Chapter 6

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Chapter 6
2012-02-09 22:32:56
Mota Bio

Test Questions
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  1. When biologists wish to
    study the internal ultrastructure of cells, they can achieve the finest
    resolution by using
    a transmission electronic microscope.
  2. The advantage of light
    microscopy over electron microscopy is that
    light microscopy allows one to view dynamic processes in living cells.
  3. A primary objective of cell fractionation is to
    separate the major organelles so that their particular functions can be determined.
  4. In the fractionation of homogenized cells using centrifugation, the primary factor that determines
    whether a specific cellular component ends up in the supernatant or the pellet
    the size and weight of the component.
  5. Which of the following correctly lists the order in which cellular components will be found in the
    pellet when homogenized cells are treated with increasingly rapid spins in a
    • nucleus
    • mitochondria
    • ribosomes
  6. Green fluorescent protein (GFP) can be used to fluorescently label a specific protein in cells by
    genetically engineering cells to synthesize the target protein fused to GFP.
    What is the advantage of using GFP fusions to visualize specific proteins,
    instead of staining cells with fluorescently labeled probes that bind to the
    target protein?
    • GFP fusions enable one to track changes in the location of the protein in living cells; staining usually
    • requires preserved cells.
  7. What is the reason that a modern electron microscope (TEM) can resolve biological images to the subnanometer
    level, as opposed to tens of nanometers achievable for the best
    super-resolution light microscope?
    Electron beams have much shorter wavelengths than visible light.
  8. What technique would be most appropriate to use to observe the movements of condensed chromosomes during cell division?
    light microscopy
  9. What are not parts of a prokaryotic cells?
    an endoplasmic reticulum
  10. The volume enclosed by the plasma membrane of plant cells is often much larger than the corresponding volume in animal cells. The most reasonable explanation for this observation is
    plant cells contain a large vacuole that reduces the volume of the cytoplasm.
  11. A mycoplasma is an organism with a diameter between 0.1 and 1.0 µm. What does the organism's size tell you about how it might be classified?
    It could be a very small bacterium.
  12. What is a major cause of the size limits for certain types of cells?
    the need for a surface area of sufficient area to support the cell's metabolic needs
  13. Bacteria and Archaea cells differ how?
    Archaea cells contain small membrane-enclosed organelles; bacteria do not
  14. The evolution of eukaryotic cells most likely involved
    endosymbiosis of an aerobic bacterium in a larger host cell–the endosymbiont evolved into mitochondria.
  15. Prokaryotes are classified as belonging to two different domains. What are the domains?
    Bacteria and Archaea
  16. If radioactive deoxythymidine triphosphate (dTTP) is added to a culture of rapidly growing
    bacterial cells, where in the cell would you expect to find the greatest concentration of radioactivity?
  17. Centrosomes are absent in?
    plant cells
  18. Large numbers of ribosomes are present in cells that specialize in producing which of the following
  19. The nuclear lamina is an array of filaments on the inner side of the nuclear membrane. If a method were found that could cause the lamina to fall into disarray, what would you expect
    to be the most likely consequence?
    a change in the shape of the nucleus
  20. Recent evidence shows that when chromosomes decondense during interphase, their DNA molecules do not intermingle. Instead, they occupy distinct territories within the nucleus.
    Considering the structure and location of the following structures, which is most likely to be involved in chromosome location?
    the nuclear matrix
  21. A cell with a predominance of free ribosomes is most likely
    producing primarily cytoplasmic proteins
  22. Which type of organelle or structure is primarily involved in the synthesis of oils, phospholipids, and
    smooth endoplasmic reticulum
  23. Which structure is the site of the synthesis of proteins that may be exported from the cell?
    rough ER
  24. The Golgi apparatus has a polarity or sidedness to its structure and function. Describe its polarity.
    Proteins, soluble proteins, lipids may be sorted and modified as they move from one side of the Golgi to the other.

    Transport vesicles fuse with one side of the Golgi and leave from the opposite side.
  25. The fact that the outer membrane of the nuclear envelope has bound ribosomes allows one to most
    reliably conclude that
    at least some of the proteins that function in the nuclear envelope are made by the ribosomes on the nuclear envelope.
  26. The difference in lipid and protein composition between the membranes of the endomembrane system is largely determined by
    the function of the Golgi apparatus in sorting and directing membrane components
  27. Hydrolytic enzymes must be segregated and packaged to prevent general destruction of cellular components. Which of the following organelles contains these hydrolytic enzymes in animal cells?
  28. Proteins that are secreted by prokaryotes are synthesized on...?
    ribosomes that are bound to the cytoplasmic surface of the plasma membrane
  29. Tay-Sachs disease is a human genetic abnormality that results in cells accumulating and becoming
    clogged with very large and complex lipids. Which cellular organelle must be involved in this condition?
    the lysosome
  30. The liver is involved in detoxification of many poisons and drugs. Which of the following structures is
    primarily involved in this process and therefore abundant in liver cells?
    smooth ER
  31. What produces and modifies polysaccharides that will be secreted?
    Golgi apparatus
  32. What organelle contains hydrolytic enzymes?
  33. Which organelle often takes up much of the volume of a plant cell?
  34. Which organelle is the
    primary site of ATP synthesis in eukaryotic cells?
  35. Which plant cell organelle contains its own DNA and ribosomes?
  36. Which animal cell organelle contains enzymes that transfer hydrogen from various substrates to oxygen?
  37. Thylakoids, DNA, and ribosomes are all components found in
  38. In a plant cell, DNA may be found
    in the nucleus, mitochondria, and chloroplasts
  39. The chemical reactions involved in respiration are virtually identical between prokaryotic and
    eukaryotic cells. In eukaryotic cells, ATP is synthesized primarily on the inner membrane of the mitochondria. In light of the endosymbiont theory for the evolutionary origin of mitochondria, where is most ATP synthesis likely to occur in prokaryotic cells?
    on the plasma membrane
  40. One of the key innovationsin the evolution of eukaryotes from a prokaryotic ancestor is the endomembrane system. What eukaryotic organelles or features might have evolved as a part of, or as an elaboration of, the endomembrane system?
    nuclear envelope
  41. A cell has the following molecules and structures: enzymes, DNA, ribosomes, plasma membrane, and
    mitochondria. It could be a cell from
    nearly any eukaryotic organism
  42. Which type of organelle is found in plant cells but not in animal cells - Ribosomes, Mitochondria, nuclei, or plastids?
  43. Why isn't the mitochondrion classified as part of the endomembrane system?
    Its structure is not derived from the ER or Golgi
  44. In a liver cell detoxifying alcohol and some other poisons, the enzymes of the peroxisome remove hydrogen from these molecules and
    transfer the hydrogen to oxygen molecules to generate hydrogen peroxide
  45. How does the cell multiply its peroxisomes?
    They split in two after they become sufficiently large
  46. Motor proteins provide formolecular motion in cells by interacting with what types of cellular
    cytoskeletal structures
  47. Movement of vesicles within the cell depends on what cellular structures?
    microtubules and motor proteins
  48. The smallest cell structure that would most likely be visible with a standard (not super-resolution) research-grade light microscope is
    a mitochondrion
  49. Which of the following contain the 9 + 2 arrangement of microtubules, consisting of nine doublets of
    microtubules surrounding a pair of single microtubules?
    both flagella and motile cilia
  50. Vinblastine, a drug that inhibits microtubule polymerization, is used to treat some forms of cancer.
    Cancer cells given vinblastine would be unable to
    separate chromosomes during cell division.

  51. The differences among the three categories of cytoskeletal elements outlined in the table above would suggest that each of the following has specialized roles. This suggests?
    microtubules and chromosome movement
  52. Centrioles, cilia, flagella, and basal bodies have remarkably similar structural elements and
    arrangements. What arises from the centrioles?
    Cilia and flagella
  53. If an individual has abnormal microtubules, due to a hereditary condition, in which organs or tissues would you expect dysfunction?
    • sperm, larynx, and trachea
    • cells and tissues that contain flagella or cilia
  54. Cytochalasin D is a drug that prevents actin polymerization. A cell treated with cytochalasin D will still be able to
    move vesicles around the cell.
  55. In the cytoskeleton, movement of cilia and flagella is the result of
    motor proteins causing microtubules to move relative to each other
  56. Cells require which organelle to form cilia or flagella?
  57. Microtubules, microfilaments, plant cell walls, intermediate filaments, and nuclear lamina all determine and maintain the structure of a plant cell. Which is distinct from the others in composition?
    Plant cell walls
  58. What do the cell walls of plants and the extracellular matrix of animal cells have in common?
    They have functional connections with the cytoskeleton inside the cell.
  59. The cell walls of bacteria, fungi, and plant cells and the extracellular matrix of animal cells are all external to the plasma membrane. What characteristic is common in all of them?
    They are constructed of polymers that are synthesized in the cytoplasm and then transported out of the cell.
  60. When a potassium ion (K+) moves from the soil into the vacuole of a cell on the surface of a root, it must pass through several cellular structures.
    Describe the order in which these structures will be encountered by the ion
    • primary cell wall → plasma
    • membrane → cytoplasm → vacuole
  61. A mutation that disrupts the ability of an animal cell to add polysaccharide modifications to proteins would most likely cause defects in its
    Golgi apparatus and extracellular matrix.
  62. The extracellular matrix is thought to participate in the regulation of animal cell behavior by communicating information from the outside to the inside of the cell via...?
  63. Plasmodesmata in plant cells are most similar in function to which structures in animal cells?
    gap junctions
  64. Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through
    gap junctions.
  65. Which of the following makes it necessary for animal cells, although they have no cell walls, to have intercellular junctions?
    Maintenance of tissue integrity and barriers to fluid leakage requires cells to adhere tightly to one another.
  66. Recent evidence shows that signals from the extracellular matrix (ECM) can regulate the expression of genes in the cell nucleus. A likely mechanism is that
    mechanical signals of the ECM can alter the cytoskeleton, which can alter intracellular signaling
  67. Signals between the ECM and the cytoskeleton may be transmitted by
  68. ECM proteins are made by ribosomes in which part of a eukaryotic cell?
    rough ER
  69. What types of proteins are not synthesized in the rough ER?
    mitochondrial proteins

  70. Which of the trees in this figure groups the domains according to similarities in cellular size and architecture?
    Bacteria Archae Eukarya
  71. A biologist wants specifically to examine the surfaces of different types of cells in kidney
    tubules of small mammals. The cells in question can be distinguished by:
    -external shape
    -3-D characteristics.
    What is the best method to go about her study?
    scanning electron microscopy
  72. A newspaper ad for a local toy store indicates that a very inexpensive microscope available for a small
    child is able to magnify specimens nearly as much as the much more costly microscope available in your college lab. What is the primary reason for the price difference?
    The toy microscope magnifies a good deal, but has low resolution and therefore poor quality images
  73. A biologist ground up some plant leaf cells and then centrifuged the mixture to fractionate the
    organelles. Organelles in one of the heavier fractions could produce ATP in the light, whereas organelles in the lighter fraction could produce ATP in the dark. The heavier and lighter fractions are most likely to contain, respectively
    chloroplasts and mitochondria.
  74. -nuclear envelope
    -Golgi apparatus
    -plasma membrane

    Which structure is not part of the endomembrane
  75. -chloroplast
    -wall made of cellulose
    -central vacuole

    Which is in both plant and animal cells?
  76. Which of the following is present in a prokaryotic cell?
    -nuclear envelope
  77. Cyanide binds with at least one molecule involved in producing ATP. If a cell is exposed to cyanide, most
    of the cyanide will be found within the
  78. What is the most likely pathway taken by a newly synthesized protein that will be secreted by a cell?
    ER →Golgi →vesicles that fuse with plasma membrane
  79. Which cell would be best for studying lyosomes?
    phagocytic white blood cell
  80. Name the function of each structure:
    • nucleolus; production of ribosomal subunits
    • lysosome; intracellular digestion
    • ribosome; protein synthesis
    • Golgi; protein trafficking
    • Microtubules; organelle movement