1. Types of mutations
2. Mechanism of mutagenesis and DNA repair
3. Auxotrophic mutants and the Ames test

1. The concepts covered here can be reviewed in your textbook, pages 228-231, and your lecture notes.

2. Sometimes scientists induce mutations in bacteria (for research or practical purposes). The mutant cells have to be identified somehow (and a large number of mutants have to be screened). Review the material about auxotrophic mutants and answer the following questions:

• What is the definition of an auxotrophic mutant?
• How can we identify an auxotrophic mutant by growing it on minimal and supplemented defined media?

3. Now that you know what an auxotrophic mutant is, apply your knowledge to identify which of the following colonies represent such auxotrophic mutants. For each colony marked with a letter, write down if it is an auxotrophic mutant or no, and WHY you answered that!

4. If you feel that you have mastered the concepts in this sub-unit, you can move to the next sub-unit, which explores horizontal transfer in bacteria.