Biology 22

Genetics and Molecular Biology

Fall 2007

Biology 22Fall 2007

• http://homepage.smc.edu/bober_mary

Corn Genetics Laboratory

Outline of Laboratory Discussion

Introduction to the corn kernel

Collection of data for use in Chi Square analysis

Explanation of laboratory exercise• Collection of data• Recording of data

Introduction to the Kernel

Variation of colors

Corn Kernel Color

• Color of aleurone masks endosperm color

• Only with colorless aleurone can endosperm color be determined

• Determined by several genes

Epistasis is a form of gene interaction in which one gene masks

the phenotypic expression of another.

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

The basis of these patterns.

Aleurone color determined by several genes(reference lab manual)

• R_• rr

• C’• CC or Cc• cc

• P_• pp

• Y_• yy

Purple, DominantColorless aleurone

Colorless, color inhibitorAleurone color in the presence of color allelesColorless aleurone layer in presence of R

No effect on aleurone layerChanges color to red

Yellow DominantYellow DominantWhite, RecessiveWhite, Recessive

Explanation of Corn Genetics Lab Exercise

Today’s lab has 3 crosses of corn (F2 generation=2nd filial generation)

Note color differneces

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

•Collection of data: Count kernels by cross and color

• Select 8 ears from Cross C, D and F• Count 10 rows per ear• Grand Total of 240 rows to count!

Direction of a row of kernels

Mark 10 rows

•Record Data

• Record your data at your bench by cross, ear and color

• After you are finished record your data on the spreadsheet on the computer in the front of the lab

• Class data will be on my homepage

• http://www.homepage.smc.edu/bober_mary/

Bring corn to your bench and begin counting!

Ion Exchange Chromatography

Next week lab: Ion Exchange Chromatography

Read 3-25-3-33 in lab manual.