DNA replication

xantox, 3 July 2007 in Gallery

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Using computer animation1 based on molecular research2 it is possible to see how DNA is actually copied in living cells. This animation shows the “assembly line” of biochemical machines which pull apart the DNA double helix and output a copy of each strand. The DNA to be copied enters the whirling blue molecular machine, called helicase, which spins it as fast as a jet engine as it unwinds the double helix into two strands. One strand is copied continuously, and can be seen spooling off on the other side. Things are not so simple for the other strand, because it must be copied backwards, so it is drawn out repeatedly in loops and copied one section at a time. The end result is two new DNA molecules.

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  1. Drew Berry, “DNA animation”, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia (courtesy of the author). © 2007 Howard Hughes Medical Institute []
  2. T. A. Baker, S. P. Bell, “Polymerases and the Replisome: Machines within Machines“, Cell, 92:295-305 (1998); K. P. Lemon, A. D. Grossman, “Movement of Replicating DNA through a Stationary Replisome“, Molecular Cell, 6, 6:1321-1330 (2000); M. R. Singleton, M. R. Sawaua, T. Ellenberger, D. B. Wigley, “Crystal structure of T7 gene 4 ring helicase indicates a mechanism for sequential hydrolysis of nucleotides“, Cell 101:589-600 (2000); D. S. Johnson, L. Bai, B. Y. Smith, S. S. Patel, M. D. Wang, “Single-Molecule Studies Reveal Dynamics of DNA Unwinding by the Ring-Shaped T7 Helicase“, Cell 129, 7:1299-1309 (2007). []

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6 Comments to “DNA replication”

View Comments in: Français (11) Italiano (10)

  1. 1

    absolutely incredible!

  2. 2
    Jim Clarage (uh.edu)

    Please post more on your blog. It is a terrific resource for physicists.

  3. 3

    That is really, really amazing!

  4. 4
    Sébastien Bourdeau

    Spectacular! But i would have a request, would it be possible to identify other than the helicase, the other ‘machines’ that are in this process of coping the stran of DNA?

  5. 5

    The animation clearly shows the violet DNA Polymerase (the copier) and the green sliding clamp protein (which keeps the DNA Polymerase into place). The actual machinery is more complicated, I suggest to read the literature in footnote #2 for more details about the replication fork.

  6. 6
    Sébastien Bourdeau

    Thanks a lot, I appreciate it. Only in grade 12 biology, but can still understand the basics. Thanks a lot.

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