A researcher is interested in delineating the pathway for the production of blue

Question

A researcher is interested in delineating the pathway for the production of blue colony color in yeast. She finds that it is possible to mate two mutant "gray colony" strains of yeast and produce diploid yeast cells that produce blue colonies. [Haploid yeast occur in two different "mating types." If two haploid cells of opposite mating types meet, they can fuse and enter a diploid phase of the yeast cell cycle.] The researcher then proceeds to mate nine different "gray colony" yeast mutants (A through I) in all pairwise combinations and subsequently inspects the diploid progeny for colony color. The results of her complementation analysis are presented in the table below; b = blue colonies and g = gray colonies.

Part A

What is the minimum number of genes necessary for the production of blue colony color in yeast?

Part B

List the mutants that are included in each complementation group.

Enter your answer as follows: Represent the mutants in each complementation group as the list of uppercase letters in alphabetical order within a set of parentheses). Do not leave any spaces between the letters or between the adjacent parentheses group. For example: (ABCD)(EFG)(H)(I)

A researcher is interested in delineating the pathway for the production of blue colony color in yeast. She finds that it is possible to mate two mutant gray colony strains of yeast and produce diploid yeast cells that produce blue colonies. [Haploid yeast occur in two different mating types. If two haploid cells of opposite mating types meet, they can fuse and enter a diploid phase of the yeast cell cycle.] The researcher then proceeds to mate nine different gray colony yeast mutants (A through I) in all pairwise combinations and subsequently inspects the diploid progeny for colony color. The results of her complementation analysis are presented in the table below; b = blue colonies and g = gray colonies. Part A What is the minimum number of genes necessary for the production of blue colony color in yeast? Part B List the mutants that are included in each complementation group. Enter your answer as follows: Represent the mutants in each complementation group as the list of uppercase letters in alphabetical order within a set of parentheses). Do not leave any spaces between the letters or between the adjacent parentheses group. For example: (ABCD)(EFG)(H)(I)

Explanation / Answer

To calculate number of genes necessary for production of blue colonies in yeast, we first need to identify the complementation groups and their number. This number is achieved by looking at each pair of mutants given and then looking for complementation between them. Three points to identify complementation groups are :

(i) A mutant never complements itself.

(ii) Blue colony appeared (b) means that the mutants complement each other. When mutants complement it means that they belong to different complementation group.

(iii) Gray colony appeared (g) means that the mutants do not complement each other. When mutants do not complement it means that they belong to the same complementation group.

Proceeding down the rows, we see that A complements with C,B and I.This means that they belong to different complementation groups. C does not complement with I. This means that C and I belong to the same group. E belongs to an entirely different group because it complements with all.

So now we have 3 groups:

Group A- ABDFGH

Group B- CI

Group C- B

Since, we have 3 complementation groups this means that there are atleast 3 genes controlling the blue colony formation in yeast. From this we can answer both the parts.

Part A-

The minimum number of genes necessary for the production of blue colour colony in yeast is 3.

Part B-

(ABDFGH)(CI)(E)

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