The petite mutation in yeast

The cytoplasmic ‘petite’ mutation in yeast, which is characterized by the loss of respiratory functions, is caused by large deletions in the mitochondrial genome. The ‘petite’ mutants arise spontaneously when a segment of the wild-type mitochondrial genome, excised by an illegitimate, site-specific recombination process, is amplified to form a defective mitochondrial genome.