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Biochemistry

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Purines, Pyrimidines and Nucleic Acid Metabolism

Question
9 out of 59
 

Which of the following is most likely to be true in hemochromatosis,?



A The mRNA for the transferrin receptor (TfR) is stabilized by the binding of IRPs to 3′ stem-loop structures known as IREs.

B The mRNA for the TfR is not bound by IRPs, and is rapidly degraded.

C The mRNA for apoferritin is not bound by IRPs at its 5′ stem-loop IRE, and is translated.

D Both B and C

Ans. D Both B and C

a. When iron levels in the body are high, as is seen with hemochromatosis, there is increased synthesis of the iron-storage molecule, apoferritin, and decreased synthesis of the transferrin receptor (TfR) that mediates iron uptake by cells.

b. These effects are the result of trans-acting iron regulatory proteins (IRPs) binding iron rather than binding cis-acting iron-responsive elements (IREs), resulting in degradation of the mRNA for TfR, and increased translation of the mRNA for apoferritin.

Purines, Pyrimidines and Nucleic Acid Metabolism Flashcard List

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