Which globin chains compose hemoglobin A1?

Which globin chains compose hemoglobin A1?

• A. Two alpha chains and two beta chains
• B. Two alpha chains and two delta chains
• C. Two alpha chains and two gamma chains
• D. Two beta chains and two delta chains

Answer: (A)

Hemoglobin A1 is composed of two alpha globin chains and two beta globin chains, forming an α2β2 tetramer. This is the dominant adult hemoglobin, optimized for oxygen transport in most life stages. In contrast, HbA2 is the form with two alpha and two delta chains (α2δ2), and HbF is the fetal form with two alpha and two gamma chains (α2γ2). The alpha chains are encoded on chromosome 16 and the beta chain cluster on chromosome 11, which is why adults typically have two alpha and two beta chains in HbA1 while other forms vary by the non-alpha component.

Hemoglobin A1 is composed of two alpha globin chains and two beta globin chains, forming an α2β2 tetramer. This is the dominant adult hemoglobin, optimized for oxygen transport in most life stages. In contrast, HbA2 is the form with two alpha and two delta chains (α2δ2), and HbF is the fetal form with two alpha and two gamma chains (α2γ2). The alpha chains are encoded on chromosome 16 and the beta chain cluster on chromosome 11, which is why adults typically have two alpha and two beta chains in HbA1 while other forms vary by the non-alpha component.