Genomes and mutagenesis

Figure 9.15

• The Ames test relies on a mutant bacterial strain that is defective in hisG.

• - Cannot grow on a medium lacking histidine

Identifying Mutagens

- A mutagen-containing disk is placed on an agar plate with the mutant.- Mutagen causes reversion mutations, and colonies start to appear around the disk.

Figure 9.22

• The Ames assay can be modified to test for the mutagenicity of chemicals processed in the liver.

Figure 9.23

• Transposons are complex transposable elements that carry additional genes (e.g., drug resistance).

Mobile Genetic Elements

Figure 9.34

Fig. 11-33

Gene A

Transposon Transposition

Disrupted gene 2

Gene AGene 1 Gene 3

Chromosome

Gene 1 Gene 2 Gene 3

Chromosome