1 A student is asked to characterise six yeast strains label

1. A student is asked to characterise six yeast strains labelled 1, 2, 3, 4, 5 and 6. The student begins by streaking cells of each strain onto nine different tester media shown in Table I. Table l: Growth responses of the six strains on different tester media strain YEPD MM MM A MM L MM H MM +A L L H H H Legend growth and no growth, MM minimal medium, YEPD complete medium L leucine, A- arginine, and H histidine (each is an end product of a separate biochemical pathway, all are required for growth i) Using only the data from Table i, determine the genotype of each strain, using the same format as the wildtype strain. For this question only, assume there is only 1 gene/ pathway ie. Only 1 enzyme involved in making histindine, one enzyme to make arginine, etc. (3 pts) Strain Genotype Strain Genotype Wildtype arg leu his 6

Solution

Genotype of each strain:

Wild type:- arg⁺; leu⁺; his⁺

1. arg^-; leu^-; his^-

2. arg⁺; leu⁺; his^-

3. arg^-; leu⁺; his⁺

4. arg^-; leu^-; his^-

5. arg⁺; leu^-; his⁺

6. arg^-; leu⁺; his⁺

3.

Genotypes of strain 1.

arg1; ARG2; LEU1; leu2; HIS1; his2

Genotypes of strain 3.

arg1; ARG2; LEU1; LEU2; HIS1; HIS2

Genotypes of strain 4.

arg1; ARG2; LEU1; leu2; HIS1; his2