Cell Biology/Cell Exam Biochemistry: Final Exam Latest Update 2023, Exams of Biochemistry

Download Cell Biology/Cell Exam Biochemistry: Final Exam Latest Update 2023 and more Exams Biochemistry in PDF only on Docsity! Cell Biology/Cell Exam Biochemistry: Final Exam Latest Update 2023 1) Which of the following choices best describes the role of the lysosome? (a) transport of material to the Golgi (b) clean-up, recycling, and disposal of macromolecules (c) sorting of transport vesicles (d) the storage of excess macromolecules 2) are fairly small organelles that provide a safe place within the cell to carry out certain biochemical reactions that generate harmful, highly reactive oxygen species. These chemicals are both generated and broken down in the same location. (a) Nucleosomes (b) Lysosomes (c) Peroxisomes (d) Endosomes 3) Which of the following monomer building blocks is necessary to assemble selectively permeable boundaries around and inside cells? (a) sugars (b) fatty acids (c) amino acids (d) nucleotides 4) DNA and RNA are different types of nucleic acid polymer. Which of the following is true of DNA but not true of RNA? (a) It contains uracil. (b) It contains thymine. (c) It is single-stranded. (d) It has 5′-to-3′ directionality. 5) Because there are four different monomer building blocks that can be used to assemble RNA polymers, the number of possible sequence combinations that can be created for an RNA molecule made of 100 nucleotides is . (a) 1004 (b) 4100 (c) 4 × 100 BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update 2022 (d) 100/4 BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update 2022 (c) G-C (d) C-G BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update 2022 16) Energy required by the cell is generated in the form of ATP. ATP is hydrolyzed to power many of the cellular processes, increasing the pool of ADP. As the relative amount of ADP molecules increases, they can bind to glycolytic enzymes, which will lead to the production of more ATP. The best way to describe this mechanism of regulation is . (a) feedback inhibition. (b) oxidative phosphorylation. (c) allosteric activation. (d) substrate-level phosphorylation. 17) Fred Griffith studied two strains of Streptococcus pneumonia, one that causes a lethal infection when injected into mice, and a second that is harmless. He observed that pathogenic bacteria that have been killed by heating can no longer cause an infection. But when these heat-‐killed bacteria are mixed with live, harmless bacteria, this mixture is capable of infecting and killing a mouse. What did Griffith conclude from this experiment? (a) The infectious strain cannot killed by heating. (b) The heat-killed pathogenic bacteria “transformed” the harmless strain into a lethal one. (c) The harmless strain somehow revived the heat-killed pathogenic bacteria. (d) The mice had lost their immunity to infection with S. pneumoniae. 18) The human genome is a diploid genome. However, when germ-‐line cells produce gametes, these specialized cells are haploid. What is the total number of chromosomes found in each of the gametes (egg or sperm) in your body? (a) 22 (b) 23 (c) 44 (d) 46 19) Which of the following questions would not be answered by using karyotyping? (a) Is the individual genetically female or male? (b) Do any of the chromosomes contain pieces that belong to other chromosomes? (c) Does the individual have an extra chromosome? (d) Do any chromosomes contain point mutations? 20) Although the chromatin structure of interphase and mitotic chromosomes is very compact, DNA-‐binding proteins and protein complexes must be able to gain access to the DNA molecule. Chromatin-‐remodeling complexes provide this access by . (a) recruiting other enzymes. (b) modifying the N-terminal tails of core histones. (c) using the energy of ATP hydrolysis to move nucleosomes. (d) denaturing the DNA by interfering with hydrogen-bonding between base pairs. BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update 2022 21) The N-‐terminal tail of histone H3 can be extensively modified, and depending on the number, location, and combination of these modifications, these changes may promote the formation of heterochromatin. What is the result of heterochromatin formation? (a) increase in gene expression (b) gene silencing (c) recruitment of remodeling complexes (d) displacement of histone H1 22) You prepare bacterial cell extracts by lysing the cells and removing insoluble debris via centrifugation. These extracts provide the proteins required for DNA replication. Your DNA template is a small, double-‐stranded circular piece of DNA (a plasmid) with a single origin of replication and a single replication termination site. The termination site is on the opposite side of the plasmid from the origin. Which of the following statements is true with respect to this in vitro replication system? (a) There will be only one leading strand and one lagging strand produced using this template. (b) The leading and lagging strands compose one half of each newly synthesized DNA strand. (c) The DNA replication machinery can assemble at multiple places on this plasmid. (d) One daughter DNA molecule will be slightly shorter than the other. 23) You have discovered an “Exo–” mutant form of DNA polymerase in which the 3′-‐to-‐5′ exonuclease function has been destroyed but the ability to join nucleotides together is unchanged. Which of the following properties do you expect the mutant polymerase to have? (a) It will polymerize in both the 5′-to-3′ direction and the 3′-to-5′ direction. (b) It will polymerize more slowly than the normal Exo+ polymerase. (c) It will fall off the template more frequently than the normal Exo+ polymerase. (d) It will be more likely to generate mismatched base pairs. BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update 2022 (d) Exons 2 and 3 must have different numbers of nucleotides. BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update 2022 30) Which of the following molecules is thought to have arisen first during evolution? (a) protein (b) DNA (c) RNA (d) all came to be at the same time 31) Investigators performed nuclear transplant experiments to determine whether DNA is altered irreversibly during development. Which of the following statements about these experiments is true? (a) Because the donor nucleus is taken from an adult animal, the chromosomes from the nucleus must undergo recombination with the DNA in the egg for successful development to occur. (b) The embryo that develops from the nuclear transplant experiment is genetically identical to the donor of the nucleus. (c) The meiotic spindle of the egg must interact with the chromosomes of the injected nuclei for successful nuclear transplantation to occur. (d) Although nuclear transplantation has been successful in producing embryos in some mammals with the use of foster mothers, evidence of DNA alterations during differentiation has not been obtained for plants. 32) Which of the following statements about transcriptional regulators is false? (a) Transcriptional regulators usually interact with the sugar–phosphate backbone on the outside of the double helix to determine where to bind on the DNA helix. (b) Transcriptional regulators will form hydrogen bonds, ionic bonds, and hydrophobic interactions with DNA. (c) The DNA-binding motifs of transcriptional regulators usually bind in the major groove of the DNA helix. (d) The binding of transcriptional regulators generally does not disrupt the hydrogen bonds that hold the double helix together. BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update 2022 Note: Questions 33 to 34 use the following information and the data in the figure below. You are interested in understanding the gene regulation of Lkp1, a protein that is normally produced in liver and kidney cells in mice. Interestingly, you find that the LKP1 gene is not expressed in heart cells. You isolate the DNA upstream of the LKP1 gene, place it upstream of the gene for green fluorescent protein (GFP), and insert this entire piece of recombinant DNA into mice. You find GFP expressed in liver and kidney cells but not in heart cells, an expression pattern similar to the normal expression of the LKP1 gene. Further experiments demonstrate that there are three regions in the promoter, labeled A, B, and C in the figure below, that contribute to this expression pattern. Assume that a single and unique transcription factor binds each site such that protein X binds site A, protein Y binds site B, and protein Z binds site C. You want to determine which region is responsible for tissue-‐specific expression, and create mutations in the promoter to determine the function of each of these regions. In the figure below, if the site is missing, it is mutated such that it cannot bind its corresponding transcription factor. 33) Which of the following proteins is likely to act as a gene repressor? (a) factor X (b) factor Y (c) factor Z (d) none of the above 34) Which of the following proteins are likely to act as gene activators? (a) factors X and Y (b) factors X and Z (c) factors Y and Z (d) factor X only 35) miRNAs, tRNAs, and rRNAs all . (a) do not code for proteins. (b) act in the nucleus. BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update 2022 (b) DNA is negatively charged. (c) heat disrupts hydrogen-bonding between complementary nucleotides. (d) DNA is positively charged. BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update 2022 41) Your friend works at the Centers for Disease Control and Prevention and has discovered a brand-‐new virus that has recently been introduced into the human population. She has just developed a new assay that allows her to detect the virus by using PCR products made from the blood of infected patients. The assay uses primers in the PCR assay that hybridize to sequences in the viral genome. Your friend is distraught because of the result she obtained (see Figure below) when she looked at PCR products made using the blood of three patients suffering from the viral disease, using her own blood, and using a leaf from her petunia plant. You advise your friend not to panic, as you believe she is missing an important control. Which one of the choices listed below is the best control for clarifying the results of her assay? Explain your answer. (a) a PCR assay using blood from a patient who is newly infected but does not yet show symptoms (b) a PCR assay using blood from a dog (c) a PCR assay using blood from an uninfected person (d) repeating the experiments she has already done with a new tube of polymerase 42) Why are dideoxyribonucleoside triphosphates used during DNA sequencing? (a) They cannot be incorporated into DNA by DNA polymerase. (b) They are incorporated into DNA particularly well by DNA polymerases from thermophilic bacteria. (c) Incorporation of a dideoxyribonucleoside triphosphate leads to the termination of replication for that strand. (d) Dideoxyribonucleoside triphosphates are more stable than deoxyribonucleoside triphosphates. 43) Which type of lipids are the most abundant in the plasma membrane? (a) phospholipids (b) glycolipids (c) sterols (d) triacylglycerides BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update 2022 44) Where does most new membrane synthesis take place in a eukaryotic cell? (a) at the Golgi apparatus (b) at the endoplasmic reticulum (c) at the plasma membrane (d) in the mitochondria (e) on ribosomes 45) Consider the apical location of a particular protein expressed in gut epithelial cells, illustrated in the figure below. Which type of defect described below is the most likely to cause the redistribution of that protein around the entire cell, shown in the figure below? (a) a nonfunctional protein glycosylase (b) the deletion of a junctional protein (c) the truncation of a protein found in the extracellular matrix (d) a nonfunctional flippase 46. Which of the following statements about tumor suppressor genes is false? (a) Gene amplification of a tumor suppressor gene is less dangerous than gene amplification of a proto-oncogene. (b) Cells with one functional copy of a tumor suppressor gene will usually proliferate faster than normal cells. (c) Inactivation of tumor suppressor genes leads to enhanced cell survival and proliferation. (d) Individuals with only one functional copy of a tumor suppressor gene are more prone to cancer than individuals with two functional copies of a tumor suppressor gene. 47. A metastasis is . (a) a secondary tumor in a different part of the body that arises from a cell from the primary tumor. (b) a cell that is dividing in defiance of normal constraints. (c) a part of the primary tumor that has invaded the surrounding tissue. (d) the portion of the cancerous tumor that displays genetic instability. 48. The artificial introduction of three key into an adult cell can convert the adult cell into a cell with the properties of ES cells. (a) chromosomes BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update 2022 55. In step 4 of glycolysis, a six-carbon sugar (fructose 1,6-bisphosphate) is cleaved to produce two three-carbon molecules (dihydroxyacetone phosphate and glyceraldehyde 3-phosphate). Which enzyme catalyzes this reaction? (a) aldolase (b) phosphoglucose isomerase (c) enolase (d) triose phosphate isomerase 56. Pyruvate can be converted into many other molecules by various biosynthetic and metabolic pathways, which makes it a central hub in the regulation of cellular metabolism. Which of the following molecules is not made from pyruvate? (a) oxaloacetate (b) ethanol (c) lactate (d) NADH 57. Because bacteria do not have mitochondria, they cannot produce ATP in a membrane-dependent fashion. A. True B. False 58. After isolating the rough endoplasmic reticulum from the rest of the cytoplasm, you purify the RNAs attached to it. Which of the following proteins do you expect the RNA from the rough endoplasmic reticulum to encode? (a) soluble secreted proteins (b) ER membrane proteins (c) plasma membrane proteins (d) all of the above BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update 2022 59. Cells have oligosaccharides displayed on their cell surface that are important for cell–cell recognition. Your friend discovered a transmembrane glycoprotein, GP1, on a pathogenic yeast cell that is recognized by human immune cells. He decides to purify large amounts of GP1 by expressing it in bacteria. To his purified protein he then adds a branched 14-sugar oligosaccharide to the asparagine of the only Asn-X-Ser sequence found on GP1 (Figure Q15-48). Unfortunately, immune cells do not seem to recognize this synthesized glycoprotein. Which of the following statements is a likely explanation for this problem? Figure Q15-48 (a) The oligosaccharide should have been added to the serine instead of the asparagine. (b) The oligosaccharide should have been added one sugar at a time. (c) The oligosaccharide needs to be further modified before it is mature. (d) The oligosaccharide needs a disulfide bond. 60. Which of the following statements about secretion is true? (a) The membrane of a secretory vesicle will fuse with the plasma membrane when it discharges its contents to the cell’s exterior. (b) Vesicles for regulated exocytosis will not bud off the trans Golgi network until the appropriate signal has been received by the cell. (c) The signal sequences of proteins destined for constitutive exocytosis ensure their packaging into the correct vesicles. BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update 2022 (d) Proteins destined for constitutive exocytosis aggregate as a result of the acidic pH of the trans Golgi network BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update 2022 68. Which of the following statements about G-protein-coupled receptors (GPCRs) is false? (a) GPCRs are the largest family of cell-surface receptors in humans. (b) GPCRs are used in endocrine, paracrine, and neuronal signaling. (c) GPCRs are found in yeast, mice, and humans. (d) The different classes of GPCR ligands (proteins, amino acid derivatives, or fatty acids) bind to receptors with different numbers of transmembrane domains. 69. At desmosomes, cadherin molecules are connected to . (a) actin filaments. (b) intermediate filaments. (c) microtubules. (d) gap junctions. 70. The growth factor RGF stimulates proliferation of cultured rat cells. The receptor that binds RGF is a receptor tyrosine kinase called RGFR. Which of the following types of alteration would be most likely to prevent receptor dimerization? (a) a mutation that increases the affinity of RGFR for RGF (b) a mutation that prevents RGFR from binding to RGF (c) changing the tyrosines that are normally phosphorylated on RGFR dimerization to alanines (d) changing the tyrosines that are normally phosphorylated on RGFR dimerization to glutamic acid 71. Covalent bonds between protein monomers hold together cytoskeletal (all three) filaments. A. True B. False 72. Cadherins . (a) are used to transfer proteins from one cell to another. (b) mediate cell–cell attachments through homophilic interactions. (c) are abundant in the plant cell wall. (d) bind to collagen fibrils. BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update 2022 73. Which of the following statements about gap junctions is false? (a) Gap junctions are made of connexons. (b) Molecules up to 1000 daltons in molecular mass can move across gap junctions. (c) Because gap junctions do not allow ions to pass through, they are not used for electrically coupling cells. (d) Gap junctions can close in response to extracellular signals. 74. is directly involved in muscle contraction A. actin B. intermediate filaments C. microtubules 75. You are interested in understanding the regulation of nuclear lamina assembly. To create an in vitro system for studying this process you start with partly purified nuclear lamina subunits to which you will add back purified cellular components to drive nuclear lamina assembly. Before you start doing experiments, your instructor suggests that you consider what type of conditions would be most amenable to the assembly of the nuclear lamina from its individual subunits in vitro. Which of the following conditions do you predict would be most likely to enhance the assembly of the nuclear lamina? (a) addition of phosphatase inhibitors (b) addition of ATP (c) addition of a concentrated salt solution that is 10 times the concentration normally found in the nucleoplasm (d) addition of protein kinase inhibitors 76. Which of the situations below will enhance microtubule shrinkage? (a) addition of a drug that inhibits GTP exchange on free tubulin dimers (b) addition of a drug that inhibits hydrolysis of the GTP carried by tubulin dimers (c) addition of a drug that increases the affinity of tubulin molecules carrying GDP for other tubulin molecules (d) addition of a drug that blocks the ability of a tubulin dimer to bind to γ-tubulin BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update 2022 77. Which of the following statements is correct? Kinesins and dyneins . (a) have tails that bind to the filaments. (b) move along both microtubules and actin filaments. (c) often move in opposite directions to each other. (d) derive their energy from GTP hydrolysis. 78. Which of the following statements is true? (a) The mitotic spindle is largely made of intermediate filaments. (b) The contractile ring is made largely of microtubules and actin filaments. (c) The contractile ring divides the nucleus in two. (d) The mitotic spindle helps segregate the chromosomes to the two daughter cells. 79. Before chromosomes segregate in M phase, they and the segregation machinery must be appropriately prepared. Indicate whether the following statement is true or false. Sister chromatids are held together by condensins from the time they arise by DNA replication until the time they separate at anaphase. A. True B. False 80. Each centrosome contains a pair of centrioles and hundreds of γ-tubulin rings that nucleate the growth of microtubules. A. True B. False 81. Which of the following statements is true? A. (a) Anaphase A must be completed before anaphase B can take place. B. (b) In cells in which anaphase B predominates, the spindle will elongate much less than in cells in which anaphase A dominates. C. (c) In anaphase A, both kinetochore and interpolar microtubules shorten. D. (d) In anaphase B, microtubules associated with the cell cortex shorten. BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update 2022 B. C. D. BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update 2022 89. Proteoglycans in the extracellular matrix of animal tissues . (a) chiefly provide tensile strength. (b) allow cartilage to resist compression. (c) are linked to microtubules through the plasma membrane. (d) are polysaccharides composed of glucose subunits. 90. Match the labeled parts of Figure Q20-20 with the phrase that best matches the part. Each part will only be used once. Figure Q20-20 connective tissue A. B. C. D. BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update 2022