Hemoglobin & Spectrophotometry
Briefly, the lab with the worm blood is quite easy if you remember,
we were looking at two distinct things.
1. The difference between oxygenated and deoxygenated blood
2. The difference between earthworm (P. Annelida) blood and mouse (P.
Chordata) blood
1. Now, with those in mind, you need to understand what is meant by allostery. Allostery is a concept that applies to chemicals (usually proteins or enzymes) that change their shape (i.e., spatial configuration) when another chemical binds to it. In this lab we were looking at allosteric changes of hemoglobin a respiratory pigment protein. Hemoglobin is a protein that binds molecular oxygen to it. This protein has one shape when it is unbound (i.e., contains no oxygen), and 2 other forms when oxygen is bound to it. This is a total of 3 forms. Hemoglobin has 4 chains 2 alpha chains and 2 beta chains. When it is deoxygenated, the hemoglobin is all squished up. (The first form) Then, one molecular oxygen binds to the alpha chains. This induces a change in the hemoglobin shape. (The second form). After binding to the alpha chains the hemoglobin protein further changes shape so that the beta chains can now accept oxygen. (The third shape) So, on a graph you will see a one-humped curve, which represents deoxygenated blood. (E.g., only one shape present) when placed in a spectrophotometer. Next, you will see a 2-humped curve that represents oxygenated blood. The first hump represents when the alpha chains have oxygen bound to it and the second hump represents when the beta chains accepts oxygen.
2. Now, worms have hemoglobin that freely floats around in their blood.
However, mice have specialized cells called erythrocytes (a.k.a., RBCs)
These RBCs are able to have in many, many times the amount of hemoglobin
in their blood than do worms. As such on a graph that has both worm
and mouse blood, you will see mice was higher up on the scale above the
worms because there is more hemoglobin present to bind more oxygen than
occurs in a worm.