Question

a. Why does hemoglobin bind so much more readily to a second and third molecule of oxygen than to the first? b. why is the deoxyhemoglobin and the oxyhemoglobin so intensely colored? c. How is carbon dioxide really removed from the cells (it does not bind to the hemoglobin)?

Answer 1

a. Hemoglobin is a protein molecule found in erythrcytes (red blood cells). Hemoglobin binds easily to second and third oxygen molecule than the first molecule, because when the hemoglobin molecule it chages its shape or confromation when it binds to oxygen. Compare to the first oxygen molecule, it much more difficult with the fourth oxygen molecule.

b. Partially or fully unloaded hemoglobin is called deoxyhemoglobin (deoxy-Hb) which is dark blue to purplish color as in venous blood.The loaded pigment is called oxyhemoglobin(oxy-Hb) is a brilliant red color as in arterial blood. The difference in colour is due to the electronic state of the iron ion (ferrous vs ferric), which in turn influences the electronic transitions of porphyrin and hence its optical characteristics.

c. CCO2 diffuses into the blood plasma and then into the RBC, which reacts with water

H2O + CO2 ?H2CO3

H2CO3 ? dissociates to form H+ ions and HCO3- ions

Negatively charged HCO3- ions diffuse from the cytoplasm of red blood cells to the plasma, increasing the pH of the blood. H+ ions, then react with haemoglobin charged with oxygen, releasing it to reduce the acidity of the blood.

Carbon dioxide is mainly removed from the cell to reduce its concentration and is transported to the lungs were its concentration get reduced.

It will be easily removed from the body once they become dissociated from one another.