Identify a respiratory pigment, and then describe its structure and how this relates to its function. What will be an ideal response?
Hemoglobin, hemocyanin and myoglobin are all respiratory pigments, but hemoglobin is the
most common respiratory pigment in vertebrates. Hemoglobin consists of four polypeptide
chains (the globin portion), and attached to each chain is an iron-porphyrin (heme). An iron
atom is attached to each heme, and one O2 molecule attaches to each iron. As a result, each
molecule of hemoglobin has the potential to bind four molecules of O2.The extent to which
hemoglobin binds O2 depends on several factors, one of which is the partial pressure of O2.
Where the PO2 is high (e.g., in the pulmonary capillaries), hemoglobin “loads up” with
oxygen, and where the PO2 is low (e.g., deep in the tissues far from the lungs), hemoglobin
“unloads” its O2. In addition, where the PCO2 is high (e.g., deep in the tissues), the CO2
reacts with water to form bicarbonate and hydrogen ions. The resulting decrease in pH causes
hemoglobin to unload its O2. As a result, hemoglobin doesn’t unload its O2 until the
hemoglobin is close to rapidly respiring cells.
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Lactic acid bacteria such as Streptococcus are obligate fermenters that can exist in an aerobic environment due to their use of catalase to mitigate the presence of oxygen
Indicate whether this statement is true or false.
In humans, the embryonic development of a fourchambered
heart and the limb buds is present during which week? a. third b. fourth c. fifth d. sixth e. seventh
The "Age of Fishes" is an informal name for which time period?
a. Silurian period b. Permian period
c. Devonian period d. Ordovician period e. Carboniferous period
The layer where organisms can exist on the surface of the earth is the
(a). biosphere. (b). ecosystem. (c). population. (d). homeostasis. (e). community.