A mutation in the transcription factor protein shown, protein T, disrupts the function of its DNA-binding motif. The most likely result of this mutation would be that

Question

A.  protein T can no longer directly interact with DNA, but it can still regulate gene expression through a second transcription factor.

B.  protein T can no longer interact with other transcription factor proteins, but it can still regulate gene expression by directly binding to DNA. C.  protein T can no longer regulate gene expression.

D.  protein T can still regulate gene expression by interacting directly with DNA regulatory regions.



Clarify Question

· What is the key concept addressed by the question?

· What type of thinking is required?

· What key words does the question contain and what do they mean?



  Gather Content

· What do you already know about transcription factors?

 

Consider Possibilities

· Consider the different answer options. Which can you rule out?

 

Choose Answer

· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?

 

Reflect on Process

· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

A.  protein T can no longer directly interact with DNA, but it can still regulate gene expression through a second transcription factor.

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses transcription factors.
· What type of thinking is required?
        o This question is asking you to analyze the information given, using logic, to dissect the problem and determine the answer.
· What key words does the question contain and what do they mean?
        o A transcription factor is a protein that acts to control the expression of other genes.
        o Protein T mentioned here is just a hypothetical transcription factor.
        o A DNA-binding motif is a portion of a protein that allows the protein to bind DNA.

  Gather Content
· What do you already know about transcription factors?
        o Transcription factors have a key role in the evolution of development.
        o Often transcription factors coordinate the expression of multiple target genes at once.
        o A transcription factor can have multiple regions with different functions, like DNA-binding or protein-binding motifs.
        o DNA-binding motifs can become altered by mutation so that they no longer bind to their target genes; as a result, that developmental pathway would cease to function.
        o Alternatively, the modified transcription factor might bind to a different target and initiate a new sequence of developmental events.
 
Consider Possibilities
· Consider the different answer options. Which can you rule out?
        o Would the result of the mutation be that protein T can no longer interact with other transcription factor proteins, but can still regulate gene expression by directly binding to DNA? No. If the DNA-binding motif is disrupted, it could not regulate expression by binding DNA.
        o Would the result of the mutation be that protein T can still regulate gene expression by interacting directly with DNA regulatory regions? No. Again, if the DNA-binding motif is disrupted, it could not regulate expression by binding DNA.
        o Would the result of the mutation be that protein T can no longer regulate gene expression? No. Looking at the right side of the diagram, we can see that the protein has a second way to regulate gene expression, that does not require directly binding DNA.
 
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o Would the result of the mutation be that protein T can no longer directly interact with DNA, but can still regulate gene expression through a second transcription factor? Yes. Looking at the right side of the diagram, we can see that protein T can also regulate geneexpression by binding to other proteins – not just by binding directly to DNA. If only the DNA-binding motif is disrupted, then the protein-binding function should remain intact.
 
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o This question asked what would result if the DNA-binding motif of a hypothetical transcription factor was disrupted.
        o The question required you to analyze the information given, using logic, to dissect the problem and determine the answer.
        o Did you recognize that in this case, the transcription factor can still regulate gene expression via its interactions with other transcription factor proteins?