DNA and Hydrogen Bonds
Date: October 2007
can you please explain why hydrogen bonds are used to hold
the double helix DNA together. why would covalent bonds have a poor chance?
Covalent bonds would do a fantastic job of holding the helix together -- too
good a job, in fact. An organism is continually unzipping DNA to make
proteins (RNA attaches to the unzipped DNA during a process called
'transcription'). If the DNA was held together with covalent bonds, the
organism would need to use a lot more energy to break those bonds, and a lot
more energy to recreate the bonds. This would be extremely inefficient, and
may make errors happen more in DNA. Depending on the type of covalent bond,
the shape of the DNA molecule may change or be more rigid. If DNA's shape
were to change, it might work as well, but it might not work at all.
Certainly the enzymes that exist now are specialized for DNA as it is --
they would not work with a differently shaped DNA molecule.
Hope this helps,
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Update: June 2012