Mechanical Engineering Exam Help

Mechanical Engineering Exam Help

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Problems 1.A company has begun to market a fibronectin-coated cell culture dish. You are considering the purchase of culture 2. dishes for your in vitro study of a cell type for which you have relatively little information. You have been able to 3. determine, however, that the cell has the 61 integrin. Would you expect there to be any benefit to using the fibronectin-coated dish? Explain .

4.Another company provides you with their new culture dish (not the fibronectincoated dish above). You culture 5.fibroblasts on conventional dishes (without any additional protein coating) and on the new dishes. You find that 6.the cells stick to the conventional dish but not to the new dish. Explain these findings.

7. A transgenic strain of mice is missing a particular type of cell adhesion molecule. The pups survive only a few days 8. After birth, but you are able to make the following dermis is abnormal and does not heal by

observations. The

9. contraction as it does normally. The epidermis is normal and regenerates normally when injured. a)What is the likely missing cell adhesion molecule? Explain b)Name 2 other tissues that you would expect to be abnormal and 2 other tissues that you would anticipate would be normal? Explain.

Solutions 1.The ligand for the 61 integrin is laminin, not fibronectin. Therefore, one might not 2. expect much binding of the cells to the fibronectin-coated dish 3.The cells are attaching to the conventional dishes, even though the dishes are not pre-coated with an adhesion protein, because the cells are synthesizing their own adhesion proteins, which are becoming.

4. adsorbed to the dish and subsequently serve as binding sites for the cells; the cells have integrins to the adhesion proteins that they make. The new dishes may not have a chemical composition that allows for adsorption of the adhesion proteins produced by the cells.

5. One explanation for the inability of the dermis to heal by contraction like it normally does is that the 6. fibroblasts are not able to bind to the matrix molecules (viz., collagen). The likely missing cell adhesion molecule is an integrin for fibronectin (or collagen).

Tissues that you would expect to be abnormal would be connective tissues requiring cell adhesion to fibronectin and collagen, and 2) tissues that would likely heal normally would be tissues in which cells bind to basement membrane (i.e., in which laminin is the ligand).