In your research, you have discovered that Protein X is often ubiquitinated in people with a certain disease. What would you predict about levels of Protein X in these patients?

Question

A.  Levels of Protein X will be low due to degradation in the proteasome.
B.  Levels of Protein X will be the same, just carrying a ubiquitin tag.
C.  Levels of Protein X will be increased due to transcriptional activation.
D.  Levels of Protein X will be decreased due to negative feedback on transcription.
E.  Levels of Protein X will be increased due to protection from degradation.

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 ubiquitination?

Consider Possibilities
· What other information is related to the question? Which information is most useful?

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.  Levels of Protein X will be low due to degradation in the proteasome.

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses ubiquitination.
· What type of thinking is required?
        o This question is asking you to take what you already know and apply it to this unfamiliar situation.
· What key words does the question contain and what do they mean?
        o Ubiquitinated proteins carry a ubiquitin tag.

Gather Content
· What do you already know about ubiquitination?
        o Proteins are ubiquitinated to mark them for degradation.

Consider Possibilities
· What other information is related to the question? Which information is most useful?
        o Eukaryotic cells selectively degrade proteins when they are no longer needed, by marking them.
        o The mark that cells use is the attachment of a ubiquitin molecule. Ubiquitin is a 76–amino-acid protein that can exist as an isolated molecule or in longer chains that are attached to other proteins.
        o The process of ubiquitination followed by degradation by the proteasome is called the ubiquitin–proteasome pathway. As the proteins are degraded, the ubiquitin chain itself is simply cleaved back into ubiquitin units that can then be reused.

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o If a certain protein is abnormally tagged with ubiquitin, then its levels will greatly decrease since it will be degraded in the proteasome.
 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 happen to levels of a protein that is ubiquitinated.
        o The question required you to take what you already know and apply it to this unfamiliar situation.
        o Did you remember that ubiquitin is a tag that marks a protein for destruction via the proteasome?