MCB 150 FINAL EXAM PRACTICE QUESTIONS
MCB 150 FINAL EXAM PRACTICE QUESTIONS MCB 150
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This 19 page Study Guide was uploaded by Jessica Logner on Wednesday April 13, 2016. The Study Guide belongs to MCB 150 at University of Illinois at Urbana-Champaign taught by Bradley G Mehrtens in Summer 2015. Since its upload, it has received 408 views. For similar materials see Molecular and Cellular Biology in Biology at University of Illinois at Urbana-Champaign.
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Date Created: 04/13/16
MCB 150 FINAL PRACTICE QUESTIONS + ANSWERS Which of the following is not a cellular activity associated with microtubules? a. maintenance of axons b. maintenance of cell shape c. cytokinesis of animal cell d. axonemal structure e. formation of mitotic spindle c Microtubules have an inner diameter of ________ and an outer diameter of ________. a. 15 mm; 25 mm b. 8 nm; 12 nm c. 25 nm; 30 nm d. 15 nm; 25 nm e. 7 mm; 14 mm d Which stage of microtubule assembly is the stage in which nucleation occurs? a. sheets of protofilaments b. closing of microtubules c. oligomers d. dimers e. elongation c Which one of the following statements about microtubules is correct? Microtubules: a. require ATP hydrolysis for growth. b. are static structures within a cell. c. are made up of tubulin heterotetramers. d. are made up of 13 linear protofilaments. e. are symmetrical rather than polar structures. d Critical concentration is... a. the concentration of tubulin dimers at which assembly is balanced with disassembly. b. the concentration of tubulin dimers at which assembly occurs primarily. c. the concentration of Gactin in most muscle cells. d. required before nucleation can occur. e. both choices A and D a Which one of the following statements about dynamic instability of microtubules is correct? Dynamic instability: a. was first shown by Watson and Crick in 1952. b. describes the alternating cycles of growth and shrinkage in microtubules. c. describes the frequent cleavage of microtubules near the middle of its length. d. describes the growth of microtubules when the concentration of GTPbound tubulin is low. e. describes the behavior of the stock market in economics. b The minus () ends of microtubules are often anchored at the ________________ , such that the dynamics associated with microtubules is at the plus (+) ends. a. centriole b. centrosome c. plasma membrane d. centromere e. mitochondrial outer membrane b Which motor protein(s) can move cargocontaining vesicles along microtubule tracks? a. Kinesin only b. Myosin and dynein c. Kinesin and myosin d. Kinesin and dynein d The cilia and flagella of eukaryotic cells are composed of _____. a. microfilaments b. pili c. tonofilaments d. intermediate filaments e. microtubules e Centrioles, cilia, flagella, and basal bodies have remarkably similar structural elements and arrangements. Which of the following hypotheses is most plausible in light of such structural similarities? a. Natural selection for cell motility repeatedly selected for microtubular arrays in circular patterns in the evolution of each of these structures. b. Motor proteins such as dynein must have evolved before any of these four kinds of structure. c. Cilia and flagella arise from centrioles. d. Loss of basal bodies should prevent cells from dividing in two. e. Cilia and flagella evolved separately in the same ancestral eukaryotic organism. c Which of the following is true of kinesin? a. Kinesin moves vesicles toward the minus end of microtubules. b. Kinesin is an intermediate filament protein. c. Kinesin hydrolyzes ATP. d. Kinesin moves vesicles toward the plus end of actin filaments. c Researchers tried to explain how vesicular transport occurs in cells by attempting to assemble the transport components. They set up microtubular tracks along which vesicles could be transported, and they added vesicles and ATP (because they knew the transport process requires energy). Yet, when they put everything together, there was no movement or transport of vesicles. What were they missing? a. an axon b. contractile microfilaments c. endoplasmic reticulum d. motor proteins d Cells require which of the following to form cilia or flagella? a. actin b. tubulin c. secretory vesicles d. laminin e. intermediate filaments b Spherocytosis is a human blood disorder associated with a defective cytoskeletal protein in the red blood cells (RBCs). What do you suspect is the consequence of such a defect? a. an insufficient supply of ATP in the RBCs b. abnormally shaped RBCs c. adherence of RBCs to blood vessel walls, causing plaque formation d. an insufficient supply of oxygentransporting proteins in the RBCs b The phase of the cell cycle associated with the doubling of the amount of DNA in the cell is... a. G0. b. G1. c. G2. d. M. e. S. e The longest phase of the cell cycle is... a. metaphase. b. prophase. c. telophase. d. interphase. e. anaphase. d Using polyethylene glycol (PEG), early G1 phase cells were fused with S phase cells. Of the following events, which would you expect to be induced in the G1 cells as a result of the fusion? a. cytokinesis b. condensation of chromosomes c. DNA replication d. mitosis e. spindle fiber formation c Which one of the following statements about the cell cycle is correct? a. Both G2 and Mphase are 4n in E. coli. b. Most cells in the human body are in G0. c. Cell growth occurs during G1 and G2, but not Sphase. d. G1 is easily distinguished from G2 in the microscope. e. DNA is replicated during Mphase. b Which one of the following statements about the cells in early human embryonic development is correct? a. They undergo a full cell cycle, but accelerate the rate at which they complete each phase. b. They bypass Sphase altogether. c. They undergo a full cell cycle, but the number of chromosomes is doubled following cytokinesis. d. They do not spend much (if any) time in G2. e. They are most accurately referred to as being in G0. d During which of the following phases of a human cell's cycle would it have a 4n amount of DNA? Choose all that apply. a. M b. G1 c. G0 d. S e. G2 a and e If we analyzed the DNA content of cultured human cells using fluorescence as described in class, and then measured DNA content again 24 hours after adding a drug that inhibited the cells from entering S phase (but did not otherwise affect the cell cycle), how would the graph of the amount of DNA per cell change from the initial data prior to administering the drug? a. The 2n peak would increase b. Both 2n peaks and 4n peaks would decrease c. The 4n peak would increase d. The 2n peak would decrease e. Both 2n and 4n peaks would increase a Which of the following does NOT occur during mitosis? a. separation of sister chromatids b. condensation of the chromosomes c. spindle formation d. separation of the spindle poles e. replication of the DNA e In human and many other eukaryotic species' cells, the nuclear membrane has to disappear to permit _____. a. the splitting of the centrosomes b. the disassembly of the nucleolus c. the attachment of microtubules to kinetochores d. cytokinesis c The drug cytochalasin B blocks the function of actin. Which of the following aspects of the cell cycle would be most disrupted by cytochalasin B? a. cleavage furrow formation and cytokinesis b. spindle formation c. spindle attachment to kinetochores d. cell elongation during anaphase e. DNA synthesis a Put these in order: Anaphase Metaphase Prophase Telophase Prometaphase Cytokinesis 1. Prophase 2. Prometaphase 3. Metaphase 4. Anaphase 5. Telophase 6. Cytokinesis What happens during: 1. Prophase 2. Prometaphase 3. Metaphase 4. Anaphase 5. Telophase 1. the microtubules of the spindle apparatus begin to assemble from individual tubulin subunits. As the identical chromatids of each pair of sister chromatids condense during this stage, they are held together by cohesin proteins. 2. is marked by fragmentation of the nuclear envelope, expansion of the spindle into the nuclear region, and attachment of some spindle fibers to the chromosomes via the kinetochores. 3. marked by the alignment of chromsomes along the metaphase plate, is brought about by kinetochores aligning and then remaining motionless relative to the poles of the cell. 4. the cohesin proteins are cleaved, and the kinetochores move toward the poles of the cell, separating the sister chromatids. 5. the kinetochore microtubules of the spindle disassemble. As the chromosomes reach the poles of the cell, the nuclear envelopes of the two new daughter nuclei form. 1. In prophase, the microtubules of the mitotic spindle _______. 2. In anaphase, the nonkinetochore microtubules _______ and mover past each other, and the kinetochore microtubules ____. 3. In telophase, the nonkinetochore microtubules ___________. 1. Lengthen 2. Lengthen; shorten 3. Disassemble Consider an animal cell in which motor proteins in the kinetochores normally pull the chromosomes along the kinetochore microtubules during mitosis. Suppose, however, that during metaphase, this cell was treated with an inhibitor that blocks the function of the motor proteins in the kinetochore, but allows the kinetochore to remain attached to the spindle. The inhibitor has no effect on any other mitotic process, including the function of the nonkinetochore microtubules. 1. Will this cell elongate during mitosis? 2. Will the chromosomes move to the poles of the cell? 3. Will the sister chromatids separate from each other? 1. Yes 2. No 3. Yes Of the three modes of gene regulation, which is the fastest in response time? a. Posttranslational control b. Transcriptional control c. Translational control d. All three are equally fast. a What is the role of lactose in regulating lac operon expression? a. It induces translation by binding to the repressor and removing it from the mRNA. b. It represses transcription by binding to the repressor. c. It induces transcription by binding directly to the promoter and attracting RNA Polymerase. d. It induces transcription by binding to the repressor and causing its release from the operator. d The lac repressor protein binds to the operator when it is ______. a. not bound to glucose b. bound to glucose c. not bound to lactose d. bound to lactose e. bound to arabinose c Of the three modes of gene regulation shown in Figure 18.1, which is the most efficient in resource use? a. Posttranslational control b. Transcriptional control c. Translational control. d. All three are equally efficient. b What's the function of... Lactose RNA Poymerase Is the regulatory gene part of the operon? Lactose: inactivates the repressor proteinso the lactoseutilization genes can be transcribed RNA Pol: transcribes the genes of the lac operon No Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If she moves the repressor gene (lacI), along with its promoter, to a position at some several thousand base pairs away from its normal position, we would expect the _____. a. repressor will no longer bind to the operator b. lac operon will function normally c. repressor will no longer be made d. lac operon will be expressed continuously e. repressor will no longer bind to the inducer b Which of the following characteristics, structures, or processes is common to bacteria and viruses? a. genetic material composed of nucleic acid b. cell division c. metabolism d. ribosomes e. independent existence a Viruses _____. a. use the host cell to copy themselves and then viruses synthesize their own proteins b. metabolize food and produce their own ATP c. use the host cell to copy themselves and make viral proteins d. manufacture their own ATP, proteins, and nucleic acids c Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If she moves the promoter for the lac operon to the region between the beta galactosidase (lacZ) gene and the permease (lacY) gene, which of the following would be likely? a. Beta galactosidase will not be produced. b. The three structural genes will be expressed normally. c. The cell will continue to metabolize but more slowly. d. RNA polymerase will no longer transcribe permease. e. The operon will still transcribe the lacZ and lacY genes, but the mRNA will not be translated. a Suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. If she moves the operator to the far end of the operon, past the transacetylase (lacA) gene, which of the following would likely occur when the cell is exposed to lactose? a. The inducer will no longer bind to the repressor. b. The repressor will no longer bind to the operator. c. The structural genes will be transcribed continuously. d. The operon will never be transcribed. e. The repressor protein will no longer be produced. c You are studying an operon that encodes a polycistronic mRNA for three structural genes of approximately equal size: gene A, gene B, and gene C. The mRNA is stable for about 2 minutes, and the genes are found in the order A, B, C from the 5' end to the 3' end. If you knew that the mRNA was degraded by a 3'→5' exonuclease, which of the following ratios of functional proteins (A:B:C) would you most likely observe? a. 5:10:10 b. 10:7:5 c. 5:7:10 d. 1:1:1 e. 3:5:8 b Which of the following statements about viruses is incorrect? a. Viruses contain nucleic acids. b. The most common type of genome found in a virus is a linear double stranded DNA. c. Influenza is an example of a virus that contains a segmented genome. d. Bacteriophage are viruses that infect bacteria. e. Since viruses can persist on their own, they can replicate independently outside of a host. e All viruses have a protein coat called a(n) ________, and some viruses have an additional "covering" called a(n) ________. a. envelope; capsid b. shell; cortex c. capsid; envelope d. inner membrane; outer membrane e. plasma membrane; cell wall c A viral particle which has been integrated into a bacterial genome is most accurately referred to as a: a. virioid. b. phage. c. provirus. d. plasmid. e. prophage. e HIV infects cells by recognizing the cellsurface markers of the target host cell with its own: a. RNA. b. glycoproteins. c. DNA. d. reverse transcriptase. e. capsid proteins. b Which one of the following statements about T4 is correct? a. The capsid, tail fiber protein, and base protein are examples of proteins expressed early in its replicative cycle. b. The genes expressed early in its replicative cycle are under the control of a weak promoter. c. It expresses nucleases during early gene expression to degrade the host genome, thus diverting resources to viral production. d. Upon attachment to a cell surface, the capsid injects a doublestranded RNA to the host cytosol. e. It is an example of a temperate phage, which lyses the host cells upon release of new viral particles. c Which one of the following describes an enzyme that a nonretroviral RNA virus would most likely have to provide on its own (or have produced from the viral genome)? a. Replicase b. Primase c. DNA polymerase d. RNA polymerase e. Helicase a Which one of the following most likely represents a way in which an animal virus would get into a cell that it infects? a. Injection of the DNA into the cell b. Fusion of an enveloped virus with a cell membrane c. Conjugation d. Transformation e. Fusion of a naked virus with the cell membrane b Which one of the following statements about HIV is incorrect? a. There is an RNA/DNA hybrid molecule at one point during viral genome replication. b. AIDS patients die of the HIV infection itself. c. HIV protease chops the HIV polyprotein into individual proteins since the host cannot process polycistronic messages. d. HIV integrate a form of its genome into the host's genome. e. HIV interacts with cellular CD4 receptors. b If the phrase "Madam, I'm Adam" were a DNA sequence, it would be an example of the type of DNA sequence ______. a. recognized by restriction enzymes b. recognized by reverse transcriptase c. that is most often cloned d. that is of no use in cloning a How do we describe transformation in bacteria? a. the creation of a strand of RNA from a DNA molecule b. the creation of a strand of DNA from an RNA molecule c. the infection of cells by a phage DNA molecule d. semiconservative replication of DNA e. assimilation of external DNA into a cell e Which answer best explains why restriction endonucleases like EcoRI create DNA fragments with sticky ends? a. They cut DNA at random locations to produce singlestranded tails that can hydrogenbond to one another. b. They make a staggered cut within the recognition site by cutting the two DNA strands at the same location. c. They make a staggered cut within the recognition site by cutting the two DNA strands at different locations. d. They cut both DNA strands within recognition sites that are palindromic sequences. c What is a plasmid? a. a circular DNA molecule that often replicates independently of the main chromosome(s) b. a type of virus that has a DNA genome and that infects certain types of human cells, including lung and respiratory tract tissue c. an organelle found in many bacteria and certain eukaryotes d. a type of virus that has an RNA genome, codes for reverse transcriptase, and inserts a cDNA copy of its genome into host cells a In genecloning projects, plasmids function to ______. a. create DNA copies of mRNA b. cut DNA into fragments c. create probes for library screening d. allow replication of the DNA that's being cloned d If one sample of DNA was cut with BamHI and another with BclI, and these two samples were mixed and treated with DNA ligase, what would occur? ^ ^ Bam: GGATCC Bc: TGATCA CCTAGG ACTAGT ^ ^ a. Both BamHIcut and BclIcut DNAs would be ligated, but only to DNA fragments cut with the same enzyme (for example, BamHI fragments would be ligated only to other BamHI fragments). b. No DNAs would be ligated (joined together). c. Only the BamHIcut DNA would be ligated. d. Only the BclIcut DNA would be ligated. e. Both BamHIcut and BclIcut DNAs would be ligated with no preference for which fragment is ligated to which other. e To isolate a cloned gene from a DNA library, researchers ______. a. probe the library using a labeled singlestranded DNA complementary to the gene b. sequence DNA from clones in the library to identify one with the desired gene c. probe the library using a labeled antibody specific for the gene d. isolate DNA from bacterial colonies and use reverse transcriptase to create cDNA from the desired gene a In recombinant DNA methods, the term vector can refer to _____. a. a SNP marker b. a DNA probe used to identify a particular gene c. a plasmid used to transfer DNA into a living cell d. the "sticky end" of a DNA fragment e. the enzyme (endonuclease) that cuts DNA into restriction fragments c Expression of a cloned eukaryotic gene in a bacterial cell involves many challenges. The use of mRNA and reverse transcriptase is part of a strategy to solve the problem of _____. a. posttranscriptional processing b. posttranslational processing c. nucleic acid hybridization d. electroporation e. restriction fragment ligation a Which of the following would NOT be true of cDNA produced using human brain tissue as the starting material? a. It could be used to create a complete genomic library. b. It could be amplified by the polymerase chain reaction. c. It lacks the introns of the human genes. d. It could be used as a probe to detect genes expressed in the brain. e. It was produced from mRNA using reverse transcriptase. a
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