Micro - Nucleus, ER, and Golgi
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- what is the nuclear envelope?
- it encloses DNA and defines the nuclear compartment
- what does the inner nuclear membrane have?
- it contains specific proteins that act as binding sites for the nuclear lamina
- 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 - what are the nuclear pores composed of?
- the nuclear pore complex, which is composed of ~100 diff proteins in octagonal symmetry
- what does the nulcear pore complex allow to pass freely?
- small, water-soluble molecules
- 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 - what is the purpose of the nuclear lamina?
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it gives shape and stability to the nuclear envelope
also holds chromatin - what kind of proteins are in the nuclear lamina?
- in mammals, lamins (intermediate filaments) in a distinctive square lattice
- 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 - what is the nucleolus?
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site of rRNA sytensis and ribosome assembly
consists largely of RNA and proteins; - how does the nucleolus stain on H&E?
- basophilic
- is the nucleolus membrane bound?
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no, not mbn bound
there are no mbn bound organelles within the nucleus - what is the nucleolar organizer region?
- DNA from several chromosomes; code for rRNA
- what happens to the ribosomal subunits?
- synthesized in the nucleolus, leave via nuclear pores, assembled in cytoplasm
- how many nucleoli does a cell have?
- varies; 2-3 in active cells
- what is chromatin?
- complex of DNA and proteins
- how does chromatin stain?
- basophilic
- what is heterochromatin and how does it stain?
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inactive chromatin
basophilic, and electron dense - what is euchromatin and how does it stain?
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active chromatin
lightly staining, electron light - 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 - what is the smooth endoplasmic reticulum?
- tubular, and continuous with RER
- where is smooth ER found?
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cells for lipid synthesis and metabolism
cells for detox of toxic materials - what is the sarcoplasmic reticulum?
- specialized smooth ER in striated muscle cells
- what does the Golgi apparatus do?
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receives proteins from the ER and dispatches then
4-6 curved membranous golgi cisternae - 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 - how are things transported b/w the cisternae of the golgi?
- by coatamer-coated vesicles
- how does the golgi stain?
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stains poorly;
pale area near nucleus - what is the default method of protein secretion?
- constitutive secretory pathway - protein enters RER lumen, then to golgi, then immediately secreted or inserted into cell mbn
- what is the regulated secretory pathway?
- signal -> protein diverted to organlle or packaged for secretion.