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Interlude B
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Interlude E

Enzyme That Repairs DNA Is Blocked in Aging Cells

PNAS, 1 Sept. 2003

Researchers at the University of Texas Medical Branch at Galveston are contributing to that prospect with a new study exploring why the aging body is unable to defend against DNA damage in the power plants that fuel cells’ growth and activity, known as the mitochondria.

» Read the full article

Active Reading Questions

  1. DNA damage results from the almost constant barrage of a variety of environmental and internal agents that disrupt this complex molecule. One such damaging substance is free radical oxygen. For DNA to be repaired, which of the following must occur?
    a) Damaged DNA must be recognized.
    b) Damaged DNA must be removed.
    c) Damaged DNA must be replaced.
    d) All of the above.
  2. Repair proteins circulate in the cytoplasm of the cell. In order for them to be effective, they must enter either the nucleus or the mitochondria (both contain DNA subject to mutation). According to this article, which of the following happens as a result of aging?
    a) Repair proteins are found in much lower concentrations with age.
    b) Repair proteins fail to enter organelles to make repairs with age.
    c) Repair proteins cannot keep up with the amount of damage that occurs as aging occurs.
    d) Repair proteins are no longer synthesized as aging occurs.
  3. Explain what a mutation is in terms of what can happen to the DNA molecule itself. What types of events can result in mutations?
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