It has been conclusively demonstrated that related cells can differ in their metabolic activities under various conditions. For instance, transformed cells (on their way to becoming cancerous) have more active mitochondria than do their non-transformed counterparts. TO obtain clones that differ in the level of metabolic activity associated with their mitochondria, you first treat cells in culture with a chemical mutagen.

a) Suggest an assay that could distinguish between mutants with above-normal mitochondrial metabolic activity and those with below-normal mitochondrial metabolic activity.

b) Suggest a procedure to select for mutants with above-normal mitochondrial activity.