Botox case study.docx - Botched Botox Case Study Part I 1 Why are endocytosis and exocytosis considered active transport mechanisms if they do not

Botox case study.docx - Botched Botox Case Study Part I 1...

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Botched Botox Case Study Part I 1. Why are endocytosis and exocytosis considered active transport mechanisms if they do not necessarily move molecules against a concentration gradient? - These mechanisms are considered active transport because they require energy for the membrane to change to accept/ eject vesicles. Energy is also needed to move the vesicles to and away from the membrane. 2. What is clathrin and what is its role in receptor-mediated endocytosis? - Clathrin is a protein that forms a lattice around the vesicle. It surrounds the evaginating membrane. 3. Compare and contrast receptor-mediated endocytosis with phagocytosis and pinocytosis. - Receptors in receptor-mediated endocytosis require a specific stimulus for the molecule to be accepted into the membrane. During phagocytosis, macromolecules are non- specifically engulfed by the cell. During pinocytosis, fluid is non-specifically engulfed by the cell. 4. What are some other examples of proteins secreted by exocytosis that are essential for cell and tissue function? - Exocytosis secretes necessary molecules such as neurotransmitters, enzymes, hormones and antibodies. 5. From memory, sketch a section of the phospholipid bilayer of an axon terminal and diagram how neurotransmitter-containing vesicles secrete protein in the absence of BoNT via exocytosis. On the drawing, add transmembrane receptor proteins that BoNT binds to and diagram receptor- mediated endocytosis of the receptor bound to BoNT and how it can influence exocytosis.

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