1) The phosphorylation of eIF2 and eIF2B leads to: a) Increased translation efficiency b) Inhibition of translation initiation c) Enhanced ribosome assembly d) Faster protein folding 2) The Iron Response Element (IRE) regulates ferritin translation by: a) Recruiting additional ribosomes to the 5′ end b) Binding IRP proteins to block 40S ribosome binding c) Enhancing miRNA binding at the 3′ UTR d) Activating proteasome-mediated degradation 3) Molecular chaperones function primarily by: a) Directly catalyzing peptide bonds b) Preventing incorrect protein folding c) Cutting misfolded proteins into peptides d) Phosphorylating serine and threonine residues 4) Which modification anchors proteins to the cell membrane via glycolipids? a) Glycosylation b) Lipid addition (GPI anchor) c) Proteolysis d) Phosphorylation 5) Which enzyme removes phosphate groups from proteins? a) Protein kinase b) Protein ligase c) Protein phosphatase d) Protein synthetase 6) Ubiquitin tags proteins for degradation by: a) The lysosome b) The proteasome c) The Golgi apparatus d) Ribosomal subunits 7) Which stage of the cell cycle is regulated by cyclin B degradation? a) G1 → S transition b) Prophase initiation c) Passage through metaphase d) Cytokinesis 8) Alzheimer’s disease is characterized by: a) Misfolded insulin proteins b) Amyloid plaques and tau tangles c) Defective ribosome assembly d) Lack of ubiquitin recycling 9) A mutation prevents eIF2 from being phosphorylated under stress conditions. Which outcome is most likely? a) Translation continues even during stress b) Translation halts permanently c) eIF4E cannot bind the 5′ cap d) Ubiquitin accumulates in the cytoplasm 10) A researcher deletes the ubiquitin ligase E3. What will happen to protein degradation efficiency? a) No effect, because E1 and E2 still function b) Degradation slows because target proteins cannot be recognized c) Degradation speeds up due to accumulation of polyubiquitin d) Cyclin B breakdown is unaffected 11) If a mutant miRNA perfectly complements its target mRNA, what is the most likely result? a) Increased translation b) Degradation of the mRNA c) Blockage of ribosome recycling d) Disruption of chaperonin function 12) A mutation blocks proteolytic cleavage of proinsulin. What effect would this have on insulin production? a) Functional insulin would not be produced b) Insulin would be secreted earlier than normal c) Insulin would contain excess glycosylation d) There would be no effect on insulin function 13) Which experimental outcome would confirm that a protein is degraded by the proteasome? a) Protein levels increase in the presence of proteasome inhibitors b) Protein levels decrease in the presence of proteasome inhibitors c) Protein phosphorylation decreases when ATP is absent d) Protein folding improves when chaperones are inhibited 14) Which of the following are outcomes of phosphorylation of eIF2 under stress conditions? a) Inhibition of translation initiation b) Recycling of GDP to GTP is blocked c) Ribosome assembly is enhanced d) Global protein synthesis is reduced 15) Which of the following are functions of molecular chaperones? a) Prevent incorrect protein folding b) Catalyze peptide bond formation in ribosomes c) Assist proteins during transport into organelles d) Stabilize unfolded polypeptides 16) Which of the following are true about ubiquitin and the proteasome? a) Ubiquitin is highly conserved across eukaryotes b) E3 ligase confers substrate specificity c) Polyubiquitylated proteins are degraded into peptides d) Ubiquitin is destroyed along with the protein 17) Which modifications can alter protein localization? a) N-myristoylation b) Prenylation c) Glycosylation d) Palmitoylation 18) Which of the following diseases are associated with protein misfolding or aggregation? a) Alzheimer’s disease b) Parkinson’s disease c) Cystic fibrosis d) Creutzfeld-Jakob disease 19) Which statements about Ras are correct? a) Ras is active when bound to GTP b) Ras mutations are involved in about 30% of human cancers c) GAP proteins promote Ras activation d) GEFs promote exchange of GDP for GTP

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