Cell Bio - Exam 2

Question 1 of 212

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Post-translational translocation of non-secretory proteins across membranes could occur in which organelles?

Select one or more of the following:

  • mitochondria

  • chloroplasts

  • nuclei

  • Golgi

  • ER

  • peroxisomes

  • lysosomes

Question 2 of 212

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Select the correct sequential steps for cotranslational translocation (signal hypothesis):

Select one or more of the following:

  • ER signal sequence is translated at free ribosome

  • Sequence allows ribosome to bind to a translocator on RER

  • Pore is formed and polypeptide is translated through to the RER lumen

  • Signal peptidase cleaves signal sequence

  • Protein is released into the ER lumen

Question 3 of 212

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The discovery of cotranslational translocation involved:

Select one of the following:

  • Secretory proteins translated in vitro were smaller than those in vivo. Microsomes from ER added to in vitro proteins resulted in larger size.

  • Secretory proteins were the same size in vitro and in vivo.

  • Secretory proteins translated in vitro were larger than those in vivo. Microsomes from ER added to in vitro proteins resulted in correct size.

Question 4 of 212

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Signal sequences:

Select one of the following:

  • vary greatly but have 6+ hydrophobic aa string at N terminus

  • vary greatly but have 8+ hydrophobic aa string at N terminus

  • vary greatly but have 6+ hydrophobic aa string at C terminus

  • vary greatly but have 8+ hydrophobic aa string at C terminus

Question 5 of 212

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Signal recognition particle can bind to signal sequences of multiple shapes and sizes because:

Select one of the following:

  • Hydrophilic pocket lined with methionine, which has inflexible side chains.

  • Hydrophobic pocket lined with methionine, which has flexible side chains.

  • Hydrophobic pocket lined with methionine, which has inflexible side chains.

Question 6 of 212

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Select the steps for SRP function:

Select one or more of the following:

  • SRP binds to small ribosomal subunit

  • SRP binds to large ribosomal subunit.

  • Binding pocket fits around nascent chain exit site and binds to ER signal sequence.

  • Translational pause domain positions at interface between ribosomal subunits.

  • SRP binds to SRP-R.

  • Mechanism possibly related to GDP binding sites near SRP-R.

  • SRP released, translation continues embedded in ER.

  • ER signal sequence binds to hydrophobic site on inside of locator, opening the channel.

  • Polypeptide extruded into ER, peptidase cleaves signal.

Question 7 of 212

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ER signal sequence is checked:

Select one of the following:

  • One time. SRP.

  • Two times. SRP, SRP-R.

  • Three times. SRP, SRP-R, signal peptidase.

Question 8 of 212

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Translocator for secreted proteins in ER is called:

Select one of the following:

  • Sec 59.

  • Sec 51.

  • Sec 61.

  • Sec 63.

Question 9 of 212

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Sec 61 has opening in side for:

Select one or more of the following:

  • Integration of TMDs.

  • Cleaved signal sequence to diffuse into membrane.

  • Ribosome to insert peptide from side.

  • Hydrophobic influence in Sec 61 pore.

Question 10 of 212

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A type I TMD has:

Select one or more of the following:

  • N terminus in ER lumen.

  • C terminus in ER lumen.

Question 11 of 212

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A type II TMD has:

Select one or more of the following:

  • N terminus in ER lumen.

  • C terminus in ER lumen.

Question 12 of 212

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For 1 pass TMDs, orientation is determined by:

Select one of the following:

  • Location of (+) charge, always goes to cytosol

  • Location of (+) charge, always goes to ER lumen

  • Location of 3 aa repeat, always goes to cytosol

  • Location of 3 aa repeat, always goes to ER lumen

Question 13 of 212

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In two TMD insertion, the signal is cleaved.

Select one of the following:

  • True
  • False

Question 14 of 212

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In multiple TMD insertion:

Select one of the following:

  • There is an internal start-transfer sequence and C-terminus stop-transfer sequence.

  • There is an N-terminus start-transfer sequence and a C-terminus stop-transfer sequence.

  • There is an internal start-transfer sequence and internal stop-transfer sequence.

  • There is an N-terminus start-transfer sequence and an internal stop-transfer sequence.

Question 15 of 212

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Many ER resident proteins stay in the ER because:

Select one of the following:

  • They have an ER retention signal.

  • They are too small to be absorbed into vesicles.

  • They are anchored on a special receptor called ER-R.

Question 16 of 212

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PDI is:

Select one of the following:

  • Protein disulfide isomerase.

  • Protein disulfur isomerase.

  • Protein disulfide isomerate.

  • Protein disulfur isomerate.

Question 17 of 212

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PDI's function is:

Select one of the following:

  • Formation of disulfide bonds between sulfhydryls of cysteins.

  • Formation of disulfide bonds between sulfhydryls of nucleotides.

  • Binding to unfolded proteins to prevent aggregation.

  • Binding to unfolded proteins to facilitate aggregation.

Question 18 of 212

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BiP is:

Select one of the following:

  • Binding Protein.

  • Binder Protein.

  • Binding in Protein.

Question 19 of 212

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BiP functions by:

Select one of the following:

  • Binding to unfolded proteins and preventing aggregation.

  • Binding to unfolded proteins and promoting aggregation.

  • Forming disulfide bonds between sulfhydryls of cysteins.

  • Forming disulfide bonds between sulfhydryls of nucleotides.

Question 20 of 212

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BiP and PDI aid in:

Select one or more of the following:

  • Secretory pathway in the Golgi.

  • Secretory pathway in the ER.

  • Proper folding of proteins.

  • Aggregation of proteins.

Question 21 of 212

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Glycosylation aids in:

Select one or more of the following:

  • Folding proteins.

  • Protecting against degradation.

  • Cell communication.

  • Sorting.

Question 22 of 212

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Which is more common at 90%?

Select one of the following:

  • N-linked glycosylation.

  • O-linked glycosylation.

Question 23 of 212

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N-linked glycosylation occurs by attaching sugar residues to:

Select one of the following:

  • Amide nitrogen of asparagine.

  • Amide nitrogen of cysteine.

  • Amide nitrogen of serine.

Question 24 of 212

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OST is:

Select one of the following:

  • oligosaccharyl transferase.

  • oligosaccglycol transferase.

  • oligoseryl transferase.

Question 25 of 212

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OST transfers what structure to the target side chain during N-linked glycosylation?

Select one of the following:

  • 14 sugar compound of GlcNAc, mannose, glucose.

  • 14 sugar compound of GlcNAc, mannose.

  • 16 sugar compound of GlcNAc, mannose, glucose.

  • 16 sugar compound of GlcNAc, mannose.

Question 26 of 212

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OST glycosylates:

Select one of the following:

  • All asparagines.

  • Only asparagines within a specific sequence (Asn - X - Ser/Thr).

Question 27 of 212

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Initial sugars that form the basis of all N-linked glycosylations are:

Select one of the following:

  • 2 GlcNAc, 3 Man

  • 3 GlcNAc, 2 Man

  • 2 Glu, 3 GlcNAc

  • 3 Glu, 2 GlcNAc

  • 2 Man, 3 Glu

  • 3 Man, 2 Glu

Question 28 of 212

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OST aids in glycosylation of cytosolic proteins.

Select one of the following:

  • True
  • False

Question 29 of 212

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Dolichol:

Select one or more of the following:

  • Holds sugar structure awaiting transfer by OST.

  • Builds sugar structure awaiting transfer by OST.

  • Facilitates ATP hydrolysis of OST.

  • Holds energy for sugar transfer in pyrophosphate bond.

  • Uses ATP to transfer sugar.

  • Uses GTP to transfer sugar.

Question 30 of 212

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OST:

Select one of the following:

  • Is associated with every Sec 61 translocator and each has a dolichol anchor nearby.

  • Is associated with some Sec 61 translocators and each has a dolichol anchor nearby.

  • Is associated with all Sec 61 translocators but not dolichols.

Question 31 of 212

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OST catalyzes the addition of sugar groups:

Select one of the following:

  • During translation of the target protein.

  • After the signal peptide is cleaved.

  • The instant translation finishes.

Question 32 of 212

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Which sugar combination is associated with entrance into the Golgi?

Select one of the following:

  • 8 Man, 2 GlcNAc

  • 6 Man, 2 GlcNAc

  • 2 Man, 8 GlcNAc

  • 2 Man, 6 GlcNAc

Question 33 of 212

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O-linked glycosylation:

Select one or more of the following:

  • Makes up about 90% of glycosylation events.

  • Makes up about 10% of glycosylation events.

  • Involves attachment of sugar to hydroxyl group of serine.

  • Involves attachment of sugar to hydroxyl group of threonine.

Question 34 of 212

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Synthesis of precursor oligosaccharide begins:

Select one of the following:

  • In membrane layer.

  • Cytosolic face.

  • ER lumen face.

Question 35 of 212

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Dolichol:

Select one of the following:

  • Is very hydrophobic, spans bilayer 3+ times.

  • Is very hydrophilic, spans bilayer 3+ times.

  • Is very hydrophobic, spans bilayer 2 times.

  • Is very hydrophilic, spans bilayer 2 times.

Question 36 of 212

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Synthesis on dolichol:

Select one of the following:

  • Is en bloc.

  • Is one sugar at a time.

Question 37 of 212

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Dolichol's pyrophosphate bond is located:

Select one of the following:

  • In the membrane.

  • Within dolichol.

  • Between dolichol and the sugar group.

  • In the sugar group.

  • On the end of the sugar group.

Question 38 of 212

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During flip of dolichol, (Glc)3(Man)9(GlcNAc)2 turns into (GlcNAc)2(Man)5.

Select one of the following:

  • True
  • False

Question 39 of 212

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ER chaperones require:

Select one of the following:

  • K+

  • Ca2+

  • H+

  • Mg2+

Question 40 of 212

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Calnexin & calreticulin:

Select one of the following:

  • Prevent unproperly folded proteins from leaving the ER.

  • Keep ER resident proteins critical for proper folding inside the ER.

  • Are the only proteins needed for proper management of proteins in the ER.

Question 41 of 212

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Calnexin is membrane bound.

Select one of the following:

  • True
  • False

Question 42 of 212

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Calreticulin is membrane bound.

Select one of the following:

  • True
  • False

Question 43 of 212

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Select the proper steps for calnexin function:

Select one or more of the following:

  • Calnexin recognizes a single glucose after glucose trimming.

  • Calnexin recognizes a double glucose after glucose trimming.

  • ER resident glucosidase removes final glucose(s) off of protein.

  • Calreticulin recognizes absence of glucose and binds.

  • If proper folding occurs, protein is bound by glucosyl transferase.

  • Inproperly folded proteins have sugars added back onto their N-linked oligo to go back through cycle.

Question 44 of 212

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If proper folding fails:

Select one or more of the following:

  • Protein goes through retrotranslocation.

  • Protein possibly goes back through Sec61.

  • N-glycanase removes oligosaccharide chains en bloc in ER.

  • Oligosaccharide chains removed in cytosol.

  • Ubiquitin marks proteins for degradation by recognizing certain sequences that should not be exposed in properly-folded proteins.

  • Lysosome breaks down ubiquitin-marked proteins.

  • Proteaomse processes ubiquitin-marked proteins.

Question 45 of 212

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Consider proteins that take too long to fold:

Select one or more of the following:

  • They are processed in the same manner as proteins that are incorrectly folded once recognized.

  • They have an organic timer mediated by mannosidase.

  • Calnexin cycle resets the mannose timer.

  • Proteins that fold properly keep all their mannoses.

Question 46 of 212

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Unfolded protein response involves:

Select one or more of the following:

  • Accumulation of unfolded proteins in ER.

  • Activation by high proteasome activity.

  • Increased transcription of genes involving ER chaperones, retrotranslocation proteins, protein-folding proteins.

  • Involve IRE1.

Question 47 of 212

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IRE1:

Select one or more of the following:

  • is a transmembrane protein kinase.

  • is an ER chaperone catalyst.

  • autophosphorylates.

  • dimerizes.

  • trimerizes.

  • has endoribonuclease domain that edits a specific mRNA in cytosol.

  • affects activation of genes in nucleus through mRNA editing.

  • enters the nucleus after signaling to affect gene transcription.

Question 48 of 212

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____ controls coat assembly.

Select one of the following:

  • GTP binding protein.

  • Sar1.

  • Sec61.

  • ATP binding protein.

  • ATPase.

Question 49 of 212

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GEF is:

Select one of the following:

  • guanine nucleotide exchange factor.

  • guanine export factor.

Question 50 of 212

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Sar1 is associated with COPI vesicles.

Select one of the following:

  • True
  • False

Question 51 of 212

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Sec12:

Select one or more of the following:

  • is an ER membrane protein.

  • is a cytosolic protein.

  • is a type of GEF.

  • binds Sar1-GDP and catalyzes release of GDP and binding of GTP.

  • binds Sar1-GTP and catalyzes hydrolysation and subsequent release of GDP.

  • is involved with COPI vesicles.

  • is involved with COPII vesicles.

Question 52 of 212

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Select the correct steps for COPII coat assembly:

Select one or more of the following:

  • Sar1-GTP serves as a binding site for Sec23 & 24.

  • Sec23 & 24 select cargo.

  • Sec13 & 31 proteins form second layer to COPII structure.

  • Sec16 increases coat polymerization efficacy.

  • Sec17 increases coat polymerization efficacy.

  • Sec23 promotes GTP hydrolysis of Sar1-ATP.

  • Sec23 promotes GTP hydrolysis of Sar1-GTP.

  • Sar1-GDP is released from vesicle membrane, allowing coat to rapidly dissemble.

  • t-SNARE is exposed on surface, allowing fusing process to begin.

  • v-SNARE is exposed on surface, allowing fusing process to begin.

Question 53 of 212

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Rab-GDP is active in the cytosol.

Select one of the following:

  • True
  • False

Question 54 of 212

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Rab-GTP is free in the cytosol.

Select one of the following:

  • True
  • False

Question 55 of 212

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Select the correct steps for vesicle fusion:

Select one or more of the following:

  • Vesicle binding is mediated by Rab GTPase.

  • Cytosolic Rab-GDP converted to Rab-GTP by GEF.

  • Rab-GTP binds to Rab effector on target membrane.

  • t-SNARE and v-SNARE become close enough to interact and "hook."

  • NSF with an alpha-SNAP binds the SNAREs.

  • NSF catalyzes hydrolysis of ATP, forming energy needed to dissociate SNARE complexes.

  • Rab protein hydrolyzes its bound GTP releasing Rab effector.

  • Rab-GDP is released into cytosol for next cycle.

Question 56 of 212

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Studies with VSVG-GFP revealed:

Select one or more of the following:

  • Some vesicles detached from the ER directly fused with the Golgi if the travel distance was short.

  • COPII vesicles traveled toward the Golgi when originally thought COPII did retrograde transport back to the ER.

  • If Golgi was several micrometers away, vesicles en route to Golgi fused prior to Golgi contact, forming cis-Golgi network.

  • Retrograde vesicles budded off the Golgi toward the ER.

  • trans-Golgi network formed after trans-Golgi pushed out of Golgi from cisternal maturation.

Question 57 of 212

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Purpose of retrograde transport to ER:

Select one or more of the following:

  • Return t-SNARE.

  • Return v-SNARE.

  • Return membrane to ER.

  • Retrieve ER resident proteins.

  • Bring proteins back for new modifications before packaging to PM.

Question 58 of 212

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Retrograde transport to ER from Golgi involves COPI while retrograde transport from Golgi to Golgi involves COPII.

Select one of the following:

  • True
  • False

Question 59 of 212

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COPI coat proteins are composed of:

Select one or more of the following:

  • 6 large cytosolic polypeptide complexes (coatomers).

  • 4 large cytosolic polypeptide complexes (coatomers).

  • Coatomers with alpha and beta subunits.

  • Whole coatomers, no subunits.

Question 60 of 212

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COPI vesicles are controlled by:

Select one of the following:

  • Sec12, a GEF.

  • ARF (ADP ribosylation factor).

  • Sar1, a GTP-binding factor.

Question 61 of 212

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Select the proper steps for COPI formation:

Select one or more of the following:

  • ARF-GDP is weakly tethered to the Golgi membrane by a weak covalent protein mod on N-terminus.

  • ARF-GTP is strongly tethered to the Golgi membrane by a strong covalent protein mod on N-terminus.

  • GEF on Golgi catalyzes formation of ARF-GTP. ARF now strongly tethered to Golgi membrane.

  • Tight association of ARF-GTP serves as foundation for coatomer formation on COPI vesicles.

  • Coat dissembles and Rab mediates binding to target membrane.

  • SNARES facilitate fusion to target membrane.

Question 62 of 212

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Yeast COPI mutants showed protein accumulation in ER. This was because...

Select one of the following:

  • Mutant COPI vesicles lacked the ability to perform vesicle transport of proteins to the Golgi apparatus.

  • Mutant COPI vesicles successfully formed vesicles, but the mutation made them immediately fuse back with the ER so transport did not occur.

  • Mutant COPI vesicles could not bring back proteins necessary for anterograde transport to continue.

  • Mutant COPI vesicles fused readily with COPII vesicles, interrupting the transport chain.

Question 63 of 212

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Because ER resident proteins are so abundant...

Select one or more of the following:

  • They easily get trapped in outgoing vesicles.

  • Retrograde transport is necessary to maintain presence of ER resident proteins in the ER.

  • Specialized receptors prevent ER resident proteins from getting entrapped in outgoing vesicles.

  • ER resident proteins are mostly free in the ER lumen, so outgoing vesicles usually do not trap ER resident proteins, and the cell can replace readily those that do.

Question 64 of 212

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Soluble ER resident proteins are targeted back to the ER...

Select one of the following:

  • By an ER retention signal (KDEL) that passes directly to the membrane, causing a COPI vesicle to form.

  • By an ER retention signal (KDEL) that binds to a special KDEL Receptor in low pHs, allowing retrograde transport.

  • By an ER retention signal (KDEL) that binds to a special KDEL Receptor in high pHs, allowing retrograde transport.

  • By an ER retention signal (KDEL) that binds to KDEL Receptor on COPII vesicles, essentially redirecting the vesicle to the ER before fusion with the Golgi.

Question 65 of 212

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What special signal targets KDEL receptor back to the ER?

Select one of the following:

  • KKXX signal on C terminus.

  • KKXX signal on N terminus.

  • KDEL signal on C terminus.

  • KDEL signal on N terminus.

  • 3 Man, 2 Glu on C terminus.

  • 3 Man, 2 Glu on N terminus.

Question 66 of 212

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KDEL Receptor binds to KDEL to:

Select one of the following:

  • Take back ER resident proteins.

  • Forward modified proteins to the next part of the Golgi.

Question 67 of 212

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KDEL binds at:

Select one of the following:

  • low pH.

  • high pH.

Question 68 of 212

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KDEL is released from KDEL-R at:

Select one of the following:

  • low pH.

  • high pH.

Question 69 of 212

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ER has a ____ pH compared to the Golgi.

Select one of the following:

  • lower

  • higher

Question 70 of 212

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KKXX binds to:

Select one of the following:

  • outer phospholipids of COPI vesicles.

  • alpha and beta subunits of COPI vesicles.

  • special KDEL-R receptor on COPI vesicles.

  • KDEL-R.

Question 71 of 212

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It's been observed that yeast mutants that lack COPI alpha and beta subunits:

Select one of the following:

  • still have successful retrograde transport of KDEL-signal proteins.

  • have proteins that need to be transported back to the ER remaining in the Golgi.

  • send KDEL-marked proteins to lysosomes.

  • lack the problem of having ER-resident proteins being erroneously sent to the Golgi.

Question 72 of 212

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Forward movement of proteins through the Golgi involves vesicles.

Select one of the following:

  • True
  • False

Question 73 of 212

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Backward movement of Golgi enzymes involves vesicles.

Select one of the following:

  • True
  • False

Question 74 of 212

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In cisternal maturation, trans becomes medial and medial becomes cis.

Select one of the following:

  • True
  • False

Question 75 of 212

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Scale-covered algae:

Select one of the following:

  • had cell-wall glycoproteins assembled in the Golgi that were 20X larger than any observed vesicle.

  • had cell-wall glycoproteins that were small enough to fit inside vesicles.

  • had cell-wall glycoproteins that were about as large as vesicles, spurring additional research into cisternal maturation.

Question 76 of 212

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Collagen synthesis by fibroblasts:

Select one or more of the following:

  • involves precollagen, a precusor too large for vesicles.

  • involves precollagen aggregates, which have never been seen in vesicles.

  • provides evidence for cisternal maturation.

  • provides evidence for anterograde vesicular transport in the Golgi.

  • provides evidence that retrograde Golgi transport of enzymes occurs.

  • involves trimming of precollagen, the pieces of which are transported backwards via vesicles in the Golgi.

  • involves COPII vesicles to bring enzymes in the Golgi forward as cisternal maturation occurs.

Question 77 of 212

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Enzymes move retrograde in the Golgi via:

Select one of the following:

  • COPI vesicles.

  • COPII vesicles.

  • They don't. They move back in the same compartment via cisternal maturation.

Question 78 of 212

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The Golgi does what to secreted proteins during processing?

Select one or more of the following:

  • en bloc modifications to the oligosaccharides, where a protein's modification is processed separately and one exchange occurs before exportation.

  • sequential modifications to the oligosaccharides, where each product is another enzyme's substrate.

  • varies different proteins' oligosaccharides.

  • uniforms different proteins' oligosaccharides.

Question 79 of 212

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A soluble protein sent to the Golgi can only be secreted.

Select one of the following:

  • True
  • False

Question 80 of 212

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Select the correct steps for processing of lysosomal enzymes by the Golgi:

Select one or more of the following:

  • Lysosomal proteins come to the Golgi with (Man)8(GlcNAc)2 oligosaccharide.

  • Lysosomal proteins come to the Golgi with (Man)3(GlcNAc)2 oligosaccharide.

  • 2 cis Golgi residents form the M6P.

  • 2 medial Golgi residents form the M6P.

  • M6P is an oligosaccharide.

  • N-acetylglucosamine phosphotransferase binds to lysosomal protein signal.

  • N-acetylglucosamine phosphotransferase catalyzes addition of phosphorylated GlcNAc group to carbon 6 of mannose on enzyme oligosaccharide.

  • GlcNAc phosphotransferase can mistakenly add M6P to secretory proteins.

  • Phosphodiesterase removes GlcNAc, leaving a phosphate.

  • Phosphodiesterase removes phosphate, leaving the oligosaccharide.

Question 81 of 212

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Select the possible destinations of proteins from the t-Golgi network.

Select one or more of the following:

  • PM via constitutive secretion.

  • PM via selective secretion.

  • PM via regulated secretion.

  • Lysosome via late endosome.

  • Lysosome directly.

  • PM directly.

  • ER via retrograde transport.

  • ER directly.

Question 82 of 212

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Regulated secretion:

Select one or more of the following:

  • involves release of a protein after a stimulus.

  • involves constant and direct secretion of a protein.

  • involves storing a protein in a vesicle for long term storage.

  • involves sending a protein directly to the PM.

  • involves nothing.

Question 83 of 212

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During protein-storing vesicle formation:

Select one of the following:

  • Proteins in vesicles from t-Golgi network aggregate before fusing with the target storage vesicle.

  • Proteins in vesicles fuse directly to the target storage vesicle without aggregation.

Question 84 of 212

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Studies show mammalian secretory cells contain:

Select one or more of the following:

  • Chromogranin.

  • Chromogranin A.

  • Chromogranin B.

  • Chromogranin I.

  • Chromogranin II.

Question 85 of 212

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The Chromogranin proteins in mammalian cells

Select one or more of the following:

  • aggregate only in storage vesicles.

  • aggregate in the t-Golgi network, but only with a pH of 6.5 and 1mM Ca2+.

  • aggregate in the t-Golgi network, but only with a pH of 5.5 and 1mM Ca2+.

  • may be basis for sorting secretory proteins either into regulated or constitutive secretion.

  • is not involved in sorting secretory proteins into regulated or constitutive secretion.

Question 86 of 212

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Proteins that do not associate with a Chromogranin aggregation:

Select one of the following:

  • will not be secreted.

  • will only be secreted from a storage vesicle.

  • will be carried to the PM for constitutive secretion.

  • Chromogranin aggregations do not bind with secretory proteins.

Question 87 of 212

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Proproteins of constitutive secreted proteins:

Select one or more of the following:

  • undergo proteolytic cleavage to form a mature, active protein.

  • undergo proteolytic cleavage in the t-Golgi network.

  • in mammalian cells are probably processed by furin.

  • in mammalian cells are probably processed by endoprotease PC2.

  • are cleaved once, at C-terminal dibasic sequence.

  • are cleaved once, at N-terminal dibasic sequence.

Question 88 of 212

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PC2 and PC3

Select one or more of the following:

  • are exoproteases.

  • act on proproteins for constitutive secreted proteins.

  • can help form insulin from proinsulin.

Question 89 of 212

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Insulin:

Select one or more of the following:

  • is cleaved to form N-terminal B chain and C-terminal A chain connected by disulfide bonds.

  • is a constitutive secreted protein.

  • probably has processing done by carboxypeptidase, which removes 2 basic aa residues.

Question 90 of 212

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Proteolytic processing is common because

Select one or more of the following:

  • keeps harmful enzymes from acting anywhere except its target organelle.

  • Peptides that are too large need to be contained in proproteins.

  • ex. enkephalins would not be synthesizable without proteolytic processing.

Question 91 of 212

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SNARE complex is stable because:

Select one or more of the following:

  • long alpha helices that coil to form a four alpha helix bundle.

  • long alpha helices that coil to form a two alpha helix bundle.

  • Hydrophobic residues at central core.

  • Hydrophilic residues at central core.

  • Alignment of aas of opposite charge forming favorable electrostatic interaction.

Question 92 of 212

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Clathrin:

Select one or more of the following:

  • mediates COPI and COPII vesicles.

  • mediates lysosomal enzyme transport vesicles.

  • are diskelions.

  • have three limbs.

  • polymerize to form polygonal lattice.

  • associates with AP complexes when monomer.

  • associates with AP complexes when polymerized.

Question 93 of 212

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Type of APs:

Select one or more of the following:

  • AP1, helps with t-Golgi network to endosome transport.

  • AP1, helps with PM to endosome transport.

  • AP2, helps with PM to endosome transport.

  • AP2, helps with endosome to t-Golgi network transport.

  • AP3, helps with t-Golgi network to lysosome transport.

  • AP3, helps with t-Golgi network to endosome transport.

Question 94 of 212

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AP1 interacts with:

Select one of the following:

  • KDEL.

  • KKXX.

  • YXXo.

  • DXLL.

  • DFGXo.

Question 95 of 212

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GGA is:

Select one of the following:

  • a new type of AP.

  • AP1.

  • AP2.

  • AP3.

  • a clathrin GTPase.

Question 96 of 212

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AP3:

Select one or more of the following:

  • can help deliver proteins to melanosomes in skin cells.

  • can help mediate protein transport to specialized compartments.

  • may not need clathrin for its vesicles to function.

  • helps vesicles bypass the late endosome.

Question 97 of 212

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GGA interacts with:

Select one or more of the following:

  • YXXo.

  • DXLL.

  • DFGXo.

  • Sec61.

Question 98 of 212

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Clathrin is needed for GGA vesicles.

Select one of the following:

  • True
  • False

Question 99 of 212

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All lysosomal vesicles utilize ARF GTPase to initiate coat assembly.

Select one of the following:

  • True
  • False

Question 100 of 212

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Dynamin is necessary for Clathrin coated vesicles to form.

Select one of the following:

  • True
  • False

Question 101 of 212

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Dynamin polymerizes around the neck of the vesicle bud and hydrolyzes ATP.

Select one of the following:

  • True
  • False

Question 102 of 212

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Dynamin:

Select one or more of the following:

  • hydrolyzes ATP.

  • hydrolyzes GTP.

  • helps COPI and COPII vesicles form.

  • works via conformational change that pinches vesicles.

Question 103 of 212

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Hsc70:

Select one or more of the following:

  • is a constitutive expressed molecular chaperone.

  • does not exist.

  • uses ATP hydrolysis.

  • uses GTP hydrolysis.

  • allows v-SNARE exposure and binding via Rab effector action.

  • allows t-SNARE exposure.

Question 104 of 212

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ARF hydrolyzes to have conformational change that regulates timing of clathrin depolymerization.

Select one of the following:

  • True
  • False

Question 105 of 212

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Select correct steps for transport of lysosomal enzymes to the lysosome:

Select one or more of the following:

  • M6P receptor binds in TGN.

  • pH must be 5.5 for M6P receptor to function.

  • ARF allows for coat assembly.

  • M6P receptor has YXXF.

  • M6P receptor has YXXo.

  • Dynamin does its thang.

  • Vesicle is uncoated via Hsc70.

  • Rab-GTP binds with Rab effector to facilitate SNARE interactions.

  • M6P receptor dissociates at lysosomal pH, and a phosphatase breaks up M6P.

  • Some M6P is then transferred to cell surface.

Question 106 of 212

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M6P is present at cell surface:

Select one of the following:

  • because it is sent there from the ER.

  • to release lysosomal enzymes into the ECM.

  • to retrieve lysosomal enzymes that were missorted.

Question 107 of 212

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Microphages can ingest:

Select one or more of the following:

  • 25% of own volume per hour.

  • 5% of PM per minute.

Question 108 of 212

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Phagocytosis:

Select one or more of the following:

  • is actin-mediated.

  • involves pseudopodia that surround target particle.

  • requires substances to transmit signals to inside of the cell.

  • is used by almost all cell types.

Question 109 of 212

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Fab regions:

Select one of the following:

  • recognize and bind infection organisms.

  • aid in pseudopodia development.

  • bind to other cells to mark as friendly.

Question 110 of 212

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Fc receptors allow phagocytic immune cells to target cells marked by Fab.

Select one of the following:

  • True
  • False

Question 111 of 212

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Receptor-mediated endocytosis:

Select one or more of the following:

  • involves clathrin-coated pits.

  • mostly utilizes AP1.

  • mostly utilizes AP2.

  • mostly utilizes AP3.

  • requires GTP hydrolysis to occur.

  • requires that receptors be recycled.

  • involves receptors that are freshly made from the Golgi.

Question 112 of 212

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The rate-limiting step of ligand internalization is:

Select one of the following:

  • number of receptors.

  • GTP concentration.

  • ATP concentration.

  • clathrin abundancy.

Question 113 of 212

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Ligands for receptor-mediated endocytosis include:

Select one or more of the following:

  • H2O

  • cholesterol carriers

  • erroneously sorted lysosomal proteins

  • protein hormones

  • transferrin

  • iron-binding proteins

Question 114 of 212

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Functions of cholesterol include:

Select one or more of the following:

  • maintain membrane fluidity.

  • fatty acid conversion.

  • synthesis of steroids.

  • killing heart tissue.

Question 115 of 212

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Water-soluble carriers for lipids called:

Select one of the following:

  • lipoproteins.

  • lipocholesterols.

  • lipocarriers.

  • McDonald's.

Question 116 of 212

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HDLs contain:

Select one of the following:

  • high levels of protein.

  • high levels of lipids.

  • high levels of cholesterol.

Question 117 of 212

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LDLs contain more ___ relative to HDLs.

Select one of the following:

  • proteins.

  • fats.

  • cholesterol.

Question 118 of 212

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Shell of LDL/HDLs composed of:

Select one or more of the following:

  • apolipoproteins.

  • polioproteins.

  • cholesterol-containing phospholipid monolayer.

  • cholesterol-containing phospholipid bilayer.

  • cholesterol-containing phospholipid trilayer.

Question 119 of 212

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LDL/HDL shell is amphipathic because:

Select one or more of the following:

  • outer hydrophilic surface.

  • inner hydrophilic surface.

  • outer hydrophobic surface.

  • inner hydrophobic surface.

Question 120 of 212

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LDL:

Select one or more of the following:

  • is the major cholesterol carrier.

  • carries more cholesterol than HDL.

  • has hydrophobic core with about 1500 esterified chol. molecules.

  • has only one apolipoprotein called apoA-100.

Question 121 of 212

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LDL-R:

Select one or more of the following:

  • has one TMD.

  • has two TMDs.

  • has long terminal N exoplasmic segment with ligand binding arm.

  • has long terminal C exoplasmic segment with ligand binding arm.

  • has binding arm with 7 cysteine-rich repeats of 40aa each.

  • has binding arm with 5 cysteine-rich repeats of 30aa each.

  • has YXXP signal.

  • has NPXY signal.

  • binds to AP-1.

  • binds to AP-2.

Question 122 of 212

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Select proper steps for LDL intake:

Select one or more of the following:

  • Neutral pH of cell surface allows apoB binding to LDL-R binding arm.

  • NPXY signal grabs AP-1 to form clathrin coat.

  • NPXY signal grabs AP-2 to form clathrin coat.

  • Dynamin hydrolyses GTP to pinch off vesicle.

  • Vesicle is shed with Hsc70's help. ARF-GTP to ARF-GDP.

  • Rab interaction allows for SNARE complex formation at pH of 5 at endosome.

  • At acidic endosome, histidine on LDL-R beta-propeller becomes (+).

  • Ligand binding arm now binds to LDL-R beta propeller.

  • LDL is released.

Question 123 of 212

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In lysosome, LDL:

Select one or more of the following:

  • has apoB hydrolyzed by protease.

  • has cholesterol esters exposed to cholestryl esterases.

Question 124 of 212

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Microvilli are composed of:

Select one of the following:

  • actin

  • MTs

  • intermediate filaments

Question 125 of 212

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Aggregations of small soluble subunits of cytoskeleton fibers are:

Select one or more of the following:

  • polymers.

  • protofilaments.

  • complete structures.

  • monomers.

  • dimers.

  • held together by strong covalent bonds, allowing for strength of the cytoskeleton.

  • held together by weak non-covalent bonds, allowing flexibility.

Question 126 of 212

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Protofilaments:

Select one or more of the following:

  • must avoid breaking from mere thermal motion.

  • form lateral connections with adjacent protofilaments.

  • assemble/disassemble only at the ends.

  • can assemble/disassemble in the middle.

  • of intermediate filaments form alpha helix coiled coils.

  • of actin and MTs are formed from globular monomers.

Question 127 of 212

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Microfilaments:

Select one or more of the following:

  • are the thinnest structures.

  • measure at 7 nm in width.

  • support the shape of the cell.

  • are made of actin monomers that form 3 chains that twist around each other.

Question 128 of 212

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G-actin:

Select one or more of the following:

  • has ATP binding site in cleft (facing (-) end) in center.

  • has a distinct polarity +/-.

  • has polarity due to electroactive aa side chains.

Question 129 of 212

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The plus end of an actin subunit polymer:

Select one or more of the following:

  • is positively charged.

  • is barbed.

  • is pointed.

  • breaks down and builds up rapidly.

  • changes rather slowly.

Question 130 of 212

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A lag is seen at the beginning of actin subunit interaction because:

Select one of the following:

  • nucleation must occur, which is a slow process.

  • subunits at the plus end are competing for space.

  • ATP hydrolysis takes time to occur.

Question 131 of 212

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Adding a nucleated actin segment:

Select one of the following:

  • worsens lag time.

  • eliminates lag time.

  • doesn't have an effect.

Question 132 of 212

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Catalysts of nucleation:

Select one or more of the following:

  • allow nucleation to occur quicker.

  • allow structures to build anywhere.

  • target structures to areas needed by the cell.

Question 133 of 212

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Actin nucleation is often regulated:

Select one of the following:

  • by external signals.

  • by genes.

  • by evil scientists.

Question 134 of 212

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Nucleation catalyzation can occur from:

Select one or more of the following:

  • ARF.

  • KDEL.

  • ARP2/3.

  • Formin.

  • Furin.

Question 135 of 212

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Formins:

Select one or more of the following:

  • help catalyze nucleation.

  • capture 2 actin molecules to begin nucleation.

  • dimerize.

  • continue to associate with actin at the plus end.

  • dissociate after nucleation.

Question 136 of 212

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ARP2/3:

Select one or more of the following:

  • is structurally similar to actin.

  • has a different plus end compared to actin.

  • allows actin monomers to bind at plus end.

  • remains bound to (-) end of actin polymer.

  • needs an activating factor to free it from accessory proteins that hold its active site out of orientation.

  • is most efficient at a 70 degree angle to preformed actin filament.

  • is associated with leading edge of migrating cells to allow cellular direction change.

Question 137 of 212

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Actin can hydrolyze its bound ATP:

Select one of the following:

  • anytime at the same rate.

  • quicker when in a filament.

  • quicker as a monomer.

  • never.

Question 138 of 212

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Actin-ADP is:

Select one or more of the following:

  • more likely to exist in a filament.

  • more likely to exist as a monomer.

  • more likely to dissociate from the filament.

  • less likely to dissociate from the filament.

Question 139 of 212

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If the rate of adding subunits to an actin filament is faster than the rate of ATP hydrolysis:

Select one of the following:

  • Now the filament has an ATP cap.

  • Now the filament has an ADP cap.

Question 140 of 212

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But, if the rate of subunit addition is low:

Select one of the following:

  • ADP hydrolysis occurs faster, allowing an ADP cap to form.

  • The world explodes.

Question 141 of 212

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Treadmilling:

Select one of the following:

  • makes me tired.

  • involves net addition at the minus end and net loss at the plus end simultaneously.

  • involves net addition at the plus end and net loss at the minus end simultaneously.

Question 142 of 212

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During treadmilling, the filament is changing length.

Select one of the following:

  • True
  • False

Question 143 of 212

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Thymosin:

Select one or more of the following:

  • binds to actin subunits, preventing binding to (+) or (-) end.

  • this is because thymosin blocks the area of the protein that hooks on to the filament.

  • thymosin blocks ATP binding site.

Question 144 of 212

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Profilin:

Select one or more of the following:

  • decreases rate of elongation.

  • binds to plus side of actin monomer.

  • favors hydrolysation of ATP to ADP.

  • is thought to bind to some formins to "stage" for action on the polymer.

Question 145 of 212

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Regulation of thymosin and profilin affect overall actin filament formation.

Select one of the following:

  • True
  • False

Question 146 of 212

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Cofilin:

Select one or more of the following:

  • binds filaments forcing tight twisting in the structure.

  • helps add monomers to the plus end of the filament.

  • weakens the contacts between subunits.

  • makes actin-ADP dissociation easier.

  • makes actin-ATP association easier.

  • binds preferentially to actin-ADP units.

  • destroys new filaments moreso than old ones.

  • has effects blocked by tropomyosin.

  • increases rate of disassembly.

Question 147 of 212

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Capping proteins stabilize ends of filaments.

Select one of the following:

  • True
  • False

Question 148 of 212

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Capping proteins are made where actin must be stable for long periods of time, like muscle cells.

Select one of the following:

  • True
  • False

Question 149 of 212

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Microfilaments are necessary for:

Select one or more of the following:

  • cytokinesis.

  • cleavage furrow.

Question 150 of 212

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Microtubules are the thickest of the cytoskeletal structures at 30nm.

Select one of the following:

  • True
  • False

Question 151 of 212

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MTs are hollow and built from:

Select one of the following:

  • 11 parallel protofilaments.

  • 13 parallel protofilaments.

  • 15 parallel protofilaments.

Question 152 of 212

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An MTOC:

Select one or more of the following:

  • is a microtubule organizing center.

  • is a centrosome in mammalian cells.

  • is on each end of a MT.

Question 153 of 212

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MTs determine the position of cytoplasmic organelles including vesicles.

Select one of the following:

  • True
  • False

Question 154 of 212

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MTs direct movement of chromosomes during cell division.

Select one of the following:

  • True
  • False

Question 155 of 212

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Tubulin:

Select one or more of the following:

  • is a heterodimer.

  • is composed of 3 globular proteins, alpha, beta, gamma subunits.

  • has its globular proteins held together via noncovalent bonds.

  • has alpha and beta subunits.

  • has two nucleotide binding domains for GTP (alpha, beta).

  • GTP is bound at the intersection between the alpha and beta subunits, and can be hydrolyzed.

  • GTP is bound to the beta subunit, and can be hydrolyzed by the beta subunit itself.

  • Alpha subunit is a GTPase.

Question 156 of 212

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What kind of contacts occur between tubulin subunits?

Select one or more of the following:

  • lateral

  • longitudinal

  • these contacts allow MTs to be stiff

Question 157 of 212

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MT alpha subunits are exposed at the minus end.

Select one of the following:

  • True
  • False

Question 158 of 212

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MT beta subunits exposed at minus end.

Select one of the following:

  • True
  • False

Question 159 of 212

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MT elongation involves:

Select one or more of the following:

  • tubulin-GTP binding to the plus end.

  • tubulin-GTP hydrolysis to tubulin-GDP while part of the filament.

  • tubulin-GDP causes curvature to form, weakening MT structure.

  • GTP caps can be formed if polymerization is faster than GTP hydrolyzation.

Question 160 of 212

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Dynamic instability has:

Select one or more of the following:

  • shrinking phase called catastrophe.

  • growing phase called rescue.

Question 161 of 212

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MT are nucleated at centrosomes.

Select one of the following:

  • True
  • False

Question 162 of 212

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A centrosome:

Select one or more of the following:

  • has a pair of centrioles.

  • is composed of fibrous centrosome matrix.

  • has about 50 gamma tubulins.

  • divides during interphase to aid with mitosis.

  • has many proteins in the matrix, that catalyze addition of tubulins.

Question 163 of 212

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Gamma tubulin:

Select one or more of the following:

  • is more abundant than alpha and beta units.

  • is involved in nucleation.

Question 164 of 212

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Gamma tubulin ring complex (gamma TuRC):

Select one or more of the following:

  • is formed from gamma tubulin and other proteins.

  • allows nucleation to occur.

  • binds the plus end of tubulin subunits to its minus end.

  • caps the minus end of the MTs.

Question 165 of 212

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Stathmins:

Select one of the following:

  • bind to tubulin subunits to prevent binding to the polymer.

  • facilitate tubulin binding to the polymer.

  • cap the end of the MT to prevent subunit binding.

Question 166 of 212

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MAPs (MT associated proteins):

Select one of the following:

  • prevent binding of subunits to the polymer.

  • bind to the polymer to stabilize.

  • bind to subunits to prevent interaction with the polymer.

Question 167 of 212

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Kinesin 13:

Select one or more of the following:

  • has motor activity.

  • attaches to the end of the MT to create a stabilizing cap.

  • pries apart the end of a MT.

  • does not interact with the end of the MT.

Question 168 of 212

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XMAP215

Select one or more of the following:

  • allows anaphase to occur.

  • can stabilize MT ends.

  • can be phosphorylated to be deactivated.

  • is not a MAP.

Question 169 of 212

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TIPs:

Select one or more of the following:

  • are plus end tracking proteins.

  • are plus end tubulin proteins.

  • can attach and stabilize the growing MT to different locations in the call.

  • accumulate and remain attached at the plus end.

Question 170 of 212

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Intermediate filaments:

Select one or more of the following:

  • are about 10 nm in width.

  • are the thickest filaments.

  • are required for correct cell functioning.

  • can have varied compositions.

  • are constructed only from a particular protein subunit.

  • can be constructed from keratin, vimentin, lamins, etc.

Question 171 of 212

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IMs can attach to cell junction proteins.

Select one of the following:

  • True
  • False

Question 172 of 212

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IMs are:

Select one or more of the following:

  • strong.

  • weak.

  • brittle.

  • bendable.

  • easy to break.

  • difficult to break.

Question 173 of 212

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Why are IMs unique?

Select one or more of the following:

  • different monomers.

  • assemble in nonpolar fashion.

Question 174 of 212

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IM structure:

Select one or more of the following:

  • two monomers form coiled-coil dimer.

  • each monomer has globular domain at each N & C terminus.

  • monomers have small, short alpha helical structure.

  • 10 protofilaments made up of pentamers form intermediate filament.

  • 8 protofilaments made up of tetramers form intermediate filament.

Question 175 of 212

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Strong lateral connections give IFs rope-like character.

Select one of the following:

  • True
  • False

Question 176 of 212

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IFs:

Select one or more of the following:

  • outer skin layer made of keratin that functions as a barrier.

  • support and anchor structures to maintain shape.

  • line the outside of the lining of the nuclear envelope.

  • provide strength to long axons of neurons.

Question 177 of 212

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Different cytoskeletal filaments have different motor proteins.

Select one of the following:

  • True
  • False

Question 178 of 212

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Myosin moves on:

Select one of the following:

  • actin, toward (+)

  • actin, toward (-)

  • MT, toward (+)

  • MT, toward (-)

Question 179 of 212

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Myosin:

Select one or more of the following:

  • is a large family of 37+ motor proteins.

  • typically refers to myosin II.

  • are all (-) end-directed.

  • is a two-headed dimer.

  • has alpha helices that form a coiled-coil tail.

  • has two small chains.

Question 180 of 212

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Coiled coils of myosin:

Select one or more of the following:

  • have heptad (7) aa repeat sequence.

  • have hydrophobic side chain interactions on 1st and 4th amino acids.

  • have hydrophobic side chain interactions on 2nd and 4th amino acids.

  • hydrophobic side chains weakly bind to form a superhelix.

Question 181 of 212

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Myosin thick filaments:

Select one or more of the following:

  • are formed by bundles of myosin motor proteins that form a polar contractile unit.

  • have a bare zone in the middle of the filament that has no myosin.

  • has myosin going one way on one side and another way on the opposite side.

  • myosin III is used to make myosin thick filaments.

Question 182 of 212

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Muscle contraction occurs because:

Select one of the following:

  • myosin shortens.

  • myosin and actin slide past each other.

  • myosin and actin shorten.

  • myosin filaments slide past each other.

Question 183 of 212

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Long thin muscle fibers:

Select one or more of the following:

  • are actually very large single cells.

  • are several cells lined up on a filament.

  • have majority of cytoplasm made up of myofibrils.

  • have most of cytoplasm filled with mitochondria.

  • have contractile units called sarcomeres.

Question 184 of 212

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Sarcomeres:

Select one or more of the following:

  • are arrays of parallel and overlapping thick (myosin) and thin (actin) filaments.

  • span from Z disc to Z disc.

  • have capZ proteins that cap and stabilize myosin heads.

  • have capZ proteins that cap and stabilize actin heads.

  • span from Z disc to capZ to Z disc to capZ.

Question 185 of 212

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Tropomodulin:

Select one of the following:

  • caps actin on (-) end.

  • caps actin on (+) end.

  • caps myosin on (-) end.

  • caps myosin on (+) end.

Question 186 of 212

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Straitions seen in sarcomeres are:

Select one or more of the following:

  • dark bands of actin.

  • dark bands of myosin.

  • light bands of actin.

  • light bands of myosin.

Question 187 of 212

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Thick filaments during contraction:

Select one or more of the following:

  • walk towards Z disc.

  • walk towards bare zone.

  • are driven by ~300 myosin heads that each have.

  • are driven by ~30 myosin heads that each have.

Question 188 of 212

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Sarcomere shortens __% of length in __ time.

Select one of the following:

  • 10%, 1/50th second

  • 20%, 1/50th second

  • 10% 1/100th second

  • 20%, 1/100th second

Question 189 of 212

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Z disc caps (+) and (-) ends of actin.

Select one of the following:

  • True
  • False

Question 190 of 212

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M line is another descriptor of the "bare zone."

Select one of the following:

  • True
  • False

Question 191 of 212

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M-line contains:

Select one or more of the following:

  • myosin heads.

  • myosin coiled-coil tails.

  • actin filaments.

  • actin coiled-coil tails.

Question 192 of 212

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Nebulin:

Select one of the following:

  • binds to actin and spans the length of it. Acts like a molecular ruler.

  • binds to myosin and spans the length of it. Acts like molecular ruler.

  • binds to actin and connects end to Z disc. Acts like molecular spring.

  • binds to myosin and connects end to Z disc. Acts like molecular spring.

Question 193 of 212

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Which accessory protein binds to myosin and acts like a spring that spans from M line to the Z disk?

Select one of the following:

  • Titin

  • Nebulin

Question 194 of 212

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Troponin is complex of 3 polypeptides essential for beginning muscle ____________ made up of __________.

Select one of the following:

  • muscle contraction; Trop I, Trop T, Trop C.

  • muscle contraction; Trop I, Trop T, Trop R.

  • muscle relaxation; Trop I, Trop T, Trop C.

  • muscle relaxation; Trop I, Trop T, Trop R.

Question 195 of 212

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Tropomysin binds:

Select one of the following:

  • along the groove of actin helix.

  • along the groove of myosin helix.

Question 196 of 212

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In absence of Ca2+, Troponin I binds to Troponin T to make I-T complex.

Select one of the following:

  • True
  • False

Question 197 of 212

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Troponin IT complex formation:

Select one of the following:

  • pulls tropomyosin out of groove.

  • allows tropomyosin back into the groove.

  • hydrolyzes tropomyosin.

  • phosphorylates tropomyosin.

Question 198 of 212

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Which troponin binds to tropomyosin:

Select one of the following:

  • I

  • T

  • C

Question 199 of 212

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Muscle contraction steps:

Select one or more of the following:

  • SR releases Ca2+ which binds to Troponin C.

  • Tropomyosin moves out of its groove.

  • Myosin head can now bind to actin after ATP binding.

  • Myosin head can now bind to actin after GTP binding.

  • Binding and hydrolysis of ATP/GTP causes conformational change in converter domain.

  • Swinging of lever arm causes head to move along actin.

Question 200 of 212

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Let's start with contraction just ended:

Select one or more of the following:

  • Myosin is attached to actin microfilament without a nucleotide.

  • Head is at 45 degree angle to filament.

  • Head is at 60 degree angle to filament.

  • ATP quickly binds and causes a conformational change in lever arm.

  • Myosin dissociates from actin.

  • As Ca2+ is taken up into SR by calcium P pump, Troponin I & T form IT complex.

  • ATPase myosin activity cleaves ATP to ADP and Pi.

  • Conformational change causes lever arm to swing 90 relative to filament, binds to actin.

  • Inorganic phosphate released, causing lever arm to return to 45 degree angle (the power stroke).

  • Myosin head loses ADP.

Question 201 of 212

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Rigor mortis:

Select one or more of the following:

  • begins a few hours after death and dissapates 48-60 hours after death.

  • is caused by a lack of ATP.

  • involves myosin being "stuck" in position.

  • dissipates after thermal energy causes myosin to break down.

  • ends when enzymes involved in degradation break down myosin heads.

  • is sped up by cold.

Question 202 of 212

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Kinesin:

Select one or more of the following:

  • is a motor protein.

  • mostly move vesicles and organelles toward the (-) end of MTs.

  • commonly refers to Kinesin II.

  • has a heavy chain on N terminus, the motor domain.

  • is involved in superfamily of at least 14 members.

Question 203 of 212

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Which region of kinesin has conformational changes during ATP binding and hydrolysis?

Select one of the following:

  • binder domain.

  • linker region.

  • either motor head domain.

  • alpha helical tail.

Question 204 of 212

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Kinesin C terminus holds cargo.

Select one of the following:

  • True
  • False

Question 205 of 212

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Has a similar function and a similar sequence to myosin II.

Select one of the following:

  • True
  • False

Question 206 of 212

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Select the steps of mechanochemical kinesin cycle:

Select one or more of the following:

  • Heads work in walking motion fueled by ATP.

  • Kinesin is typically bound to ADP, which will bind weakly to MT once contact made.

  • Kinesin-ADP becomes Kinesin-ATP.

  • Kinesin ATP will bind weakly to MT. Conformational change of ATP binding causes lagging strand to zip forward 8nm.

  • ATP hydrolyzed at on new lagging head.

  • New leading strand releases ADP and binds ATP with MT.

  • Lagging strand propelled forward.

  • Cool note. MT bound tightly by kinesin ATP, just like myosin II binds tightly to actin without nucleotide.

Question 207 of 212

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Dynein:

Select one or more of the following:

  • moves vesicles and organelles towards the center of the cell.

  • is involved in separation of chromatids during anaphase.

  • includes cytoplasmic dynein with 2 large head motor domains and 2 light domains.

  • includes complex axonemal dynein with 3 large heads and many light chains.

  • are the slowest motor proteins.

Question 208 of 212

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Dynein function:

Select one or more of the following:

  • large motor head in a ring at C terminal domain.

  • has 6 AAA domains, 4 of which retain ATPase activity with one primary.

  • has tail that carries cargo.

  • has long coiled-coil stalk that binds MT.

  • ATP hydrolysis causes attachment of stalk to MT.

  • release of ADP and Pi leads to the large power stroke conformational change.

  • 8nm steps toward (-) of MT.

Question 209 of 212

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Kinesin directs vesicles and organelles to cell exterior.

Select one of the following:

  • True
  • False

Question 210 of 212

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Cdc42 yields large number of filopodia made of MTs.

Select one of the following:

  • True
  • False

Question 211 of 212

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Rac, Rho, cdc42 are small G proteins that alter actin skeleton.

Select one of the following:

  • True
  • False

Question 212 of 212

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Taxol kills rapidly dividing cells by stabilizing MTs.

Select one of the following:

  • True
  • False
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Cell Bio - Exam 2

Ryan Pappal
Quiz by , created about 2 years ago

Quiz on Cell Bio - Exam 2, created by Ryan Pappal on 19/10/2014.

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Ryan Pappal
Created by Ryan Pappal about 2 years ago
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