Final answer:
Yes, mutations in the genes encoding for the enzymes gamma-secretase and beta-secretase can increase their enzymatic activity by affecting the structure and function of the active site.
Step-by-step explanation:
The enzymatic activity of gamma-secretase and beta-secretase can indeed be increased by certain mutations in the respective genes encoding those two enzymes. Mutations in genes result in changes to the amino acid sequence of the enzyme, which could potentially alter the enzyme's activity. This can lead to either increased or decreased enzymatic activity, or possibly no change at all, depending on the nature and position of the mutation within the enzyme.
As outlined in the historical context of the one-gene/one-enzyme hypothesis, established by Beadle and Tatum, there is a direct link between genes and the enzymes they produce. If a mutation occurs in such a gene, it could alter the structure and function of the resultant enzyme. Furthermore, as the mechanism of enzyme action is largely dependent on the specific arrangement and characteristics of their active sites, a mutation that affects the amino acids involved in binding or catalysis at these sites can have profound effects on the enzyme's function.