Question

Need the one that is bolded.

Assume that we have isolated five mutants, 1 to 5, that cannot synthesize compound G for growth. We know the five compounds, A to E, that are required in the biosynthetic pathway, but we do not know the order in which they are synthesized by the wild-type cell. We have tested each compound for its ability to support the growth of each auxotroph, with the following results (a plus sign means growth and a minus sign means no growth):

What is the order of compounds A, B, C, D, and E in the pathway, and also assign the specific gene (mutant that impair the specific step) at the specific conversion steps that is responsible for the metabolism of the compounds tested.

            E – A – C – B – D – G

Answer 1

Mutation causes the inhibition or prevention of the formation of product in the metabolic pathway due to the loss of function of the immediate step causing the conversion of substrate into that specific product. If a compound is added that is causing the formation of product before the mutation which is later causing inhibition in the metabolic pathway will also not yield the final products and will be stopped at some intermediate stage after the initial formation of some products but the final product will not be formed. However if later products are added in the auxotrophic medium or some other products are added that favor the enzymes leading to the formation of the intermediate products, then the final product G will be formed therefore G is the final product in the pathway. Therefore the order of the metabolic substrates will be E-A-C-B-D-G. E will be first product as it is not supporting the production of any product after the addition of artificial substrates, then A will be formed, then C will be formed, then B will be formed, then D will be formed and then G will be formed finally. A will be supporting the formation in only one mutant, B will be supporting the formation of product in three mutants, C will support the formation of two mutants,addition of D will support the growth of four mutants and addition of E will not support the growth of any mutant so it is formed first in the metabolic pathway. Addition of G will support the formation of all mutants so G is the final product in the metabolic pathway.

A standard table of the formation of the different products in the metabolic pathway is given below as follows:

and the number order of products formed in the pathway is given below as follows: