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29 Cards in this Set
- Front
- Back
what is the nuclear envelope?
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it encloses DNA and defines the nuclear compartment
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what does the inner nuclear membrane have?
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it contains specific proteins that act as binding sites for the nuclear lamina
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what does the outer nuclear membrane have?
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it is studded with ribosomes that make proteins transported into perinuclear cisterna
it is continuous with the inner nuclear mbn |
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what are the nuclear pores composed of?
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the nuclear pore complex, which is composed of ~100 diff proteins in octagonal symmetry
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what does the nulcear pore complex allow to pass freely?
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small, water-soluble molecules
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what is the nuclear lamina?
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meshwork of intermediate filaments that line the inner nuclear membrane
it is anchored to nuclear pores and the inner nuclear mbn |
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what is the purpose of the nuclear lamina?
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it gives shape and stability to the nuclear envelope
also holds chromatin |
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what kind of proteins are in the nuclear lamina?
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in mammals, lamins (intermediate filaments) in a distinctive square lattice
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what happens to the nucleus during mitosis?
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nuclear lamina depolymerizes, caused by phosphorylation of nuclear lamins
nuclear envelope broken up into mbn vesicles dephosphorylation of lamins causes reassembly of lamina |
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what is the nucleolus?
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site of rRNA sytensis and ribosome assembly
consists largely of RNA and proteins; |
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how does the nucleolus stain on H&E?
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basophilic
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is the nucleolus membrane bound?
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no, not mbn bound
there are no mbn bound organelles within the nucleus |
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what is the nucleolar organizer region?
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DNA from several chromosomes; code for rRNA
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what happens to the ribosomal subunits?
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synthesized in the nucleolus, leave via nuclear pores, assembled in cytoplasm
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how many nucleoli does a cell have?
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varies; 2-3 in active cells
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what is chromatin?
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complex of DNA and proteins
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how does chromatin stain?
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basophilic
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what is heterochromatin and how does it stain?
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inactive chromatin
basophilic, and electron dense |
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what is euchromatin and how does it stain?
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active chromatin
lightly staining, electron light |
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what is the rough endoplasmic reticulum?
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organelle with polyribosomes attached to cytosolic surface of mbn
has integral proteins to recognize and bind ribosomes |
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what is the smooth endoplasmic reticulum?
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tubular, and continuous with RER
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where is smooth ER found?
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cells for lipid synthesis and metabolism
cells for detox of toxic materials |
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what is the sarcoplasmic reticulum?
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specialized smooth ER in striated muscle cells
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what does the Golgi apparatus do?
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receives proteins from the ER and dispatches then
4-6 curved membranous golgi cisternae |
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what are the sides of the golgi?
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on each stack:
cis face - entry face, curved trans face - exit face overall: cis Golgi network - proteins and lipids enter in transport vesicles (w/ CotII); from ER trans Golgi network - exit in transport vesicles |
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how are things transported b/w the cisternae of the golgi?
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by coatamer-coated vesicles
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how does the golgi stain?
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stains poorly;
pale area near nucleus |
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what is the default method of protein secretion?
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constitutive secretory pathway - protein enters RER lumen, then to golgi, then immediately secreted or inserted into cell mbn
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what is the regulated secretory pathway?
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signal -> protein diverted to organlle or packaged for secretion.
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