Lecture 8
Animal of the day: the silk worm
Adaptation that increases the oxygen carrying capacity of blood or hemolymph
· This is a specific kind of protein that binds oxygen and thus increases the amount of oxygen the blood or hemolymph can carry. Oxygen does dissolve in the hemolymph but in many animals it is also carried by this special kind of protein
o Humans have hemoglobin. A tetramere each unit containing a heme group. Heme group has a metal ion iron, oxygen binds to iron.
o Oxygenated hemoglobin has a red color, unbound hemoglobin has a bluish color.
o Mammalian hemoglobin’s are tetrameric, but it is not true that all hemoglobin’s are tetrameric
· In the animal kingdom there are 4 types of oxygen carrying proteins
· Hemoglobin is found in all vertebrates and some invertebrates
· Hemoglobin in birds is also tetrameric
· Hemoglobin oxygen binding curve/ oxygen disassociation curve
o As partial pressure of oxygen increases so does % saturated hemoglobin
o There is cooperatively seen due to the sigmoidal shape of the curve
§ When one oxygen binds less energy is required to bind the next oxygen, it gets easier and easier to load the rest of the sites as oxygen binds.
· Momeric hemoglobin, like that in toadfish
o There is a hyperbola not a sigmoid curve.
§ When carbon dioxide is present then the binding affinity drops for oxygen… this is a monomeric hemoglobin therefore it has no sigmodial curve… its hyperbolic so present of co2 will make it look like carbon monoxide poising to humans
· Bhor affect…affinity of oxygen is higher when the ph is high and when the ph is lower the oxygen binding is lower.
o A shift towards the right when the pH is lower. This means the affinity has dropped.
§ This helps oxygen affinity drop near the tissues, because there is higher concentration of Pco2 which means lower ph.
o 2,3 diphosphoglyceral . decreases oxygen binding affinity… increases the probablility that oxygen diassociates.
· Members of the camel family have higher oxygen binding affinity for hemoglobin.
o This is a ture adaptation. Species specific , not gained by acclimation
· Varies with body size.. hemoglobin in an elephant has a higher binding affinity than a mouse
· Amount of hemoglobin in the blood of an animal can change to a respose to environmental conditions. Acclimatization
