Under physiological condition, oxygen is binding to deoxyhemoglobin and deoxymyoglobin, the binding curve and its pH dependence, respectively, are:a)Sigmoidal and pH dependent; hyperbolic and pH independent.b)Hyperbolic and pH independent; Sigmoidal and pH dependent.c)Sigmoidal and pH independent; hyperbolic and pH independent.d)Hyperbolic and pH dependent; Sigmoidal and pH dependent.Correct answer is option 'A'. Can you explain this answer?

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Answer

Binding of Oxygen to Hemoglobin and Myoglobin

Under physiological conditions, oxygen binds to deoxyhemoglobin (Hb) and deoxymyoglobin (Mb) for transport and storage, respectively. Binding of oxygen to Hb and Mb is influenced by several factors such as pH, temperature, and partial pressure of oxygen (pO2).

Oxygen Binding Curve

The oxygen binding curve for Hb is sigmoidal, which means that the binding of the first oxygen molecule increases the affinity of the remaining binding sites for oxygen. This is known as cooperative binding. The curve for Mb is hyperbolic, which means that the binding of oxygen to one site does not influence the binding of oxygen to the remaining sites.

The reason for the difference in the binding curves is because Hb is a tetramer with four subunits, whereas Mb is a monomer with only one subunit. The cooperative binding of Hb allows for efficient oxygen transport in the blood, whereas the hyperbolic binding of Mb allows for efficient oxygen storage in muscle tissue.

pH Dependence

The binding of oxygen to Hb and Mb is also influenced by pH. As pH decreases (becomes more acidic), the affinity of Hb and Mb for oxygen decreases. This is known as the Bohr effect. The Bohr effect is important for oxygen transport in the blood because it allows for the release of oxygen in tissues with high metabolic rates, which produce more acid and lower the pH.

The pH dependence of oxygen binding is more pronounced in Mb than in Hb because Mb is found in muscle tissue, which has a more variable pH than blood.

Conclusion

Under physiological conditions, the oxygen binding curve for Hb is sigmoidal and the binding curve for Mb is hyperbolic. The binding of oxygen to Hb and Mb is influenced by pH, with the affinity for oxygen decreasing as pH decreases. This allows for efficient oxygen transport and storage in the body.

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