Question

B 3 - E- F 5 The figure above showing a branched metabolic pathway leading to the synthesis of two related amino acids (D and F) in N. crassa. Both are required for growth. 5 pts I) If an N. crassa strain has a genetic defect that results in nonfunctional Enzyme 1, could the strain grow if supplemented with compound C in minimal medium? If a strain carries a mutation in the gene encoding Enzyme 2, will it be able to grow on minimal medium? Will it be able to grow if supplemented with C? Will it be able to grow if supplemented with E? V) Will it be able to grow if supplemented with B? II)

Answer 1

1. If the stain has defect in Enzyme 1, the stain will not grow even if supplement with compound C in minimal medium. This is because compound C can form only amino acid D. But both amino acids D and F are required for growth. Supplementation with C can’t form amino acid F.
2. If the strain carries a mutation in the gene encoding Enzyme 2, it will not grow in the minimal medium as defective Enzyme 2 can’t produce compound C which is necessary for amino acid D synthesis.
3. If the strain carries a mutation in the gene encoding Enzyme 2, it will be able to grow in the minimal medium supplemented with compound C. This is because compound C is enough for synthesis of amino acid D.
4. If the strain carries a mutation in the gene encoding Enzyme 2, it will not grow in the minimal medium supplemented with compound E. This is because the medium lack compound C which is important for the production of amino acid D.
5. If the strain carries a mutation in the gene encoding Enzyme 2, it will not grow in the minimal medium supplemented with compound B. This is because the defective Enzymes 2 can’t convert B into C which is important for the production of amino acid D.