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Exam 2: 1. Most microtubules in a cell originate from a specific intracellular location called the a. Centrosome b. Sarcomere c. Centromere d. ARP complex 2. Which of the following cytoskeletal motor proteins generally move toward the minus end of the filament? a. Myosin-I b. Myosin-II c. Dynein d. Kinesin-I 3. If a myosin-II filament is placed between two parallel (not anti-parallel) actin filaments, it will cause the actin filaments to slide past each other. a. True b. False 4. Cofilin a. Stabilizes the hydrolyzed end of an actin filament b. Accelerates de-polymerization of the hydrolyzed end of an actin filament c. Serves to cap the growing end of the actin filament d. Is an example of nucleating proteins 5. Membrane proteins can be bonded covalently to lipids a. True b. False 6. Which of the following statements is true about myosins? a. Myosins can have more than one head domain b. Myosin-I self assembles to form myosin filaments c. Only one of the two heads of myosin-II can bind to nucleotides d. Myosin-V has five head domains 7. During muscle cell contraction a. Z-discs move closer to each other b. The myosin filament shrinks c. The actin filament shrinks d. Z-discs move away from each other 8. Which of the following could be affected by a mutation in the actin protein? I. Mitosis II. Cellular shape III. Muscle Contraction a. I b. I and III c. II and III d. I, II, and III 9. Which of the following is true about nucleotides bound to actin monomers? a. Their hydrolysis increases affinity between two monomers b. Their hydrolysis decreases affinity between two monomers

c. ADP-to-ATP exchange occurs when the monomers is part of the filament d. ATP-to-ADP exchange occurs when the monomer is part of the filament 10. Intermediate filaments in two epithelial cells can be linked to each other through a cellcell junction a. True b. False 11. Activation of RhoA GTPase in cells a. Increases formation of stress fibers b. Decreases formation of stress fibers c. Decreases myosin activity d. Induces formation of lamellipodium 12. ATP binding to Myosin-II head a. Causes the Myosin-II head to attach to the actin filament b. Produces the power stroke for Myosin-II to move on the actin filament c. Causes the myosin-II head to detach from the actin filament d. Cause ADP to release from the myosin-II head 13. During muscle contraction, Ca++ ions in the muscle cell are needed for a. Muscle relaxation b. Hydrolyzing ATP in myosin-II heads c. Releasing tropomyosin from the myosin-binding sites on actin d. Opening Ca++ channels in the SR 14. Muscle cells are formed from fusion of many precursor muscle cells called a. Myoblasts b. Glial cells c. Schwaan cells d. Epithelial cells 15. A person who carries blood group O can donate blood to a person who carries a. Blood group A, but not to a person who carries blood group AB b. Blood group AB, but not a person who carries blood group A c. Blood group O, but not to a person who carries blood group AB d. Any of the three blood groups, A, AB or O 16. Which of the following processes take place in a crawling cell? a. Actin polymerization b. Actin de-polymerization c. Actin-myosin contraction d. All of the above 17. What is the process by which action potentials are able to “jump” from one node of Ranvier to another? a. Repolarization b. Salutatory conduction c. Depolarization d. Hyperpolarization 18. Which of the following is true about NaK pump? a. For each molecule of ATP hydrolyzed inside the cell, it transports 3 NA+ ions outside the cell and 2 K+ ions inside the cell b. It does not help in maintaining electrical potentials across plasma membranes

c. For every 2 molecules of ATP hydrolyzed inside the cell, it transports 3 Na+ ions inside the cell and 2 K+ ions outside the cell d. It does not help in regulating cell volume 19. Which of the following is an example of active transporter? a. Na+ coupled glucose transporter b. Voltage gated Na+ channel c. Delayed rectifier K+ channel d. Acetylcholine receptor channel 20. A mutation is discovered that results in the myelin sheath overgrowing and covering all the space along the axon where there would normally be Nodes of Ranvier. Which of the following would be expected of such a neuron? a. Close to normal functioning b. Repeated spontaneous signal transmission down the axon c. Inability to be stimulated by action potential d. Inability to propagate an action potential down the axon 21. The action potential does not reverse direction on its own because a. The voltage gates K+ channels are in their open state b. The voltage gated Na+ channels cannot transition directly from inactive to open states c. The voltage gated Na+ channels are in their inactivated states d. The delayed rectifier K+ channels cannot transition directly from inactive to open states 22. Neurotransmitters that open Cl- channels in the post synaptic cell membrane a. Depolarize the post synaptic cell membrane b. Do not affect the electrical potential of the post synaptic cell membrane c. Produce a similar effect as neurotransmitters that open K+ channels in the post synaptic cell membrane d. Are called excitatory neurotransmitters 23. At physiological pH, the head-group of phosphatidyl-serine a. Has the same charge as the head-group of phosphatidyl-choline b. Has a net neutral charge c. Has a net positive charge d. Has a net negative charge 24. The role of Na+-glucose symporters in the epithelial cells lining of the gut is to a. Bring glucose into the epithelial cell against the concentration gradient of Na+ b. Bring glucose into the epithelial cell against the concentration gradient of glucose c. Release glucose into the extracellular fluid d. Bring glucose into the epithelial cell using the energy provided by ATP hydrolysis 25. Sown below is a trace of current passing over time through a membrane patch

a. there are more than 2 channels in the membrane patch b. there are at least 2 channels in the membrane patch

c. there is only one channel in the membrane patch d. the membrane patch is defective 26. The compositional asymmetry of plasma membranes is a. Regulated by Flippases b. Regulated by scramblases c. Not regulated by any enzyme d. Not important to cellular function 27. The rate of fluorescence recovery in FRAP informs us of how fast lipids a. Rotate b. Diffuse c. Flex d. Flip-flop 28. The permeability of a lipid bilayer for glucose ions is 10 -8 cm/sec. Consider a cell whose glucose transporter is knocked out. If it is placed in a solution that contains 10mM glucose, how many glucose molecules will enter the cell in 1 second? Assume that the cell contains no glucose and the surface area of its plasma membrane is 10 um2? a. 6 b. 60 c. 600 d. 6000 29. Which of the following statements is true about passive transport of ions across membranes? a. Passive transport requires energy from ATP hydrolysis b. Passive transport always occurs against concentration gradients of ions c. Passive transport can occur at rates faster than those predicted by Fick’s law d. Passive transport is carried out by channels, but not transporters 30. Ca++ pumps in the SR of muscle cells a. Restore Ca++ conc in the SR after muscle contraction b. Restore Ca++ conc in the cytoplasm of the muscle cell after muscle contraction c. Import 2 Ca++ ions into the SR in exchange for 1 proton d. Export 1 Ca++ ions into the SR in exchange for 2 protons 31. Which of the following is an example of an excitatory neurotransmitter? a. GABA b. Ca++ c. Glycine d. Glutamate 32. Myelination of axons a. Increases the rate of nerve conduction b. Slows down nerve conduction c. Does not affect the rate of nerve conduction d. Increases number of NAK pumps in the axon plasma membrane 33. The pharmaceutical drug Taxol kills dividing cells by a. Stabilizing microtubules b. Destabilizing microtubules c. Stabilizing actin filaments d. Destabilizing actin filaments

34. The opening of _________ at the synaptic junction causes neurotransmitter secretory vesicles to fuse with the pre-synaptic membrane. a. NaK pumps b. Voltage gated Na+ channels c. Voltage gated Ca++ channels d. Glutamate receptor channels 35. Which of the following statements is true about neurons? a. Neurons employ a passive signaling mechanism in which the signal is not amplified along b. A single neuron in the CNS can receive inputs from hundreds of other neurons c. While axons generally receive signals, dendrites transmit them d. An action potential carries a signal from one end of the neuron to another at speeds of about 100 millimeters per second 36. All antimicrobial peptides a. Are small hydrophobic molecules b. Are produced as part of the innate immune response c. Translocate across the bacterial plasma membrane d. Increase the permeability of bacterial plasma membrane 37. A functioning H+ pump in the lysosome membrane will decrease the concentration of H+ inside the lysosome a. True b. False 38. Dynamic instability a. Refers to the phenomenon in which the plus end of the filament grows and the minus end of the filament shrinks b. Enables rapid rearrangement of the cytoskeleton c. Refers to the rapid growth of microtubules in the absence of a GTP tubulin cap d. Refers to the rapid shrinkage of microtubules in the presence of a GTP tubulin cap 39. The location. Length, and diameter of microvilli on intestinal epithelial cells are maintained throughout the life of the cells a. True b. False 40. Which of the following is true about intermediate filaments? a. The subunit of an intermediate filaments is a dimer b. The intermediate filament polymerizes preferentially toward the plus end c. The intermediate filament form stable structures and cannot be dissembled by biological stimuli d. Nuclear lamins are a kind of intermediate filament that disassemble during mitosis 41. The concentration of K+ ions inside a typical mammalian cell is a. Lower than the conc of K+ ions outside the cell b. Higher than the conc of K+ ions outside the cell c. Similar to the conc of Na+ ions inside the cell d. Less than 1 micro molar 42. The wave-like motion of flagellum is produced by the movement of

a. b. c. d.

Kinesins on actin filament Kinesin on microtubule Dynein’s on microtubule Dynein’s on actin filament

Exam 3: 1. The low pH inside endosome a. Destroys internalized cargo proteins b. Destroys internalized receptors c. Causes internalized receptors to release their cargos d. Causes cargo proteins to bind to their receptors 2. Which of the following choices reflects the appropriate order through which a protein destined for the plasma membrane travels upon synthesis? (CGN: cis golgi network; TGN: trans golgi network) a. ER  CGN  TGN  plasma membrane b. ER  TGN  CGN  plasma membrane c. ER  endosome  plasma membrane d. ER  lysosome  plasma membrane 3. The ER signal sequence on a growing polypeptide chain is recognized by a signal recognition particle in the cytosol. This interaction: a. Causes the polypeptide chain to dissociate from the ribosome b. Causes the ribosome to return to the pool of free ribosome in the cytosol c. Guides the ribosome and its polypeptide to an ER membrane d. Speeds the synthesis of the polypeptide chain 4. The purpose of the unfolded protein response (UPR) in the ER is to: a. Ensure that the proteins that entered the ER are exported to the Golgi as rapidly as possible b. Ensure that all the proteins in the ER are properly folded before being exported c. Enhance the translation rates to facilitate protein import into the ER 5. Which of the following statements concerning moving a protein from the nucleus to the cytosol is incorrect? a. A sorting signal in the cargo protein binds to the nuclear import receptor b. Transport utilizes GTP as the energy source c. Folded cargo proteins must be unfolded before being transported d. A nuclear import receptor must be able to travel in and out through the nuclear pore 6. Which of the following proteins would be transported to the ER lumen upon synthesis off a. Histones b. Insulin c. Lysosomal hydrolase d. B and c 7. Which of the following descriptions about microRNA (miRNA) is correct? a. miRNAs target DNA molecules for degradation

b. A single miRNA can target multiple mRNAs, If all the mRNAs carry a common target sequence c. Unlike other non-coding RNAs, miRNAs do not require processing once initially synthesized 8. Choose one of the below anticodon sequence of the tRNA which would most likely basepair with codons specifying glutamic acid (Glu). a. 5’-GAA-3’ b. 5’-GAG-3’ c. 5’-CUU-3’ d. 5’-UUC-3’ 9. The sequence of nucleotides in the following DNA template strand a. C b. S c. I d. H 5’-GTAACGGCT-3’

10. Regulatory DNA sequences that are located large distances from the transcription start site and in stimulating gene expression are called _____. a. Activators b. TATA boxes c. Enhancers d. Operators 11. What is the definition of an operon? a. A short sequence of DNA to which a gene regulatory protein binds b. A set of genes found in bacteria that is transcribed into a single mRNA c. A gene that is controlled by binding to two or more gene regulatory proteins 12. A schematic of the 4 scenarios depicting whether the Lac Operon is ON or OFF. Which of the following is the situation when only glucose is available for bacteria?

a. A b. B c. C d. D 13. The Lac operon is the MOST active when: a. Both glucose and lactose are present

b. Glucose is present, but lactose is not c. Lactose is present, but glucose is not d. Neither glucose nor lactose are present 14. Proteasomes act primarily on proteins that have been marked for destruction by the covalent attachment of which small molecule? a. Phosphate b. Ubiquitin c. Acetyl group d. Protease 15. Which of the following statements is TRUE regarding insulin-producing pancreatic B cells? a. The ER in this cell type is predominantly smooth ER b. The vesicular secretory pathway is particularly active in this cell type c. Insulins are secreted primarily by constitutive secretion pathway d. All of the above are true 16. Which statement(s) accurately describe(s) the promoter of a gene? a. It is the place on the DNA where RNA polymerase binds b. It determines which DNA strand of a gene is used as a template c. It is the first region of DNA that is transcribed into RNA d. Both a and b 17. Below is the structure of a mature mRNA. What is the protein encoding region? (UAA is a stop codon

a. Between a and b b. Between a and c c. Between b and c d. Between a and d e. Between b and d 18. There is no known GTP-binding protein involved in the transportation process to this organelle A 19. Transport into this organelle is co-translational. C 20. A protein translocator moves the protein across both the organelle’s membranes simultaneously at a contact site; chaperone proteins help translocate the protein A a. Mitochondrion b. Nucleus c. ER d. Lysosome (through vesicles) 21.

Which protein plays a key role in catalyzing the fusion of a vesicle with a target membrane, following vesicle docking? a. Rab proteins b. Tethering proteins c. Clathrin proteins d. SNARE proteins 22. A “TATA box” is:

a. The translation termination sequence b. A transcription start site c. The site where the RNA polymerase II complex is assembled d. A translation start site 23. Eukaryotic cell can regulate gene expression at any step in the pathway shown in the diagram. In which step does ‘RNA processing’ control occur?

a. A b. B c. C d. D 24. Which of the above types of control is unlikely to be used in bacteria? a. A b. B c. C d. B, C, D e. B, C 25. What is the reason for the slower rate of replication fork movement in eukaryotes compared to that of prokaryotes? a. Proofreading activity differs between prokaryotes and eukaryotes b. Eukaryotic DNA contains introns c. Eukaryotic DNA is packed with nucleosomes d. The eukaryotic replication origins move in a bidirectional manner 26. Special structures called telomeres are needed in eukaryotic cells, but not in bacteria, because: a. Eukaryotic cells contain linear chromosomes b. Eukaryotic cells have more than one chromosome c. Eukaryotic cells contain a nucleus d. Eukaryotic cells contain more forms of DNA polymerase 27. In the absence of telomerase activity: a. The ends of chromosomes would lengthen b. The ends of chromosomes would shorten c. Chromosomes would not segregate to daughter cells during mitosis d. Replication of chromosomes would be inhibited 28. Which of the following statements accurately describes what has occurred in the figure?

a. A mismatch has occurred during DNA replication

b. DNA damage has resulted in a base pair deletion c. A mutation has resulted in a base pair change (substitution). 29. Which statement regarding sigma factor is true? a. Sigma factor recruits bacterial RNA Pol to promoter sequences b. Sigma factor must remain bound to RNA Pol throughout the entire transcription process c. Sigma factor forms a large complex with other general transcription factors to promote transcription d. All are true 30. In the Genetic code, there are: a. More nucleotides than codons b. More codons than amino acids c. The same number of codons and amino acids d. More tRNAs than codons 31. For the gene of the tryptophan operon to be expressed in bacteria, which of the following must occur to the Trp repressor? a. It must be broken down by hydrolysis b. It must bind to the operator of the gene c. It must be bound by trptophan d. It must cease binding with the operator 32. One way an activator might help to turn on a eukaryotic gene is by interacting with and stabilizing the transcription initiation complex; another way is by ______. a. Recruiting a histone octamer b. Recruiting a general transcription factor c. Recruiting a histone acetyltransferase 33. A specialized type of RNA polymerase used during DNA replication. E 34. Removes and replaces an RNA primer with DNA, then seals the break. D 35. Breaks hydrogen bond between base pairs during DNA replication. A a. Helicase b. Single stranded DNA binding protein (SSB) c. Topoisomerase d. Nuclease, DNA polymerase, and DNA ligase e. Primase 36. During DNA replication, which of the following processes requires the synthesis of an RNA primer? a. Leading strand synthesis only b. Lagging strand synthesis only c. Both leading strand synthesis and lagging strand synthesis d. RNA primers are not used for DNA synthesis 37. Which of the following is TRUE about replication origins? a. Eukaryotic chromosomes typically have one of them b. They are helpful, but not essential, for DNA replication c. They are rich in G-C base pairs d. They are rich in A-T base pairs 38. As the replication form progresses, which of the following proteins in the Replisome is the ‘front-..’ that moves ahead of the rest of the proteins?

a. DNA polymerase b. RNA primase c. Helicase d. Sliding clamp 39. The sequence below shows the 5’ end of a eukaryotic mRNA molecule. Based on the sequence given, which of the three possible reading frames would you expect to be used for translation? a. 5’-GGC l CAC l CAU l GGC l UGA l A… b. 5’-G l GCC l ACC l AUG l GCU l GAA… c. 5’-GG l CCA l CCA l UGG l CUG l AA… d. all tree frames are translated, and the erroneous polypeptides are broken down after they ate made 40. Which of the following is NOT a main role for the oligosaccharides on glycosylated proteins? a. They can protect the protein from degradation b. They can help misfolded polypeptides in the ER to be properly folded c. They can provide a source of energy for the cell 41. Dynamin plays an essential role in the formation of clathrin-coated vesicle. In the absence of Dynamin: a. Clathrin coats are not assembled at the membrane b. Cathrin coats are formed, but the coated vesicles do not pinch off from the membrane c. Clathrin coated vesicles bud off normally, but they are not able to fuse with targets 42. The statement below concerns the environment which cargo proteins are exposed to during vesicular transport. Is the below statement correct or incorrect? “In vesicular transport, the interior space (or lumen) of the ER is equivalent to the cell exterior” a. Correct b. Incorrect Exam 4: 1. GTP binding proteins, which act as molecular switches inside cells: a. Are active when GDP i...