What would be the disadvantage of having two DNA strands held by covalent bonds between the nucleotides?

DNA is held together as a duplex by hydrogen bonds. This would appear to be a fragile state of affairs for such an important molecule.

A. Why is this not the case?

B. What would be the disadvantage of having two DNA strands held together by covalent bonds between the complementary nucleotides?What would be the disadvantage of having two DNA strands held by covalent bonds between the nucleotides?
There are a great many hydrogen bonds holding the structure together, which is in fact very strong. If you doubt the strength of hydrogen bonds, find a load of sawdust, mix it to a paste with water, then freeze it, and try to break it with a hammer. Hydrogen bonds are pretty strong!



If they were covalently bonded replication would be very difficult and require very large amounts of energy.What would be the disadvantage of having two DNA strands held by covalent bonds between the nucleotides?
The first answer got it perfect.



Not only would replication require a huge amount of energy in order to unzip the duplex, but so would transcription. The transcriptional machinery must unwind the DNA to read the sense strand.