2. Bacteria may synthesize many of the amino acids needed for growth. A bacteria
ID: 269302 • Letter: 2
Question
2. Bacteria may synthesize many of the amino acids needed for growth. A bacterial culture was exposed to a mutagen, and mutant strains were isolated that could not grow in the absence of added tryptophan (T). The wild-type strain grew in the absence of tryptophan. Compounds D, E, F, and G are intermediates in the pathway for the synthesis of T from C. From the data in the following table, order the compounds in the pathway Note that + indicates growth and 0, no growth. ADDITION TO THE MEDIUM MUTANT STRAIN A. C, E, F, D, G,T B. C, F, D, E, G, T C. C, F, E, D, G, T D. C, G, E, F, D, T E. C, E, G, F, D, T ahin which of theExplanation / Answer
Answer- C
The steps involved in biosynthesis of Tryptophan are C->F->E->D->G->T
To determine the order you count the number of sensitive mutants in supplemtation of each intermediate compunds. Any intermediate supplementation having higher number of sensitive mutants comes at the earlier steps of the biosynthetic pathway.
Supplementation with C can not rescue growth of any of the mutants suggest its involvement at the first step of the biosynthetic process.
Supplementation of F can rescue only Mutant4 suggesting its second place in the order. Enzyme 4 is required for synthesis of F from C.
Supplementation of E can rescue mutant 4,2 suggesting its third place in the otder. Enzyme 2 is required for conversion of F->E.
Supplementation of D can rescue mutation 4,2 and 3 suggest fourth place in the biosynthetic process. Enzyme 3 is involved in conversion of E->D.
Supplementation of G can rescue the mutation 4,2,3 and 1 suggest its fifth place in the biosynthesis order. Also enzyme 1 is involved in biosynthesis of G from D.
Finally Tryptophan supplementation rescues senstivity of all mutants because it is the final product of the biosynthesis process.
The enzymes involved in this pathways are C-4>F-2>E-3>D-1>G-5>T
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