This video entertainingly supplements this 3d animation of DNA strand replication. Does this process happen serially from the beginning to the end of a DNA strand (like having to unzip a six foot long zipper - example A below) or does the strand get chopped up into chunks, unzipped individually, replicated then brought back together (example B)?

enter image description here

I suspect the answer is case A. If so, is any phase of replication done in a parallel fashion? I would think something has to be (since it happens so fast and serial anything is typically very slow in comparison).

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    $\begingroup$ The DNA isn't cleaved, but replication can be initiated at multiple points on a chromosome and proceed in both directions. I'll elaborate on this later and post an answer in the future if no one else has. This paper estimates that there are 10,000 to 100,000 replication origins in a human cell. This means that the average leading strand would be approximately 60,000 to 600,000 bp long. $\endgroup$
    – canadianer
    Commented Apr 21, 2017 at 22:40
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    $\begingroup$ It's like having a zipper with multiple "pulls" along its length. $\endgroup$
    – canadianer
    Commented Apr 21, 2017 at 22:52
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    $\begingroup$ My personal opinion is that videos of this type and 3D animations are scientific poison. OK, for popularising science, but not a useful source of serious information. Rather than speculation, however intelligent, I suggest you consult text books that have been carefully written by experts, professionally illustrated, and edited by other experts. You can get access to older editions of some of these on NCBI Bookshelf: ncbi.nlm.nih.gov/books. If you search there for DNA replication you will find clear and comprehensive accounts to answer your question. $\endgroup$
    – David
    Commented Apr 21, 2017 at 22:54
  • $\begingroup$ @canadianer, you're picture is perfect! That's the answer! $\endgroup$
    – zelusp
    Commented Apr 21, 2017 at 23:46
  • $\begingroup$ @David, thank you for the link. I'd like to add that popularizing science is good for science (which is antithetical to poison). Science without much interest or support doesn't get very far $\endgroup$
    – zelusp
    Commented Apr 21, 2017 at 23:54


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