How do new enzyme activities arise

Aframeshift mutation causes one or more nucleotide pairs to be added or deleted and that can cause more dramatic changes in the amino acid sequences of a protein coded for by the mutated gene, with more dramatic effects on the functioning of the protein. 

New enzyme activity—it is the enzyme product not the enzymic ability that is the initial focus for selection 

If the new molecule possesses intrinsic properties which give a cost/benefit 1 then selection will favour the retention of individuals possessing that variant. Variants with a cost/benefit 1 will be lost from the population. 

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