Question

Fifteen different strains of bacteria are suxotrophic for maltose and their mutations do not complement each other. The mutations in these bacteria map to the same DNA region using transformation of random fragments of genomic DNA. Only two different enzymes participate in the maltose biosynthetic pathway, and the genes for both are within a single operon. What does this data suggest?

O There are fifteen enzymes in maltose metabolism.
O All the strains have mutations that prevent transcription of the operon.
O Fifteen genes encode maltose biosynthesis enzymes, but only two genes are crucial
O Maltose is the preferred sugar source for the mutant bacteria.

Answer 1

The mutations in the fifteen bacterial strains suggest that the genes for the two enzymes required for maltose biosynthesis are located in a single operon. The mutations map to the same DNA region, indicating a focal point of disruption in the maltose biosynthetic pathway.

Step-by-step explanation:

The data suggests that the mutations affecting the bacteria's ability to synthesize maltose fall into two groups, corresponding to the two enzymes in the maltose biosynthetic pathway. The fact that these mutations map to the same DNA region indicates that the genes encoding these two enzymes are likely located within a single operon. Given that the mutations do not complement each other, it implies that each strain has a defect in one of the two enzymes necessary for maltose biosynthesis.

Therefore, when genomic DNA transformations are conducted, a functional copy of the mutated gene does not restore maltose biosynthesis, confirming the operon model where malfunction in any part of this operon would disrupt the entire pathway. This is in line with the understanding of operons, as established by the work of Francoise Jacob, Jacques Monod, and others, who described how genes encoding enzymes in a single metabolic pathway can be co-regulated.