You are studying a disease caused by insufficient levels of a specific peptide hormone, and characterize mutations in several genes that can lead to the disease. Your startup company can only afford to pursue one gene product as a possible therapy. Which would you choose?

Question

A.  Gene A -- a transcription factor.
B.  Gene B -- an enzyme that activates the hormone by cleaving its inactive precursor.
C.  Gene C -- the hormone itself.
D.  Gene D -- a kinase that acts downstream of the hormone.

Clarify Question
What is the key concept addressed by the question?
What type of thinking is required?

Gather Content
What do you already know about hormones? What other information is related to the question?

Choose Answer
Given what you now know, what information 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

C.  Gene C -- the hormone itself.

Clarify Question
What is the key concept addressed by the question?
        · What gene is best for drug targeting?
What type of thinking is required?
            o This is an evaluate question because you have to consider each potential gene to pursue as a potential therapy for hormonal deficiency and consider its benefits and drawbacks.

Gather Content
What do you already know about hormones? What other information is related to the question?
        · Hormones deliver their signals through the bloodstream. As blood travels to all tissues, they bind to either cell-surface or intracellular receptors to initiate changes in the cell.Hormones can be regulated at many levels. Genes for hormones can be regulated by transcription factors. Precursor hormone molecules are modified by enzymes to convert them into hormones. In addition, regulation can occur downstream of the hormone in a cellular pathway. While modifying all these regulatory methods could help with hormone deficiencies, supplying patients with more of the hormone itself is the most efficient means of therapy.

Choose Answer
Given what you now know, what information is most likely to produce the correct answer?
        · Peptide hormones are an attractive drug target since they are easily synthesized and become bioavailable as soon as they enter the bloodstream. Transcription factors are generally difficult to target with drugs. The enzyme is likely to be large and intracellular. The kinase is intracellular and likely functions in many other tissues, so targeting it may produce negative side-effects.

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?
          · Answering this question correctly depended upon considering different levels of regulation of hormones. If you got the answer correct, great! If not, which answer did you choose? Did you choose transcription factor since you knew that transcription is the first step in turning a peptide hormone gene into a protein? That is true, but, given a limited budget, the most direct and effective method would be to simply supply the patient with the hormone itself.