This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
2, 3 DPG causes ? 
Select and explain. 
A. Decrease binding of O2 and hemoglobin, B. Increased acidity in RBC, C. Decreased acidity in RBC, D. Lysis of RBC
A: Decrease binding of O2 and hemoglobin
Answer: A: Decrease binding of O2 and hemoglobin 
Explanation: Ans. is 'a' i.e., Decrease binding of O2 and hemoglobinDPG is an optional by-product of the glycolytic pathway . DPG binds with deoxygenated hemoglobin but not with oxygenated hemoglobin . Therefore raised DPG concentration releases oxygen from oxyhemoglobin by shifting thefollowing reversible reaction to the right : -HbO, + DPGHb - DPG + 02One molecule of DPG binds with one mole of deoxyhemoglobin.That is why in the presence of raised DPG concentration, less oxygen can combine with hemoglobin at a given PO2. Hence an increase in DPG concentration shifts the oxygen-hemoglobin dissociation curve to the right. Thus 2,3 DPG causes delivery (unloading) of O2 to the tissues.