Do I or Do I Not Complement You?

By A.K. Matai

Complementation testing is done to determine whether two mutants contain a mutation in the same genes or different genes. In research, it is practical to have various mutants that have mutations on the same gene to study its role in the native system. But before one jumps into using these mutants to study a particular gene of interest, one must learn the basics of complementation testing.

Quick Overview

If Mutant A (yellow) and Mutant B (yellow) are crossed to produce a progeny that shows a WT phenotype (red), it can be said that Mutant A and Mutant B complement one another. It also means that Mutant A and Mutant B carry mutations on different genes.

If Mutant A (yellow) and Mutant C (yellow) are crossed to produce a progeny that shows a mutant phenotype (yellow), it can be said that Mutant A and Mutant C fail to complement one another. It means that Mutant A and Mutant C carry mutations on the same gene and that Mutant A and Mutant C will form a complementation group.

Sample Problem

Here is an example of a sample problem that you may encounter on an exam. You will be will be that you will be given a complementation table and asked to figure out:

  1. Number of complementation groups
  2. Mutants associated with each complementation group
  3. Minimum number of genes in the pathway

I will walk you through a systemic approach on how to solve a sample problem that I have created.

There are 11 mutant dragons crossed to one another in a complementation test and the table bellow shows the results.A red color is wild type whereas a yellow color is mutant. How many complementation groups are represented and which mutants are associated with each?

  89 78 48 19 20 22 34 30 201 314 326
89 y                    
78 r y                  
48 r r y                
19 y r r y              
20 r r y r y            
22 y r r y r y          
34 y r r y r y y        
30 r r y r y r r y      
201 r y r r r r r r y    
314 y r r r r r r r r Y  
326 r r y r y r r y r r
y
STEP 1
  • Read the question! Often, the question descriptor is very long and contains information that is irrelevant to solving the question itself. Highlight, underline or make notes on the side to keep track of key information.
STEP 2
  • Go column by column and note down which strains fail to complement. Those that fail to complement must have a mutation in the same gene.
STEP 3
  • Notice that some of the groups are redundant. Get rid of the redundancy by combining the groups. Double check to ensure that all mutants do belong to their complementation group.
STEP 4
  • Don’t forget to answer all of the questions. In this case, write out the number of complementation groups, state the mutants which belong in each group and make sure to note any mutants that have double hits.

Do I or Do I Not Complement You SampleProblemComplementationEdited.jpg

Weekly Tip to Succeed 

Practice, Practice and Practice!! Use this method or another method to solve problems that are similar to this. That way, when you see a problem like this, you’ll be able to solve it in no time.

Questions, Comments or Concerns?

Feel free to post a comment down below! I am happy to explain or expand on anything I have written in this post.

References

Sturos, Tyler. Cat Eyes Dark Black Blue Animal Dragon Species. 2016. https://pixabay.com/en/cat-eyes-dark-black-blue-animal-1373318/. Web. 12 Jan. 2017.

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