How many different auxotrophic phenotypes are represented i

. How many different auxotrophic phenotypes are represented in your collection of three yeast strains?

Suppose you had a fourth yeast strain that was haploid and unable to synthesize the amino acid arginine. If you replica printed it onto the same kinds of plates that you used in this experiment, on which plates would it be able to grow? Explain your answer.

Strain

YPD

SD

SD + HIS

SD + LEU

SD + URA

SD + HIS + URA

SD + HIS + LEU

SD + URA + LEU

A

+

+

+

+

+

+

+

+

B

+

-

-

-

-

+

-

-

C

+

-

-

-

-

-

+

-

Strain

Phenotype

Prototroph or Auxotroph

A

Has all amino acids and nutrients needed to synthesize

Prototroph

B

Leu + His and Ura. This strain needs His and Ura to synthesize

Auxotroph

C

Ura + His and Leu. This strain needs His and Leu to synthesize

Auxotroph

Strain	YPD	SD	SD + HIS	SD + LEU	SD + URA	SD + HIS + URA	SD + HIS + LEU	SD + URA + LEU
A	+	+	+	+	+	+	+	+
B	+	-	-	-	-	+	-	-
C	+	-	-	-	-	-	+	-

Solution

There are 12 auxotropic phenotypes .

When the fourth yeast strain which is unable to synthesize arginine is replica plated onto the plates,it would be able be able to grow on all the plates if the SD is containing arginine in it. But if the SD is devoid of arginine then it will grow only on YPD and not the rest of the plates.