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Structure of DNA (Basics)

  1. May 16, 2015 #1
    I'm getting confused with the type of bonding (1) between the nucleotides and (2) between the nucleotide and the "sugar phosphate backbone".

    This diagram:

    http://tigger.uic.edu/classes/phys/phys461/phys450/ANJUM04/DNA_helix.jpg

    Shows hydrogen bonds between the nucleotide bases. But then Wiki

    Says they are joined by covalent bonds. Are they covalent hydrogen bonds?

    Really just need to know the type of bonding (1) between the nucleotides and (2) between the nucleotide and the "sugar phosphate backbone".

    If anyone can help please.
     
  2. jcsd
  3. May 16, 2015 #2
    Nucleotide: sugar & base & phosphate

    Nucleoside: sugar & base

    Nucleobase: base
     
  4. May 16, 2015 #3
    Ahh, think I see what you are saying, so the Nucleotide is the full thing and they are joined to each other via covalent bonds to make the backbone.

    However the two backbones (nucleotide chains) need joining together, through bonding of nucleobases and that bond is a Hydrogen bond.

    Does that sound right?

    Thanks for the reply!
     
  5. May 16, 2015 #4

    Ygggdrasil

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    Science Advisor

    Yes. DNA is a double helix consisting of two strands (sometimes we call one strand the Watson strand and the other the Crick strand). Each strand is a polymer of nucleotides connected via covalent bonds (phosphodiester bonds, to be precise). The Watson and Crick strands associate non-covalently through hydrogen bonding between the nucleobases.
     
  6. May 16, 2015 #5
    Yeah, they mean the joining of the nucleotides. They are covalently linked; sugar-phosphate backbone, phosophodiester, 3' and 5', that stuff.

    So in DNA, every unit/nucleotide is linked to three others. The one before and the one after in the polymer-backbone(covalently), and the one it pairs up with in the other strand(hydrogen bridge interaction).

    A picture that actually shows the phosphate part, the sugar part and the base part will make it clear, if it is not already.
     
    Last edited: May 16, 2015
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