Transcript Corn genetics Lab

Chi- Squre
Goodness of Fit Test
From Ch 3
Will also include information on di-hybrid crosses
Outline
Di-Hybrid Cross
Mendel’s 2nd Law
Chi-Square Analysis
corn data (phenotypes)
DIHYBRID CROSS
Reveals Mendel’s 2nd Law
Principle of Independent
Assortment
9:3:3:1
Independent assortment
 Refers to alleles on different chromosomes!
What is the P that there are yellow and round seeds?
 ¾ x ¾ = 9/16
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
Corn genetics Lab
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 differneces
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
Genetic information regarding the corn color
patterns are provided in your lab manual.
The basis of these color patterns.
CORN WORKSHEET IS DUE 2/28/08