The following table presents the effect of different media on the growth response of tryptophan mutations in Salmonella typhimurium (+ = growth, - = no growth)
Medium Supplemented with
Strain No Supplement IGP AA IN TRY
trp-8 - + + + +
trp-2 - + - + +
trp-3 - - - + +
trp-1 - - - - +
(a) Construct the biochemical pathway for the compounds IGP, AA, IN, and TRY based on these data.
(b) Place strains of bacteria (mutations) in the appropriate steps in the pathway.
(c) In bacteria, it is often possible to make partial diploid strains. Assume that a diploid strain was made containing the complete genomes of the trp-2 and trp-1 strains. Would this diploid strain be able to grow on the unsupplemented medium? Explain your answer.
(a) ? + ? >AA ? + ? >IGP ? + ? >IN ? + ? Try
(b) ? + ? >AA ? + ? >IGP ? + ? >IN ? + ? Try
? ? ? ?
8 2 3 1
(c) Yes, complementation will occur because the trp-2 strain is also trp-1+ and the trp-1 strain is also trp-2+.
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