Sydney Brenner isolated Salmonella typhimurium mutants that were implicated in t
ID: 216454 • Letter: S
Question
Sydney Brenner isolated Salmonella typhimurium mutants that were implicated in the biosynthesis of tryptophan and would not grow on minimal medium. When these mutants were tested on minimal medium to which one of four compounds, anthranilic acid, indole, indole glycerol phosphate, or tryptophan, had been added, the growth responses shown in the following table were obtained. A + indicates that the bacterial mutants were able to grow on the medium, and a - indicates the bacterial mutants were not able to grow on the medium.
Mutant Minimal Anthranilic Indole media acid phosphate glycerol Indole Tryptophan trp-1 trp-2_ rp-3_ trp-4- rp-5- rp7_ trp-8- rp-9 rp-10Explanation / Answer
(trp-8) (trp-2 and 4) (trp-3)
Precursor -------? anthranilic acid -------? Indole glycerol phosphate -------
(trp-1,10,11,9,6,7)
-------? indole -------? Tryptophan
Group 1 mutants are able to grow only on the minimal medium supplemented with trpytophan. Group 1: trp 1, trp 10, trp 11, trp 9, trp 6, and trp 7.
Group 2 mutants are able to grow on the minimal medium supplemented with either trpytophan or indole. Group 2: trp 3.
Group 3 mutants are able to grow on the minimal medium supplemented with tryptophan, indole, or indole glycerol phosphate. Group 3: trp 2 and trp 4.
Group 4 mutants are able to grow on minimal medium supplemented with the addition of tryptophan, indole, indole glycerol phosphate, or anthranilic acid. Group 4: trp 8.
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