BCMB 311 exam 2

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Mitochondria are small round organelles that are often associated with actin filaments of the cytoskeleton.
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Terms in this set (100)
It accounts for the majority of O2 uptake in most cells.cytochrome c oxidase complexIt employs the Q cycle to increase proton pumping.reductase complexIt contains separate modules for electron transport and proton pumping.NADH complexIt produces the sugar glyceraldehyde 3-phosphate.darkIt involves the electron-transfer chain embedded in the thylakoid membrane.lightIt involves O2 production.lightIt involves fixation of CO2.darkIt generates ATP.lightCarbon fixation in photosynthetic cells eventually generates glucose, the major form of sugar that is transported to other plant tissues.falsePlant cells can generate fat droplets in their chloroplasts using glyceraldehyde 3-phosphate.trueATP generated in the light cycle is the major source of ATP used by the plant cell to power all of its biochemical reactions.falsePlant cells can generate starch granules in their chloroplasts using glyceraldehyde 3-phosphate.truePyruvate is generated in the chloroplast by the glycolytic pathway.falseThe electrochemical gradient that drives ATP production is dominated by the electrical component.mitochondriaIt involves a significant pH difference across the membrane.chloroplastsThe ATP synthase molecules form dimers.mitochondriaThe ATP synthase molecules are distributed randomly in flat membrane regions.chloroplastsChloroplasts are thought to descend from ancient purple sulfur bacteria.falseMitochondria are thought to descend from ancient α-proteobacteria.trueThe first photosynthetic cyanobacteria evolved before the first aerobic proteobacteria.trueAll photosynthetic and aerobic bacteria are thought to have evolved from a common ancestor capable of fermentation and membrane electron transport.trueExtensive editing occurs on their RNAs.chloroplastsThey utilize dynamin-like GTPases to divide from the outside.mitochondriaThe organization of gene clusters in their genome is strikingly similar to cyanobacteria.chloroplastsThey typically have larger genomeschloroplastsThey have a more ancient endosymbiotic relationship with their host.mitochondriaIt has a higher percentage of noncoding DNA.nucleiIt has a stricter codon usage.nucleiIts genes are present at higher copy numbers per cellmitochondriaIts evolutionary clock ticks much faster.mitochondriaMost proteins in these organelles are encoded by the organelle's genome.falseMammalian mtDNA can make up less than 1% of the total cellular DNA.trueIn some highly specialized animal cells, mtDNA can comprise as much as 99% of the cellular DNA.trueThe genetic systems of these organelles are most similar to extremophilic archaea.falseRibosomesTE to cytosolchromatinTE to cytosollysosomal hydrolasesTE to extracellular spacecalcium ions in the ERTE to extracellular spaceperoxisomal catalaseTE to extracellular spaceImport into nucleusgated transportExport from nucleusgated transportImport into mitochondriatransmembrane transportReturn from Golgi to ERvesicular transportReturn from ER to cytosoltransmembrane transportAlmost all eukaryotic cells have plastids, but only plant cells have chloroplasts capable of photosynthesis.falseThe perinuclear space is topologically equivalent to the extracellular space.trueThe mitochondria and chloroplasts are thought to have evolved by invagination and pinching off from the plasma membrane of the ancient eukaryotic cell.falseAll organelles in a eukaryotic cell can be constructed de novo, which means that the information to construct them is encoded in the genome.falseThe inner and outer nuclear membranes are continuous with each other, yet maintain distinct protein compositions.trueThe outer nuclear membrane is studded with ribosomes engaged in protein synthesis.trueThe endoplasmic reticulum lumen is continuous with the nuclear interior.falseRibosomal proteins pass through the nuclear pore complexes twice; they are imported into the nucleus after synthesis, and are exported from the nucleus after assembly with ribosomal RNA.trueMany nuclear import and export receptors are members of the same protein family.trueMost nuclear import receptors contain unstructured domains with FG-repeats.falseAdaptor proteins that simultaneously bind to nuclear localization signals and to importins are required for the import of some nuclear cargo proteins.trueRan is mostly found in its GTP-bound form in the nucleus.trueMitochondrial proteins should fold natively twice: once in the cytosol and once inside the organelle.falseβ-barrel proteins that are abundant in the mitochondrial outer membrane are imported from the cytosol independently of the TOM complex.falseSignal sequences that target precursor proteins to the mitochondrial matrix form an α- helix in which positively charged residues cluster near its N-terminus, while uncharged or hydrophobic residues cluster near the other side.falseAt least two signal sequences are required to direct proteins to the mitochondrial matrix.falseIncorporation of new Tom40 in the outer membrane requires preexisting Tom40 in that membrane.trueFormation of new TOM complexes is dependent on the SAM complex.trueTom40 is partially translocated through the outer membrane and is then transferred in the plane of the membrane to fold into its native conformation.falseTom40 is translocated through the inner membrane as a precursor.falseATP and GTP hydrolysis drive translocation into the organelle.chloroplastsThe organelle has an extra compartment that requires extra signal sequences for protein targeting.chloroplastsTransport through the double membrane is driven in part by an H+ gradient across the inner membrane.mitochondriaImported precursor proteins have amphiphilic N-terminal signal sequences that are usually removed after use.bothHsp70 family chaperones inside the organelle assist in protein translocation during import.bothAll peroxisomal proteins are encoded in the nucleus.trueSome peroxisomal proteins are synthesized by ribosomestrueAll peroxisomal proteins reach the organelle after their synthesis is completed.truePeroxisomal proteins have to be unfolded before import.falseIt mostly has a tubular appearance.smooth ERIt contains the transitional ER.smooth ERIt is coated by ribosomes.rough ERIt can be specialized for functions such as detoxification and lipid metabolism.smooth ERSarcoplasmic reticulum in muscle cells is one of its specialized forms.smooth ERA single-pass transmembrane protein that has one N-terminal signal sequence and one internal stop-transfer signalc-terminusA single-pass transmembrane protein that has one internal signal sequence that is preceded by a patch of positively charged residuesn-terminusAn ER tail-anchored proteinn-terminusN-linked glycosylation can be carried out co-translationally, possibly at multiple asparagine residues on the same protein molecule.trueN-linked glycosylation is a gradual process, with step-by-step addition and trimming events that commence with the addition of N-acetylglucosamine to an asparagine side chain.falseMost proteins synthesized in the rough ER are N-glycosylated, and some of them require this modification for their correct folding.trueOnce a protein is properly folded in the ER, its attached oligosaccharides are quickly removed by an N-glycanase, although it may be glycosylated again later.falseAssembly of GlcNAc oligosaccharides on dolichol phosphatecystolic sideSynthesis of phosphatidylcholinecystolic sideSynthesis of sphingomyelingolgiUbiquitylation of misfolded ER proteincystolic sideSynthesis of phosphatidic acidcystolic side