After a search of nucleotide sequence databases, researchers identified an IRE in the 5c untranslated region of a gene encoding aconitase, an enzyme involved in the Krebs cycle.

Which of the following pieces of experimental evidence best supports the claim that the synthesis of aconitase is controlled by a mechanism similar to ferritin regulation?

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Full Question:

After a search of nucleotide sequence databases, researchers identified an IRE in the 5' untranslated region of a gene encoding aconitase, an enzyme involved in the Krebs cycle. Which of the following pieces of experimental evidence best supports the claim that the synthesis of aconitase is controlled by a mechanism similar to ferritin regulation?

(A) IRP binds to aconitase mRNA in the presence of iron.

(B) The relative amount of aconitase protein increases in the presence of high levels of iron. NADH and FADH2, increase in the presence of high levels of iron.

(C) Oxygen consumption by cells increases.

(D) The levels of reduced electron carriers.

Answer:

The relative amount of aconitase protein increases in the presence of high levels of iron. NADH and FADH2, increase in the presence of high levels of iron which best support the claims.

Option B

Explanation:

Iron induced toxicity deals with the excess intracellular iron. The excess amount of iron are binded by Ferritin that is an intracellular iron storage. The cells are protected from the iron induced toxicity by the presence of ferritin.

When the iron levels are high, the intracellular iron binds to the IRP. The iron-IRP dislocates from IRE releasing ribosomes to proceed with the translation of ferritin mRNA. When iron levels are low, a repressor of translation, iron response protein (IRP), binds to an iron response element (IRE), which is a stem-loop structure near the 5' end of ferritin mRNA.