exam1-09for10 - C2006/F2402 10 Review Questions for Exam #1...

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C2006/F2402 ‘10 Review Questions for Exam #1 = Exam #1 of ‘09 Platelets are not whole cells – they are small fragments of larger cells. Platelets have no nucleus, but they have all the components normally found in the cytoplasm. Platelets are smooth and disc shaped (like mini-RBC) until a wound occurs – then the platelets are ‘activated’ – they bind to the ECM, change shape and trigger blood clotting. 1. Activation of platelets requires binding of the platelets to proteins in the ECM. A. Which of the following proteins in the platelets is most likely to bind directly to the ECM proteins? (transferrin) (transferrin receptor) (integrin) (ankyrin) (cadherin) (elastin) (dynein) (fibronectin) (bulletin) (tintin) (any of these). Explain in one sentence. B. Platelet activation is triggered by exposure to layers of ECM that are normally covered up. The protein that triggers activation is most likely to be (collagen) (an IF) (spectrin) (kinesin) (myosin) (tubulin) (actin) (poison). Explain in one sentence. C. Platelets that are not activated do not stick to each other, the ECM, or capillary walls. You would expect unactivated platelets to contain (desmosomes) (hemidesmosomes) (gap junctions) (adherens junctions) (lamin) (laminin) (nucleoli) (mitochondria) (none of these). Circle one or more, and explain briefly. 2. Serotonin is released by activated platelets, although its function in blood clotting is unknown. Most of the serotonin that is present inside platelets is found in intracellular storage organelles (storage vesicles). These organelles release serotonin by exocytosis. A. Consider a transmembrane (TM) protein in one of the storage organelles. The carboxyl end of the protein is in the lumen and the amino end is in the cytoplasm. Suppose the organelle releases serotonin to the outside of a platelet by exocytosis. Where should the TM protein be immediately after exocytosis? A-1. The TM protein should be found (in the platelet plasma membrane) (in a storage vesicle) (entirely in the cytoplasm of the platelet) (entirely outside the platelet). AND A-2. The carboxyl end of the protein should be (in the platelet cytoplasm) (in the lumen of a storage organelle) (on the extracellular side of the plasma membrane) (can’t predict). Draw or explain the position of the TM protein after exocytosis. B. When activation of platelets was first studied, fluorescent antibodies to actin and tubulin were not yet available. However the experimenters were able to check the state of the MTs and MFs in the platelets. B-1. How did they do it? They probably used (the light microscope) (the naked eye) (the EM) (either type of microscope) (any of these). No explanation required. B-2. Suppose that today, you wanted to examine the state of both the MTs and MFs in the platelets, using
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This note was uploaded on 02/21/2010 for the course ENG W2018 taught by Professor Niccolas during the Spring '10 term at Columbia.

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exam1-09for10 - C2006/F2402 10 Review Questions for Exam #1...

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