I am having trouble answering the following question in my lab report. I have po
ID: 89947 • Letter: I
Question
I am having trouble answering the following question in my lab report. I have posted the question below as well as a copy of my lab assignment:
3. Write a paragraph describing the relative oxygen affinity of hemoglobin (or hemocyanin) under the various conditions that you tested.
Introduction: The circulatory system serves a number of functions in an animal, including distribution of nutrients and hormones to cells, removal of wastes, convective heat transfer, and maintenance of hydraulic pressure The most immediately critical function of the circulatory system for many animals is the delivery of oxygen to tissues to support aerobic metabolism (and removal of carbon dioxide). Very small animals (a few millimeters) with low metabolic rates may be able to acquire sufficient oxygen through diffusion but larger animals require a circulatory system. The circulatory system enables bulk flow of an oxygen containing fluid to the cells, where oxygen can diffuse into the cells and then into the mitochondria The amount of oxygen dissolved in a fluid is limited by its solubility in that fluid. Oxygen has a low solubility in water and an even lower solubility in salty solutions such as blood plasma (even lower if the blood is warm). Thus, many animals have evolved respiratory pigments that bind oxygen. These proteins increase the amount of oxygen that can be carried in a given volume of blood because oxygen can be carried bound to the protein and dissolved in the fluid. Four classes of respiratory pigments have appeared in the evolution of animals: hemoglobin, hemocyanin, hemerythrin, and chlorocruorin Binding of oxygen to the respiratory pigment at the lung or gill and release of oxygen at the tissues depends on the oxygen binding properties of the pigment. In other words, how readily oxygen binds to the pigment at a given partial pressure of oxygen determines how much oxygen binds to the pigment at the lung and how much oxygen is released in the systemic capillaries to diffuse into the cells. These proteins have evolved some interesting biophysical properties that make them particularly effective at accommodating the animal's need for oxygen transport in different metabolic states (rest, exercise, high altitude, etc.) In this lab, you will prepare samples of hemoglobin from red blood cells of a mammal (probably horse) or samples of hemocyanin from hemolymph of a horseshoe crab (Limulus sp.). You can then make measurements on these samples using a spectrophotometer in order to determine an oxygen-binding curve for the respiratory pigment. Once you have made an initial set of measurements to calculate an oxygen-binding curve for the blood of a large mammal at room temperature and a typical mammalian blood pH (7.4), you can investigate one of several variables, which may include body size, pH, PCO2, temperature, or the presence of organic phosphates. Some lab groups in each section may opt to investigate one of these variables in Limulus hemocyanin Your data will allow you to plot an "oxygen-binding curve" (also called a "saturation curve") for your respiratory pigment. Think about the shape of the oxygen-binding curve in the context of the "oxygen cascade" from the environment to the mitochondria and try to figure out what the shape of the curve tells us before we discuss it in lectureExplanation / Answer
The modulation of haemocyanin oxygen affinity was studied at 10°C in the blood of the intertidal prawn Palaemon elegans. On increasing the L-lactate concentation in dialysed blood from 0 to 9.1 mM, P50 decreased from 27 to 11 torr at pH 7.8. Undialysed blood exhibited a higher oxygen affinity than dialysed blood with the same lactate concentration indicating the presence of an unidentified factor which increased oxygen affinity. After dialysis both winter and summer blood exhibited the same intrinsic oxygen affinity and response to lactate. The response of oxygen affinity to lactate was exponential, low concentrations of lactate (0–5 mM) markedly increasing oxygen affinity. The lactate effect in dialysed blood expressed as logP50log[L-lactate was 0.56 at pH 7.8 and 0.63 at pH 7.4. The effect of lactate on oxygen affinity, P50, was similar in dialysed and whole blood. The effect of the unidentified factor (P50, between dialysed and undialysed blood) at the same lactate concentration was 13.1 and 15.1 torr at pH 7.8 in winter and summer blood, respectively. At pH 7.4 the P50 was 38 torr for both summer and winter blood. Differences in oxygen affinity between blood collected in summer and winte cloud be explained by difference in blood lactate concentrations.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.