please answer all the questions Thank you DEL Exercise 9-55 3. You wish to deter

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please answer all the questions
Thank you

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

Q.3 a) From above given results, distribution of 4 principal phospholipids is as follows.

         Exoplasmic face = Phosphotidyl choline, sphingomyline

        Cytosolic face = Phosphotidyl –ethanolamine, phosphotidyl amine.

     For plasma membrane Cytosolic face is different from exoplasmic face. There is asymmetrical distribution of phospholipids on both sides of plasma membrane. After synthesis of phospholipids, in the golgi complex asymmetrical distribution of phospholipids occur with the help of transporters flipase and floppase. These are responsible for asymmetric distribution of phospholipids in plasma membrane. Some phospholipids show partial asymmetry and some shows absolute asymmetry.

For example = some phospholipids like phosphotidyl choline 90% found on exoplasmic side but 10% found may found on cytosolic side. This is partial asymmetry.

Some phospholipids like sphingomyeline, sphingoglycolipids strictly found on exoplasmic face. Never on cytosolic face. This is absolute asymmetry.

That’s why plasma membrane have cytosolic and exoplasmic faces different from each other. Due to different membrane lipid distribution.

Q.3b) Mature mammalian RBC is best model to study plasma membrane. It do not contain any other cell organelle. So other membrane fractions do not interfere in homogenate.so RBC used for experiment.

Q.4) Inside out membrane vesicle and right side out membrane vesicle can be separated from each other by column chromatography using lectin column. Lectin are carbohydrate binding proteins. Glycolipid are always present on exoplasmic face of plasma membrane. Glycolipids have carbohydrate moieties. These carbohydrate moieties can bind with lectin.

So when homogenate conaining Inside out and Right side out membrane vesicles is passed through lectin column, right side out vesicles containing glycolipid on outer side will bind with lectin, they will retain inside column and inside out will not bind with lectin and they will get eluted. By this process we can separate inside out vesicles. Right side out vesicle retained in the column can be eluted by secondary elution. This is how we can seperate inside out and right side out vesicle of plasma membrane using lectin column based chromatography.

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