1. Discuss why it would be important for a cell to have multiple levels of control of gene expression for fine-tuning the amount of product synthesis, and how that importance might be different for a bacterial cell as opposed to a cell in a multicellular eukaryote.
2. Discuss why there do not seem to be any operons in eukaryotic cells, while in bacterial cells there are numerous complete systems of structural proteins regulated by the same operator gene and repressor protein.
3. Ask students to consider why the lac operon is inducible and the trp operon is repressible, with emphasis on the kind of product and its use in each case.
4. Discuss the presence of genetic diseases in which
DNA repair is damaged and the individual has skin damage and cancer
as a result of exposure to the sun's ultraviolet rays. Consider
where the damage of the disease would be located, and why cancer
might result.