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40 Cards in this Set
- Front
- Back
what are the two major types of endocytosis?
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pinocytosis and phagocytosis
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what characterizes pinocytosis and what it the nickname often given to this process?
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characterized by uptake of fluids, macromolecules, and small particles; cell drinking
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what characterizes phagocytosis and what it the nickname often given to this process?
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characterized by ingestion of large particles (>.5 microns); cell eating
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which, phago- or pinocytosis is most heavily reliant on receptor-mediated uptake?
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phagocytosis
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what is the name for the process in which a cell targets its own organelles for degradation by fusion with the endosomal/lysosomal dept?
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autophagy
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which of the two methods of endocytosis is most commonly used as a synonym for endocytosis?
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pinocytosis
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what is the name for the molecules that most commonly form the coating in a coated vesicle? are the found on the inside or outside of the cell?
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clathrin; inside
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after a clathrin pit has been uncoated, what is contained in the vesicle?
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membrane, receptors, ligands (target molecules)
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are early endosomes characterized by high or low pH? for what early endosomal function does this exceptional pH allow?
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low pH; dissociation of receptors and ligands
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true or false: when vesicles reach early endosome, membrane is recycled but receptors are not.
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false. All recyclable materials are recycled.
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in which compartment are ligands broken down by acid hydrolases?
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late endosome
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in which compartment is terminal digestion of ligands performed?
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lysosome
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what is the name for lysosomes filled with undigestible material? what is the name for this material which stains a brownish color?
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residual bodies; lipofuscin
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how are endosomal and lysosomal compartments normally visualized under a light microscope? why?
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via histochemical or immunocytochemical techniques; with a normal stain, the compartments are indistiguishable. their protein makeups distinguish them
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what are the two classes of 'professional' phagocytes?
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neutrophils and macrophages
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what is the name for the process by which the immune system coats invading bacteria with antibodies or complement?
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opsonization
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opsonins are engulfed by phagocytes. the resulting body is called what?
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a phagosome
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true or false. endosomes and lysosomes have identical pH's.
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false. The pH of the lysosome is lower than the late endosome which is lower than the early endosome.
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which, pinocytosis or phagocytosis, is considered to be a constitutive process?
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pinocytosis
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what proteins, other than clathrin, commonly coats the pits that lead to endocytosis?
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caveoli
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the binding of what to the intracellular domain of the receptor triggers the aggregation of clathrin molecules?
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adaptin (AP-2)
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during endocytosis, what molecule is responsible for making sure the entire vesicle enters the cell (like a purse string)?
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dynamin
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what is the term used to describe 3 molecules of clathrin light and heavy chains that form a basket?
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triskelion
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at what point is coated vesicle stripped of clathrin coat?
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immediately following complete invagination of vesicle.
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which is more selective: clathrin or caveoli pits?
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clathrin
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what molecule is requires for a coated vesicle to uncoat?
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ATP
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are adaptins unique to each receptor?
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no, they can bind to several different receptors
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how is the early endosome tranferred to the late endosome?
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via microtubule network/motor proteins
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among the early and late endosome and lysosome, which have ATPases? what purpose does the ATPase serve in these compartments?
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late endosome and lysosome; makes the compartments more acidic.
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what is the necessary working environment for acid hydrolases?
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acidic environment. will not work in physiological pH
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what aspect of lysosomes and late endosomes is crucial in keeping these compartments intact?
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glycosylation
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because they are clustered near the RER, which confirms their identity as secretory vesicles
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in this picture, how would one know that the dark circles are secretory vesicles and not lysosomes?
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what happens to actin skeleton when phagocytes want to engulf opsonin?
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it reorganizes to accomodate for phagocytosis
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what morphological feature do phagocytes use to engulf opsonins?
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pseudopodia
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when a phagosome and a lysosome fuse together, the resulting body is called what?
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phagolysosome
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several phagocytes fused together to accomodate a large opsonin, such as a bacterium or cell
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what is a possible explanation for the large, multinucleated cell seen in this stain?
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which organelle is responsible for invagination of dead organelles in autophagy?
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SER
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what is the size limit for pinocytosis?
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150nm
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what is the minimum size for phagocytosis
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250nm
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what is the pH of the early endosome? the late endosome? the lysosome?
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6; 5.5-6; 5
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