Complementation tests

How do we figure out how many enzymes are responsible for one step in a biochemical pathway? What does it mean to say that two mutants "complement" each other? What is a complementation group? This video lecture was recorded at the University of Wisconsin -- Stout in the fall of 2021. It accompanies my BIO 332 Genetics course, which was taught with Hartl's "Genetics: Analysis of Genes and Genomes."