Question

Suppose that, to determine the role of various enzymes in the tryptophan pathway, a research scientist created three mutant bacteria strains, wherein each mutant strain corresponds to an inactivated enzyme. Mutant 1 has an inactivated enzyme 1, mutant 2 has an inactivated enzyme 2, and mutant 3 has an inactivated enzyme 3. The scientist then attempted to grow these strains on media with different supplements. Use the depicted biochemical pathway to complete the predicted growth table for each mutant on minimal media plus the specified added supplement, where + indicates growth and 0 indicates no growth. Enzyme 1 Enzyme 2 Enzyme 3 Anthranilic acid - Indole glycerol phosphate - Indole -Tryptophan Minimal medium + Mutant strain Anthranilic acid Indole glycerol phosphate Indole Tryptophan + + 20 + Answer Bank

Answer 1

The completed table will be:

Mutant strain	Anthranilic acid	Indole glycerol phosphate	Indole	Tryptophan
1	0	+	+	+
2	0	0	+	+
3	0	0	0	+

If minimal media is supplemented with Anthranilic acid, then no mutants can grow; because Tryptophan would not be synthesized.

If minimal media is supplemented with Indole glycerol phosphate, only mutant 1 can grow; but mutants 2 and 3 will not synthesize further.

If minimal media is supplemented with Indole, then mutants 1 and 2 can grow; but mutant 3 can not synthesize tryptophan from indole and will not grow.

If minimal media is supplemented with Tryptophan, then all of the mutants can grow. Because they don't have to catalyze any intermediate steps to produce tryptophan.