DEL Exercise 9-55 3. You wish to determine ine the distribution of phospholipids
ID: 210538 • Letter: D
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DEL Exercise 9-55 3. You wish to determine ine the distribution of phospholipids in the plasma membrane. You use of right-side out and inside out red that reacts with primary amino groups and two different phospholipases marized below (+ = reacted; -= did not react). blood cells. You treat the cells with SITS, a fluorescent dye . The results are sum- SphingolipaseSea snake venom Right side Inside out Right side Inside out Right side Inside out SITS out out out Phosphatidycholine Phosphatidyl-ethanolamine Sphingomyelin Phosphatidylamine From these results deduce the distribution of the four principal phospholipids in membranes. Is the cytosolic face of the plasma membrane the same as the exoplasmic face? a. b. Why did you use red blood cells for this experiment? Assume that you lysed red blood cells and let the membranes reform knowing that some will reform inside-out. How can you separate the right-side out membranes from the inside-out membranes? 4. 5. Using PubMed, find one current example of the use of lectins in research on mammalian cells Briefly describe the research and give the proper citation for the article.Explanation / Answer
3.a) No,
When we treated the right side out and inside out vesicles with SITS dye and 2 phospholipases(sphingolipase and snake venom),they reacted differently with the phospholipids of membrane.This difference tell us that the composition of both leaflets is not same.
The reaction of inside out vesicles tell the composition of inner leaflet or cytoplasmic face of membrane.So it can be concluded that inner leaflet is rich in phosphatidylethanolamine and phosphatidylamine while exoplasmic face is rich in sphingolipids and phosphotidylcholine.
3.b).Generally RBCs are used to prepare inside out vesicles and right side out vesicles because more is known about the plasma membrane of RBCs than any other eukaryotic membrane.RBCs are available in large number and relatively uncontaiminated by other cells.They also do not have nucleus or internal organ,plasma membrane is the only membrane so can be isolated without contaimination by internal membranes.
4. The inside out vesicles can be purified by using flourescent dye SITS which can binds with membrane phospholipids specific to inner leaflet.
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