What Caused the Ghostly Leaves? Inquiry-Based Investigation of the Genetics and Molecular Biology of Corn Albinism

 

Caldwell, J. & K. Teagarden

Tested Studies in Laboratory Teaching, 2010, Volume 31

Abstract

This inquiry-based exercise spans two weeks in lab. Students examine the genetics and inheritance of the trait of albinism (chlorophyll deficiency) in corn. Students examine 3 week old corn plants grown from a monohybrid cross, in which the recessive gene is for chlorophyll deficiency. The nature of the original cross is not revealed to the students. Students form hypotheses about the cause of the albino trait, including the number of genes involved, how they are inherited, and what the effect on the protein composition will be. During the lab exercise students count the number of plants and calculate ratios. They use this data and Punnett squares to examine inheritance, and also examine the effects of sample size by comparing ratios calculated from different numbers of plants. They also extract full cellular protein from white and green leaves, and run those extracts on a gel. Students compare extracts from white versus green corn to determine how many proteins were involved in causing the trait. They compare their results from genetic analysis and gel electrophoresis to validate or revise their original hypotheses. From this lab, students learn the basics of genetics, gel electrophoresis, and sample size in an inquiry-based format. This lab is intended for non-science majors, and has been streamlined to occur over two, two-hour lab periods in consecutive weeks, but can easily be adapted for more advanced classes. Such adaptations could include (1) more extensive involvement in reagent and sample preparation, (2) more involvement in preparing, running, and loading the gel, and (3) examination of the original literature on chlorophyll deficiency, to determine which specific gene is involved.

Keywords:  Molecular Biology, genetics, gene regulation, proteomics, non-majors

University of Delaware (2009)