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Why can't adenine and cytosine pairs form?

  1. Apr 10, 2005 #1
    hi I was curious Why can't adenine and cytosine pairs form? Like I know it doesn't happen but WHY?

    thanks for your help guys and girls!
     
  2. jcsd
  3. Apr 10, 2005 #2

    Andrew Mason

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    It is not that they can't bond at all. It is just that the total bond strength is not very strong, so it is not stable. All bonds are hydrogen bonds, so to make a strong molecular bond there have to be many points of contact between points with opposite polarity. This will only occur if the shapes are complementary so that they fit together. The fact is that the shape of adenine and the shape of cytosine don't fit together very well. Thymine (or uracil in RNA) fit much better with adenine, providing many more points of hydrogen bonding and a much more stable bond.

    AM
     
  4. Apr 10, 2005 #3
    hey andrew,

    thanks soo much its makes more sense now....because they are all constant at 2nm but then again there will be a lack of hydrogen bonding making the pair unstable....


    my next ? is why is duplication important? is there any reason behind the importance of duplication/replication
     
  5. Apr 10, 2005 #4
    joejo,

    "is there any reason behind the importance of duplication/replication"

    That depends on what makes something "improtant". Nature doesn't care one way or the other whether one of its processes involves the replication of extermely complex molecules. It just stumbled on to this system, and the result was living organisms (which it also doesn't give a hoot about). However, as living organisms ourselves, we tend to think that life IS important. And without replication there wouldn't be any.
     
  6. Apr 10, 2005 #5
    true true....thanks jdavel...i thought there was something scientific behind its importance...is there?
     
  7. Apr 10, 2005 #6

    Andrew Mason

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    Without the ability to duplicate, a successful molecule (ie. successful in surviving in its environment) would not proliferate. Successful molecules that duplicate themselves would proliferate. It is as simple as that.

    AM
     
  8. Apr 10, 2005 #7
    thanks guys! now i completely understand the importance of DNA
     
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