

Objective l Complete corn worksheet l Set up Punnett Squares using the genotypes given l Compare expected data to observed data l Perform Chi Square Analysis

Variation of colors—Why?

Corn Kernel Color of aleurone masks endosperm color l Only with colorless aleurone can endosperm color be determined l Determined by several genes l 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 F 1 X F 1 Multiple alleles are tested for expression in F 2 generation

Note color differences l Cross C l Cross D (darker color is purple) l Cross F (call purple, may look red!)

Cross C l F 1 phenotype l F 1 X F 1 genotypes l Yellow l YYC’Rr X YYC’Rr

Cross D l F 1 phenotype l F 1 X F 1 genotypes l Purple l yy. Pp. Rr X yy. Pp. Rr

Cross F l F 1 phenotype l F 1 X F 1 genotypes l Purple l yy. Cc. Rr X yy. Cc. Rr

Chi Square Statistical “Goodness of Fit Test” l Why do we use it? l. l. 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