Lesson 1 – Scientists Prepare and Plan

Course:  Biology, Genetics, Biotechnology, Environmental Science

Unit:  Genetics and Heredity


See Standards Addressed for all NGSS and WA State (Science, Math and Literacy).  In addition to the aligned objectives linked above, for this lesson, here is a breakdown of:

What Students Learn:
  • Observations lead to hypotheses and experimental design.
  • Halobacterium (Halo) respond to changes in their environment, such as the amount of light.
What Students Do:
  • Students use scientific thinking to consider how the environment impacts gene expression and cellular networks.
  • Students conduct research into current Halobacterium observations and make a list of possible variables (which leads to lesson 2).








Pacing Guide

Instructional Activities: (One 50-min period, with a bit of homework if needed)

Before beginning lesson: see Advanced Prep for help with lab set up and advance preparation for this and other lessons.


Students should complete these lessons near the end of a genetics unit.  Typically students would have learned that organisms (and individual cells of multicellular organisms) respond to their environment by changing which proteins they make.  A major way they do this is by regulating ”gene expression” through control of transcription.  Some genes are “turned on” to make mRNA for their corresponding protein, and some genes are “turned off” to stop making mRNA for their corresponding protein.  This allows the cell to conserve energy by producing only what is needed at that time.

This is usually studied in high school classrooms in a fairly artificial situation.  E. coli bacteria are transformed by adding plasmid DNA, and their environment is changed with the addition of the molecule arabinose.  The gene for green fluorescent protein (GFP) is “turned on” (transcribed) in the presence of arabinose and “turned off” (not transcribed) in the absence of arabinose.  This serves as a good model system to study these processes, but E. coli bacteria in nature do not have the gene for GFP, and they do not respond to the molecule arabinose in this manner.

To study this in a more natural situation where an organism’s DNA is not altered, we will use the model system of Halobacterium (Halo), which lives in high salt environments such as the Great Salt Lake.  This module will give students a way to act as scientists as they study how this organism responds to changes that occur in its natural environment.  They will use networks as part of their experimental process in the same way scientists use networks to hypothesize, model, and predict cellular responses to environmental cues.