Hemoglobin and Iron Metabolism — MCQs

Q: How many Fe²⁺ atoms are present in one molecule of hemoglobin (Hb)?

Four Fe²⁺ atoms. ***Four Fe²⁺ atoms*** - A single molecule of **hemoglobin** is composed of **four globin chains**, each containing one **heme group**. - Each **heme group** in hemoglobin contains one central **ferrous iron (Fe²⁺) atom**, allowing for the binding of one oxygen molecule per heme group. *One Fe²⁺ atom* - This is incorrect because hemoglobin is a **tetramer**, meaning it has multiple subunits. - Only one heme group (and thus one Fe²⁺ atom) is present in **myoglobin**, which is a single polypeptide chain, not hemoglobin. *Two Fe²⁺ atoms* - This is incorrect as it does not account for the **tetrameric structure** of adult hemoglobin. - While some developmental forms of hemoglobin could be considered to have two alpha and two beta chains, each still has its own heme group. *Eight Fe²⁺ atoms* - This is incorrect as it would imply two Fe²⁺ atoms per heme group or multiple heme groups per globin chain. - The 1:1 ratio of heme group to Fe²⁺ atom and globin chain to heme group is fundamental to hemoglobin structure.

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Hemoglobin Structure and Function

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Oxygen Transport and Oxygen-Hemoglobin Dissociation Curve

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Hemoglobin Variants and Hemoglobinopathies

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Thalassemias

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Methemoglobin and Abnormal Hemoglobins

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Hemoglobin Synthesis

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Heme Synthesis and Porphyrias

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Iron Absorption and Transport

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Iron Storage and Recycling

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Disorders of Iron Metabolism

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Anemia: Biochemical Aspects

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Biochemistry of Hemostasis

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