BIS 104 PQ 7 ans 2011

BIS 104 PQ 7 ans 2011 - provides initial trigger for...

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BIS 104 PQ 7 ans 2011 7. For each of the items listed below describe i) its composition and location, and ii) its major function(s). The first one is done for you as an example of an appropriate answer to this type of question. A) NUCLEAR PORE COMPLEX (NPC) i) Located in the double nuclear membrane of eukaryotic cells; there are approximately 1,000 per nucleus and they are composed of an octagonal complex of approximately 20 different proteins. ii) The NPC in conjunction with carrier proteins such as exportins and importins, controls the entry and exit of molecules that pass between the cytosol and the nucleoplasm. B. MITOCHONDRIA i) Membrane bound organelle found spread throughout the cytoplasm of eukaryotic cells. Composed of an inner and outer lipid bilayer membrane and an inner matrix containing proteins and circular mtDNA. ii) Generates ATP by oxidative phosphorylation; sequesters free ionic Ca++;
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Unformatted text preview: provides initial trigger for apoptosis. C. SMOOTH ENDOPLASMIC RETICULUM i) An extension of the outer bilayer of the nuclear envelope, it is located between the nucleus and the ERGIC. It is composed of a network of tubular lipid bilayer compartments and enzymes. ii) It is the site of lipid and sterol synthesis and the detoxification (enzymatic oxidation) of xenobiotics. Also, serves as a storage site for free Ca++. D. MICROTUBULES (MTs) i) Located in the cytoplasm as part of the cytoskeleton and in the nucleus of mitotic cells as part of the mitotic spindle. Composed of polymerized proto-filaments of alpha and beta tubulin proteins. ii) In cytoplasm, serves to establish and maintain cell shape. Provides polar tracks for guiding transport of intracellular cargos. In the nucleus, captures chromosomes for mitosis and is involved in orienting the spindle apparatus....
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