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Analysis of a Cell Surface Receptor


1. For Part A, please explain in detail the results in Data Analysis and why they turned out as they did?
2. For Part B, please explain in detail the results in Data Analysis and why they turned out as they did?
3. One of the simple sugars (galactose or mannose) used in this exercise should have inhibited Con A-peroxidase binding to cheek epithelial cells and the Con A-induced hemoagglutination reaction. Name this sugar and describe the mechanism by which it inhibits these effects?
4. Describe the mechanism responsible for the Con-A induced hemoagglutinating reaction?
5. Most membrane proteins including the Con-A receptor can be solubilized by treating cell membranes with a non-ionic detergent such as Triton X 100. You are given such a soluble preparation of erythrocyte proteins. Describe a single procedure that could be used to isolate the Con A Receptor from this preparation?
6. What would be a good title for the the experiment preformed?


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Title: Analysis of the ConA Cell-Surface Receptor

Part A: Tube 1 contains only buffer. There is no enzyme (peroxidase). Therefore, this tube acts as your negative control. Any color we see in this tube is meaningless. It is merely "background" color reaction. Tube 2 is your positive control. We've added the enzyme to the reaction, but have not added any "test" sugar for inhibition. This tube should give a strong positive reaction. Tubes 3 and 4 test for the inhibitory effect of galactose and mannose, respectively.

Now, if we look at the results, we see that Tube 1 did not stain purple at all, just a background green and red. This is the negative result indicating no peroxidase reaction at all. Tube 2 is our positive reaction tube. And clearly, we can see a very dark band of purple staining along the plasma membrane. This is showing us, not only a positive reaction, but the location of ConA receptor, i.e. the plasma membrane.

Tube 3 shows a faint purple that surrounds the cells. Therefore, we still have a positive reaction, but not as ...