Exam 3 -- CB Flashcards
(57 cards)
cytoskeleton
maintains cell architecture; allows movement of cells, and transport inside cells; three types: actin filaments, microtubules, intermediate filaments
Intermediate filaments
withstand mechanical stress; connects cells into tissues; allow cells to stretch without tearing; provide structure to the nucleus in animal cells
Microtubules
highways for intracellular active transport of vesicles, organelles, macromolecules; super dynamic (constant growing&shrinking) their polarity allows for directional transport; growth initiates at MTOC
Kinesin
plus end-directed motor protein that helps control transport on microtubule; stretches the ER along the microtubules like a net
dynein
minus end-directed motor protein that helps control transport on microtubules; pulls the Golgi towards the nucleus
Actin filaments
cortex stabilization; cell movement; muscle contraction; can be polymerized into a variety of useful shapes and structures; thin and flexible; grow in direction of cell movement
treadmilling
gain subunits at plus ends, lose subunits at the minus end (think actin filaments)
myosin
motor protein that moves along actin filaments; hydrolyzes ATP to fuel cycles of binding, release, rebinding; head domains binds actin, tail binds to cargo
Nuclear pore complexes
complex of different proteins that act as gates for letting molecules through nuclear envelope; proteins that line the central pore have extended unstructured regions that form a disordered meshwork
nuclear localization signals
sequences in a protein that bind receptors that direct proteins through the pore
GTPase switch
controls nuclear import/export; GTPase activates proteins (GAPs) which stimulates hydrolysis of GTP, guanine nucleotide exchange factors (GEF) exchange GDP for GTP
Ran GTPase
imposes directionality for nuclear transport
Immunoprecipitation
purification of a specific protein using antibody binding; combined with immunoblotting can detect protein-protein interactions
Endomembrane system
protein secretion system; nuclear envelope, ER, Golgi, early/late endosome, lysosome, transport vesicles, plasma membrane, cytosol
Endoplasmic reticulum
most extensive membrane system in a eukaryotic cell; processing of proteins; balances protein load with processing function
Signal recognition particle (SRP)
recognizes signal sequences for ER (hydrophobic amino acids); wraps around ribosome and binds near the catalytic site to pause translation
Glycosylation
covalent modification of a protein with oligosaccharides (usually short, branched chains of various sugars); protects proteins from degradation, serves as quality control checkpoint, targets the protein to a specific organelle, contributes to cell’s outer carbohydrate layer (plasma membrane proteins)
ER stress
imbalance between the load and capacity of ER
Unfolded Protein Response (UPR)
increase folding capacity & (temporarily) reduce load; either results in recovery and expansion of ER or apoptosis of cell
Golgi
sorts proteins; oligosaccharides attached to proteins; vesicles then take proteins to other parts of the cell (ER, lysosome via endosomes, plasma membrane, secretory vesicles); [FURTHER GLYCOSYLATION, SORTING]
constitutive secretion
replenishes plasma membrane lipids and proteins, allows cells to expand in size
regulated secretion
allows rapid release of specific proteins in response to a signal
Exocytosis
default pathway for proteins made at the Rough ER
endocytosis
process by which cells take in fluid, as well as large and small molecules, by invagination of the plasma membrane (how cells degrade and repurpose materials)