Week Two Quiz

  1. You are studying bone remodeling and possible treatments for osteoporosis. Your project focuses on the expression of RANKL (RANK ligand). You start your studies by examine the expression of RANKL. Which cell would you choose?

    1. Osteoclasts
    2. Osteocytes
    3. Osteoblasts
    4. Pre-osteoclasts

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  2. You look up the size of the RANKL gene in an online database of the human genome and find it listed as ~ 45 kb. Your first experiment is to test the amount of RANKL mRNA expressed. You purify mRNA from the cytoplasm of cells and perform a Northern blot with a probe specific for RANKL mRNA and find a prominent band at ~ 2.2 kb. Which of the following best explains the difference in size between the gene and the mRNA?

    1. The gene contain introns
    2. There is a mistake in the online database
    3. The mRNA has degraded during the Northern blot procedure
    4. The gene contains a premature terminator of transcription

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  3. The RANKL protein contains 317 amino acids which would be encoded in 917 bases. Which of the following best explains why the RANKL mRNA is larger than the length required to encode the protein?

    1. The mRNA encodes more than one protein
    2. The mRNA contains a long string of adenosine at its 3' end
    3. The mRNA has received its 5' cap
    4. The mRNA contains introns

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  4. You find a cell line that expresses much less RANKL than other cells. Sequencing the genome in the cell line, you discover several mutations in a region a few kilobases upstream of the start codon for RANKL. This region is most likely which of the following?

    1. Intron
    2. Exon
    3. Promoter
    4. Enhancer

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  5. Your supervisor suggests adding parathyroid hormone to the cells. You would expect a Northern blot of the mRNA from the cells after adding of PTH to show which of the following?

    1. Longer RANKL mRNA
    2. Less RANKL mRNA
    3. Shorter RANKL mRNA
    4. More RANKL mRNA

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  6. If you analyzed the histones on the RANKL gene in those same cells after addition of PTH, you would expect to find which of the following?

    1. Acetylated histones
    2. Deacetylated histones
    3. More histones
    4. Fewer histones

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  7. The interior space of some bones contains bone marrow which is composed of developing red and white blood cells. Once developed, these cells must enter the circulatory system. Which type of endothelial cell lines the capillaries in bone marrow?

    1. Continuous
    2. Fenestrated
    3. Discontinuous

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  8. Neutrophils are immune cells that must cross the endothelium to fight bacterial infections in tissues. Integrins generate adhesion between neutrophils and endothelial cells. Besides adhesion, which other event likely results from the interaction of integrins on neutrophils and endothelial cells?

    1. Phosphorylation of cadherins
    2. Depolymerization of intermediate filaments
    3. Increase expression of VEGF receptor
    4. Increase expression of claudins

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  9. After the second game of the college football season, 60 members of the 97-member football team developed fever, malaise, loss of appetite and abdominal discomfort. Within a few days 30 players became jaundiced. Blood samples were drawn from all members of the team to test for antibodies to Hepatitis A (the presumed diagnosis) and for elevated liver enzymes.

    Lab testing revealed that 91 had elevated liver enzymes of which 90 had IgM antibody indicative of acute Hepatitis A infection. Two players with normal enzymes had IgG antibody, indicating that they had previously been exposed to Hepatitis A and were now immune.

    What is the cumulative incidence of Hepatitis A on the football team?

    1. 90/97
    2. 90/91
    3. 91/95
    4. 91/97
    5. 90/95

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