You have discovered a new species of yeast and you would like to determine the pathway that this organism uses to synthesize the amino acid tryptophan.
This yeast species can take up tryptophan, or synthesize it on its own if tryptophan is not present in the environment. Furthermore, this yeast species is able to grow as a haploid or a diploid. Finally, two haploid cells of opposite mating types can fuse to form a diploid, and you can do this in a laboratory setting to study diploids or haploids.
You begin by collecting a set of 10 trp mutants, cells that are no longer able to grow on minimal medium unless tryptophan has been added. You label them "A" through "J". At this point, it is not clear that every mutation is in a different gene. That is, some of your mutations may have hit the same gene.
To determine the number of different genes you have mutated in your mutant collection, you conduct a complementation test. For each mutant strain, you form diploids one by one with all the other strains. You then see if the diploids can grow in the absence of tryptophan. You put your results in the table below. The symbol "+" means that the diploid can grow without tryptophan and the symbol "-" means that the diploid cannot grow without tryptophan.
A
B
C
D
E
F
G
H
I
J
A - - + + + + + + + +
B - - + + + + + + + +
C + + - + - - + + + +
D + + + - + + - + + +
E + + - + - - + + + +
F + + - + - - + + + +
G + + + - + + - + + +
H + + + + + + + - + +
I + + + + + + + + - -
J + + + + + + + + - -
(a) Based on these data, how many different complementation groups (genes) have you found in your 10 mutants? Give your answer as a numeral.
50 - incorrect
(b) Assign each of the 10 mutants into complementation groups. Express your answer as a series of letters separated by commas. For example, suppose you had the mutants P, Q, R, S, and T. Further suppose that P and Q were in one complementation group, R and T are in a second group, and S is in a third group. You would enter the answer "PQ,RT,S". Use only uppercase letters in your answer.
nvM i got the answer!
a) 5 b)AB,CEF,DG,IJ,H
To determine the number of different genes mutated in your collection of 10 mutants, you need to analyze the complementation test results. The complementation test helps determine whether mutations in different strains are located in the same gene or in different genes.
In the table provided, each row represents a mutant strain, and each column represents a different complementation test with a different strain. The "+" symbol indicates that the diploid can grow without tryptophan, while the "-" symbol indicates that the diploid cannot grow without tryptophan.
(a) To determine the number of different complementation groups (genes), you need to identify the unique patterns of "+" and "-" for each mutant strain. If two mutant strains show the same pattern of "+" and "-", they are likely mutated in the same gene and belong to the same complementation group. Conversely, if the patterns differ, they are likely mutated in different genes and belong to different complementation groups.
Looking at the table, you can group the mutants based on their patterns:
- Mutants A, B, C, E, F, G, H, I, and J all have the same pattern (+, +, +, +, +, +, +, +, -).
- Mutant D is the only one with a different pattern (+, +, +, -).
Therefore, based on these data, you have found 2 different complementation groups (genes) in your 10 mutants.
(b) To assign the 10 mutants into complementation groups, you can group them based on their patterns. The mutants with the same pattern belong to the same complementation group.
From the analysis above:
- Mutants A, B, C, E, F, G, H, I, and J belong to one complementation group.
- Mutant D belongs to another complementation group.
Therefore, you can assign the mutants as follows:
Group 1: A, B, C, E, F, G, H, I, J
Group 2: D
Expressing the answer as a series of letters separated by commas, the assignment would be:
Group 1: A,B,C,E,F,G,H,I,J
Group 2: D