For High School Teachers
  From DNA to Organism: A Study in DNA Function for the High School Biology Classroom

Module 1: Phenotypes


          Here the students will begin the unit by looking at a number of different plants that have mutations in their genes. They will be provided with a sample of a wild-type Arabidopsis to make observations on. They will then be introduced to a number of mutant Arabidopsis plants.

Question: What are some variants that have obvious mutations that can be used to show phenotypic effects of mutations in the DNA?
Answer: i.e. no chlorophyll, too many/few leaves, too many/few flowers, too tall/short

          As the students observe the mutant plants they will answer the following questions about each of the plants:

  • How is the plant different from the wild type plant?
  • How would this difference affect this plants ability to survive in the wild?
  • What might cause this difference that you observe?

          One of the mutant plants will have a mutation in a gene encoding a K+ channel; the gene will still be present in the chromosome, but it is not functional and hence neither is the protein that it encodes. It will not have any obvious structural problems but will obviously not be doing well (wilting and/or not growing but only after a while when the K+ in the soil gets depleted). The students will be stumped by what the problem with this plant is.

     Lectures: None

     Labs: Identification of mutant phenotypes