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

Module 1: Phenotypes

Teacher suggestions for Module 1 

     Timing


Rounded Rectangle: Teacher Desk           1 period (4560 minutes)

     What you need to set up per 24 students

  • Get/grow 4– 6 different mutant Arabidopsis strains (i.e. dwarf, colored leaves, etc. )
    • 3– 5 plants per station
    • See suggested strains on next page
  • Stations for each of the mutant plants
  • 2– 3 data sheets for each student
  • Colored pencils for drawings

     What the students need

  • Notebook
  • Rulers or tape measures

            Set up the plants at different stations around the room, with groups of similar mutants at each station. Groups of 3– 5 plants should be sufficient for the observations.   The student groups will travel from mutant to mutant to make observations on each.   You may want to time each station to avoid bunch ups, i.e., 5 minutes per station, then prompt the groups to rotate to the next station. They may realize characteristics that are important during their observation period and may need to go back to some stations to re-measure.

     Prelab 10 minutes

           Reading of the letter and review of procedures for the lab.

     Lab 30-40 miutes

           Actual examination of the different plants and compilation of group data.

     Postlab 10-20 minutes

           The idea here is that the students will look at the plants and be able to identify the differences. By providing them a wild type plant, you are giving the students something to compare the mutant plants to. It is a good opportunity to talk about variation in data, and the need to measure all of the plants to get an average. There will also be opportunity to discuss the difference between qualitative (color) and quantitative data (height, number of leaves). The main goal of this module is to get the students thinking about plants and why individuals of the same species might look different. It provides a good opportunity to introduce the concept of a mutation being a change. Postlab discussion should also include a discussion of what affects the mutations have on the life of the plant, i.e., how would a dwarf plant do in the wild?

     Homework

           Write a letter back to Dr. Berkowitz explaining their findings. The letter can be modeled after a lab write up by having the students include in the letter:

  • What they did
  • Why they did it
  • How they did it (including data collection techniques)
  • What they discovered
  • What it means

     How to choose and get strains of seeds

           The Arabidopsis Information Center (TAIR) runs a Web site, www.arabidopsis.org, which gives information and links to all things Arabidopsis. They also are connected with the Arabidopsis Biological Resource Center (ABRC) at Ohio State University, which maintains stock lines for many of the wild-type and mutant strains of the species. A link to the ABRC Web site, http://www.biosci.ohio-state.edu/~plantbio/Facilities/abrc/abrchome.htm is located under the heading “Stocks” on the TAIR homepage. Seeds for the various geno/phenotypes that they have can be ordered using the “Order Stocks” option on the main page. You will have to register before you can order but this is not a problem.

           A number of seeds were tested for use in Module 1 and the following worked well to illustrate the idea of mutant phenotypes to the students.

Seed Stock #

Description

CS60000*

Wild-type plant

CS3762*

akt1 mutants (no K+ channel)

CS50

Dwarf plant

CS254

Broad round leaves

CS271

Variegated leaves

CS3119

Greenish/yellow plant (no chlorophyll B)

CS3257

Serrated leaves

CS5986

White seedling (lethal)

* Needed for future modules

           You can also browse the available lines by using the “Browse Catalog” option on the ABRC Web site. From there, click on the “Characterized Lines” under the heading “mutants.”  This will allow you to look over descriptions of all of the lines that they have. Many of the lines even have pictures that you can look over. They had some 1700+ lines as of July 2005 and the number increases as more people donate their new mutant lines. Happy hunting!