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Cell Bio Chapt 12-14
ER, Golgi, Peroxisomes, Endosomes, Lysosomes, Signal Transduction
| Question | Answer |
|---|---|
| Which of the following is incorrectly matched: A. rough ER and protein synthesis B. terminal glycosylation and Golgi C. Ca storage and smooth ER D. secretory vesicle shipping and cis-Golgi network E. transitional vesicle formation and rough ER | D. secretory vesicle shipping and cis-Golgi network |
| What makes up the endomembrane system? | ER, Golgi, lysosomes, and endosomes |
| Which of the following is not part of the endomembrane system: A. ER B. endosomes C. lysosomes D. peroxisomes E. Golgi | D. peroxisomes |
| A protein can be glycosylated and translated at the same time. | True |
| Flippases aid in attaching oligosaccharides to proteins. | False |
| Calreticulin binds to improperly folded proteins and targets them for degredation. | False |
| Transfer of oligosaccharides to proteins always occurs in ER lumen. | False |
| In receptor-mediated endocytosis, dynamin inhibition would prevent vesicle formation. | True |
| In receptor-mediated endocytosis, coated pits would form in the absence of adapter proteins as long as clathrin was present. | False |
| In receptor-mediated endocytosis, a coated vesicle can fuse with endosomes. | False |
| In receptor-mediated endocytosis, a ligand can bind to any receptor as long as it's on the cell surface. | False |
| Which of the following is not part of the vesicle-sorting pathway: A. v-SNARE B. Golgin C. m-SNARE D. Rab GTPase E. Syntaxin | C. m-SNARE |
| Syntaxin | type of v-SNARE |
| Golgin | type of tethering protein |
| Labeled protein seen only in ER | protein contains RXR (Arg-X-Arg) retention tag |
| Anterograde pathway through endomembrane system | rough ER -> cis-Golgi network -> trans-Golgi network -> plasma membrane |
| The smooth ER is enriched in glycogen-6-phosphatase which helps break down glycogen. | False--glucose-6-phosphatase |
| What is the oligosaccharide carrier in glycosylation called? | dolichol phosphate |
| Zymogen granules are part of constitutive secretory pathway. | False |
| GTP-bound SarI recruits and binds COP I proteins for vesicle coat formation. | False--SarI goes with COP II, COP I goes with ARF |
| Step #1 of lysosomal protein targeting | N-glycosylation |
| Step #2 of lysosomal protein targeting | transition vesicle formation |
| Step #3 of lysosomal protein targeting | mannose phosphorylation |
| Step #4 of lysosomal protein targeting | receptor binding |
| Step #5 of lysosomal protein targeting | increase in lumen [H+] |
| The continuous secretion of mucus from epithelial cells in your intestines is an example of what type of exocytosis? | constitutive/continuous secretion/exocytosis |
| Where are glycosyl transferases found? | in Golgi |
| What do glycosyl transferases do? | transfer oligosaccharides to glycoproteins (goes with glucan synthatase) |
| Which is needed for synthesis of proteins in ER: A. KDEL tag B. cytosolic ribosome C. SRP D. cytosolic ribosome and KDEL tag E. SRP and cytosolic ribosome | E. SRP and cytosolic ribosome |
| Functions of the ER | "production line": protein synthesis, lipid synthesis, and membrane synthesis |
| Transitional elements (TEs) | help transport "packages" from ER to Golgi |
| _______ is recruited by an ER signal sequence on a cytoplasmic ribosome, and then binds to rough ER so protein synthesis can continue. | SRP |
| Step #1 of protein modification and degredation | glycosylation produces glycoproteins |
| glycosylation | the attachment of carbohydrate chains to proteins |
| glycoproteins | proteins with carbohydrate chains |
| Step #2 of protein modification and degredation | protein folding and assembly |
| Step #3 of protein modification and degredation | ER-associated degredation (ERAD) |
| ER-associated degredation (ERAD) | improperly folded proteins are exported for degredation |
| hydroxylation | OH groups are added to make drugs/toxins more soluble (less toxic) |
| monooxygenase | in cytochrome P-450, the enzyme involved in hydroxylation |
| aryl hydrocarbon hydroxylases | in cyt P-450, the enzymes that targets polycyclic hydrocarbons |
| Carbohydrate metabolism in smooth ER Step #1 | glucose stored as glycogen (glucose polymer) |
| Carbohydrate metabolism in smooth ER Step #2 | glycogen is broken down into glucose-1-phosphate |
| Carbohydrate metabolism in smooth ER Step #3 | glucose-1-phosphate is made into glucose-6-phosphate |
| Carbohydrate metabolism in smooth ER Step #4 | glucose-6-phosphatase removes the phosphates from glucose-6-phosphate to make glucose |
| sarcoplasmic reticulum | smooth ER found in muscle cells involved in muscle contraction/relaxation |
| HMG-CoA reductase | enzyme crucial for cholesterol synthesis target for statin drugs that try to lower cholesterol |
| smooth ER functions | detoxification, carbohydrate metabolism, calcium storage, and biosynthesis of steroids |
| ________ and _________ are the main components of membranes | phospholipids and cholesterols |
| What membranes are produced in the ER? | all except mitochondria, chloroplast, and peroxisome membranes |
| phospholipid translocators | flippases, aid in flip-flop/transverse diffusion |
| Cis-Golgi Network (CGN) | faces ER, "recieving" |
| Golgi medial cisternae | middle, contains lumen, "sorting and processing" |
| Trans-Golgi Network (TGN) | opposite side of CGN, "shipping" |
| Golgi Stationary Cisternae Model | each compartment of the Golgi is stationary, and shuttle vesicles transport between cis and trans |
| Golgi Cisternae Maturation Model | compartments of the Golgi are transient and dynamic |
| anterograde transport | ER -> Golgi -> plasma membrane |
| retrograde transport | plasma membrane -> Golgi -> ER |
| Where does protein glycosylation occur? | ER and Golgi |
| N-glycosylation | linkage of sugar molecules |
| O-glycosylation | attachment of carbohydrates to molecules |
| Where does glycosylation begin? | ER membrane |
| glycosylation in ER membrane step #1 | biosynthesis and processing of carbohydrate chains |
| glycosylation in ER membrane step #2 | identification and removal of misfolded proteins |
| glycosylation in ER membrane step #3 | attachment of carbohydrate chain to protein |
| glycosylation in Golgi step #1 | addition or removal of carbohydrate chains |
| dolichol phosphate | olgigosaccharide carrier in ER lumen |
| calnexin (CNX) | membrane-bound protein involved in protein folding |
| calreticulin (CRT) | soluble protein involved in protein folding |
| UDP-glucose glycoprotein transferase (UGGT) | enzyme that binds to improperly folded proteins to signal to CNX or CRT that they need fixed |
| glucan synthetases | enzymes that produce olgiogosaccharides from monosaccharides in the ER |
| glycosyl transferases | enzymes that attach carbohydrate groups to proteins in the ER |
| ________are found in localized proteins. | retention tags |
| RXR | retention tag Arg-X-Arg |
| ________bind to Golgi receptors and transport a protein back to the ER. | retrieval tags |
| KDEL | retrieval tag Lys-Asp-Glu-Leu |
| KKXX | retrieval tag Lys-Lys-X-X |
| Where are hydrolytic enzymes found? | within lysosomes |
| _______is a type of vacuole that becomes a secretory vesicle. | condensation vacuole (CV) |
| _______are mature secretory vesicles that form from CVs | zymogen granules (ZG) |
| Secretory pathway to plasma membrane | rough ER -> Golgi -> aggregate into CV -> CV becomes ZG as more aggregate -> secretion |
| Constitutive secretion is_______. | continuous |
| In __________ ___________, secretory vesicles accumulate until an extracellular signal is recieved. | regulated secretion |
| Exocytosis is transport ______ cell. | out of |
| Endocytosis is transport _____ cell. | into |
| ________-________ is regulated exocytosis that responds to ____ within a cell, and is found in the smooth ER. | calcium-triggered, [Ca] |
| ______ ______ is exocytosis at very specific sites in the plasma membrane, and is found in nerve cells. | polarized secretion |
| "cellular eating"/intake of large particles | phagocytosis |
| _____ _____ are indigestible materials left in lysosomes that can be expelled into the cytoplasm, and accumulation of it can determine cellular aging. Macrophages also transport these to the immune system to help the body recognize and fight infections. | residual bodies |
| autophagy | organelle digestin/recycling |
| autophagosome | lysosome used in autophagy |
| macrophagy | autophagy of large organelles |
| What are the causes of lysosomal storage diseases? | the accumulation of polysaccharides or lipids in organs, and/or missing digestive enzymes |
| The accumulation of glycogen in different organs (liver, heart, skeletal muscle) is the cause of ____ ____ ____. | Type II Glycogenosis |
| The accumulation of gangliosides (lipids) in the brain causes ____-____ ____. | Tay-Sachs Disease |
| The accumulation of glycosaminoglyccans in ECM causes ___ ___ ___ ___. | Hurler and Hunter Syndrome |
| peroxisomes | single membrane-bound organelles not derived from ER |
| catalase | enzyme found in peroxisomes that breaks down hydrogen peroxide |
| oxidase | enzyme found in peroxisomes that makes hydrogen peroxide |
| peroxidases | both oxidize and break down hydrogen peroxide |
| reactive oxygen species | hydrogen peroxide, O2-, OH+ |
| Beta (B) oxidation | fatty acid oxidation in peroxisomes, and produces acetyl CoA/succinyl CoA for Krebs cycle |
| aminotransferases | move amino groups around on molecules |
| leaf peroxisomes | close to mitochondria and chloroplasts, involved in photorespiration |
| glyoxysomes | convert fats/fatty acids to sugars/sucrose, and are present in fat-storage tissues (endosperm), and they become peroxisomes as plants mature and no longer need the endosperm |
| peroxisome biogenesis | replication of peroxisomes |
| peroxin | trans-membrane protein that helps bring in catalases |
| peroxisome targeting sequence | SKL (Ser-Lys-Len)/PTS-1 found at end of a protein |
| Vm | resting membrane potential, -60 mV for most cells |
| electrical excitability | the response to stimuli resulting in changes in the Vm (action potential), and it is rapid and reversible |
| electroneutrality | in solution, for each ion, A, ther is an equal amount of oppositely charged ions, B |
| current | the movement of the ions |
| electrical potential (voltage) | "opposites attract" |
| selective permeability: Na+/K+ pumps | ion channels control what goes in and out of cell |
| cation channel leakage | some ions go in/out that should not |
| electrochemical equilibrium | forces that pull cations out = forces that pull them in |
| Nerst Equation | shows relationship between ion gradient and equilibrium potential for a selectively permeable membrane, but only considers one ion |
| net charge inside cell | negative |
| net charge outside cell | positive |
| repolarization | K+ flows out of cell (outflux)/Vm becomes more negative |
| depolarization | Nat+ flows into cell (influx)/Vm becomes more positive |
| Goldman Equation | considers all ions and relative permeability |
| multimeric voltage-gated channels | K+ channels made up of 4 proteins |
| monomeric voltage-gated channels | Nat+ channels made up of 1 protein |
| inactivating particle | helps regulate voltage-gated channels |
| voltage sensor | detects signal and tells channel to open or close, S4 |
| ____-____ ____ uses specific receptors that are found on the outer surface of the plasma membrane. | receptor-mediated endocytosis |
| Step #1 in receptor-mediated endocytosis | ligands bind to receptors on outer surface of plasma membrane |
| coated pits | specialized membrane regions that serve as sites for collection and internalization of receptor-ligand complexes |
| Step #2 in receptor-mediated endocytosis | receptor-ligand complexes encounter coated pits |
| Step #3 in receptor-mediated endocytosis | accumulation of receptor-ligand complexes triggers accumulation of additional proteins (adaptor proteins, clathrin, and dynamin) on cytosolic surface of plasma membrane |
| Step #4 in receptor-mediated endocytosis | invagination of plasma membrane continues until it pinches off and forms a coated vesicle |
| Step #5 in receptor-mediated endocytosis | clathrin coat is released to leave the vesicle uncoated |
| Step #6 in receptor-mediated endocytosis | coat proteins and dynamin are recycled to plasma membrane, and become available for formation of new vesicles while uncoated vesicle is able to fuse with an early endosome |
| desenstitization | EGF receptor internalization leads to the cell becoming less receptive to EGF |
| early endosomes | sites for the sorting and recycling of extra-cellular material brought into the cell by endocytosis |
| ATP-dependent proton pump | found in the endosomal membrane and maintains the lower pH |
| transcytosis | a pathway that takes extracellular material from one side of the cell (endocytosis) to the opposite side (exocytosis) |
| fluid-phase endocytosis | a cltahrin-independent endocytic pathway that takes in extracellular fluid |
| clathrin | coat protein that goes with AP1, AP2, and ARF; vesicles involved in selective transport of proteins from TGN to endosomes and in the endocytosis of receptor-ligand complexes from the plasma membrane |
| COPI | coat protein that goes with ARF; facilitate retrograde transport of proteins from Golgi to ER, Golgi and cisternae |
| COPII | coat protein that goes with Sar I; involved in transport of material from ER to Golgi |
| Caveolae | small invaginations of plasma membrane characterized by protein caveolin; type of lipid raft rich in cholesterol and shipgolipids |
| triskelions | a multimeric protein composed of three large polypeptides and three small polypeptides radiating from a central vertex; component of clathrin coats |
| adapter protein (AP) | component of clathrin coats; ensure that appropriate macromolecules are converted in coated pits, mediate attachment of clathrin to proteins embedded in plasma membrane |
| dynnamin | a cytosolic GTPase required for coated pit constriction and closing of the budding vesicle |
| uncoating ATPase | essential for uncoating mechanism |
| ADP ribosylation factor (ARF) | small GTP-binding protein, mediates COPI protein |
| SNARE hypothesis | the proper sorting and targeting of vesicles in eukaryotic cells involves two families of SNARE/SNAP receptor proteins (v and t-SNARE) found on transport vesicles and target membranes |
| v-SNARE (vesicle-SNAP receptors) | found on transport vesicles, complementary with t-SNARES so that vesicles can recognize and fuse with target membrane |
| t-SNARE (target-SNAP receptors) | found on target membranes, complementary with v-SNARES so that vesicles can recognize and fuse with target membrane |
| Rab GTPases | facilitates membrane fusion by locking complementary t-SNARE and v-SNARE together |
| N-ethylmaleimide-sensitive factor (NSF) | mediates release of v and t-SNARES of donor and target membranes along with SNAPs |
| soluble NSF attachment proteins (SNAPs) | mediate release of v and t-SNARES of donor and target membranes along with NSF |
| tethering proteins | act over longer distances and provide specificity by connecting vesicles to target membranes before v-SNARE/t-SNARE interactions; two main types: coiled-coil proteins, multisubunit complexes |
| golgins | coiled-coil proteins used in initial recognition of COPI or COPII coated vesicles to Golgi |
| What do conserved oligomeric Golgis (COG), Goldi-associated retrograde proteins (GARP), and transport protein particles (TRAPP) have in common? | they are multisubunit tethering complexes implicated in the initial recognition and specificity of vesicle-target membrane interaction |
| inactivating particles | block channel pore so gate will not open until it receives a signal telling it to leave |
| action potential | significant depolarization and repolarization of neuronal plasma membrane |
| threshold potential | the upper limit of Vm that induces the action potential; point where large change in voltage occurs |
| propagation | the transfer of the action potential through nerves |
| resting potential | voltage gates are closed |
| subthreshold depolarization | blips of activity due to leakage that do not cause action potentials because threshold is not reached |
| depolarization phase | cell has increased permeability to Na+ |
| depolarization stimulus | takes voltage to threshold and Na+ rushes into the cell |
| repolarization phase | peak membrane potential is reached, and Na+ channels are inactivated while K+ channels open |
| absolute refractory period | no more depolarization occurs |
| hyperpolarization phase | Na+ channels remain inactivated while K+ channels remain open and voltage goes below membrane potential before voltage goes back up to membrane potential and both gates close |
| relative refactory period | hyperpolarization occurs |
| axon hillock | has lots of Na+ channels, where action potential has to hit before it can rapidly continue down the axon |
| passive spread | action potential in the cell body because Na+ and K+ channels are not as efficiently distributed |
| nerve impulse | transmission and propagation of action potential along axon |
| myelin sheath | insulates axon at specific points to allow faster and farther propagation, made of Schwann cells |
| Nodes of Ranvier | where Schwann cells taper off, where action potentials are triggered on the axon |
| saltatory propagation | happens with myelin insulated axon, faster than continuous propagation |
| synapse | space between two adjacent neurons |
| electrical synapses | have gap junctions to connect neurons to help propagate signal |
| chemical synapse | synaptic cleft separates neurons, so neurotransmitters are needed to propagate signal |
| connexon | made of connex in subunits (proteins) that make up pore/channels between neurons |
| synaptic vesicles | contain neurotransmitters that bind to postsynaptic membrane receptors in exocytosis |
| ionotropic receptors | neurotransmitter acts as ligand and binds to receptor to open channel (direct) |
| metabotropic receptors | neurotransmitter binds to receptor and receptor signals for the channel to open (indirect) |
| excitatory receptor | depolarization of presynaptic neuron when neurotransmitter binds |
| inhibitory receptor | hyperpolarization when neurotransmitter binds |
| necessary properties of neurotransmitters | elicit appropriate response in synaptic cleft, occur naturally in presynaptic neuron, released at correct time |
| acetylcholine | type of neurotransmitter found in CNS, PNS, neuromuscular junctions that binds to cholinergic synapses |
| catecholamines | neurotransmitters that are derivitives of tyrosine synthesized in the adrenal gland, and bind to adrenergic synapses |
| dopamine | type of catecholamine neurotransmitter that is generally excitatory |
| norepinephrine | type of catecholamine neurotransmitter that is generally excitatory |
| seratonin | neurotransmitter that is a derivitive of tryptophan found in the CNS (controls sleep, memory, mood, appetite), and can be excitatory or inhibitory |
| amino acid neurotransmitters | glycine (inhibitory), glutamate (excitatory) |
| neuropeptides | neurotransmitters that are short chains of amino acids that can be inhibitory or excitatory and have longer lasting effects (enkephalines, pain perception) |
| synaptotagmin | Calcium sensor that tells vesicles when to go |
| nicotinic acetylcholine receptor (nAchR) | causes depolarization when 2 acetylcholine binds to alpha subunits |
| GABA receptor | causes hyperpolarization when gamma-aminobutyric acid binds |
| types of inactivation of neurotransmitters after release | degredation, re-uptake |
| temporal summation | signals from one neuron until action potential is made |
| spatial summation | take signals from many neurons to make action potential |
| Secretion of neurotransmitter step #1 | action potential in bouton -> depolarization |
| Secretion of neurotransmitter step #2 | depolarization -> voltage-gated calcium channel opens |
| Secretion of neurotransmitter step #3 | calcium rushes into bouton (further depolarization) -> secretion |
| Secretion of neurotransmitter step #4 | reserve vesicles move up for next action potential/diffusion of neurotransmitter across synaptic cleft to receptors on dendrite or soma |
| Secretion of neurotransmitter step #5 | binding of neurotransmitters to receptors -> ion channels open |
| Secretion of neurotransmitter step #6 | if threshold potential is reached in post synaptic neuron -> AP in post synaptic cell |
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