Our class met mutants are derived from strain BY4742, which has the genotype MATa his3-∆1 leu2∆0 lys2∆0 ura3∆0. The defined media are based on YC, which contains histidine, leucine, lysine and uracil. YC Complete medium also contains methionine and sulfate, so we will use “dropout” media to test the ability of strains to grow on various sulfur sources. Modifications to YC are as follows:
YC-Met methionine has been removed from the YC
YC-Met+Cys cysteine has been added to YC-Met plates
YC-Met+SO3 sulfite replaces sulfate in YC-Met plates
Predict the ability of met mutants to grow on various sulfur sources and complete the table below. Place a plus (+) when you predict that the strain will grow on the plate and a minus (-) when you do not expect the strain to grow.
BiGGY agar plates are used to detect sulfide production. Use upward- and downward- facing arrows to predict whether strains will give rise to darker or lighter colonies than BY4742.