Transcript Corn genetics Lab

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?
Objectives
Collect data from a population of corn and
then perform Chi-Square
Interpret your findings
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 differneces
Cross C
Cross D (darker color is purple)
Cross F (call purple, may look red!)
Genetic information regarding the corn color
patterns are provided in your lab manual.
Cross C
 F1 phenotype
 F1 X F1 genotypes
 Yellow
 YYC’CRr X YYC’CRr
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?
 if. probability of observed event is due to chance alone.
To find out determine
An example of how to calculate a Chi Square
Application of Chi Square
Probability Problems
Review of some probability problems