• Question: Why is DNA shaped x-shape why cant it be shaped differently?

    Asked by Zaina Babes to Barbara, Matt, Ravinder, Sophie, Tristan on 7 Mar 2015. This question was also asked by payney.
    • Photo: Barbara Shih

      Barbara Shih answered on 7 Mar 2015:

      Actually, DNA doesn’t have to be X-shaped! The x-shape is only a shape they temporarily take on at the point when they’re just about to divide. Here is an article on a different way of visualising chromosome structure : http://www.eurekalert.org/pub_releases/2013-09/babs-nt092413.php . In addition, some organisms can also have circular shaped DNA molecule (plasmid) that is separate from their chromosomes.

    • Photo: Ravinder Kanda

      Ravinder Kanda answered on 9 Mar 2015:

      The X shape of chromosome is often the way DNA is portrayed because it looks pretty. Sometimes the chromosomes are X shaped, but not always (have a look at http://en.wikipedia.org/wiki/Chromosome). The structure of DNA is a double helix; kinda like a twisted ladder, that is then wound up very tightly and squashed together to make the chromosomes

    • Photo: Matthew Moore

      Matthew Moore answered on 10 Mar 2015:

      It’s because it’s actually two chromosomes attached at the centre by a centromere, this is important in cell replication, so it looks like an X.

      It doesn’t need to be this shape, no. Chromatin rather than chromosomes is when DNA is not tightly packed into those characteristic X’s, in that form it is just long and stringy!

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