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 F1 X F1 Multiple alleles are tested for expression in F2 generation
Note color differences Cross C Cross 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