Biology Forums - Study Force

The DNA molecule is made up of two strands -- each of which is a sequence of sugar and phosphate molecules linked by covalent bonds. The two chains are held together by much weaker hydrogen bonds between bases on opposite chains. The fact that the two chains are held together by weaker bonds is an important feature that helps the DNA achieve one of its primary functions. What is this function?

Hydrogen bonds are relatively weak, but many hydrogen bonds collectively increase the strength of the bond as a whole. The beauty of this is that they can be broken whenever the DNA is being copied or whenever the cells wants to produce a protein, because remember, in order for these two processes to occur, the hydrogen bonds have to transiently be broken. Once these processes are complete, the DNA strands have a tendency to want to re-anneal back to its normal double helical structure.

For the particular function, I would say to act as a template for protein transcription, i.e. from DNA to mRNA.

Just to add to your comments duddy, an individual hydrogen bond is very weak, but large numbers of hydrogen bonds are collectively strong, which explains DNA’s high stability as a molecule. The hydrogen bonds between complementary bases could break, allowing the DNA helix to unzip. Each single DNA strand could act as a template to build the complementary strand, resulting in two identical DNA molecules, one for each daughter cell (if the DNA is being copied). DNA helicase is the enzyme duddy was talking about that can unwind the double helix by breaking the hydrogen bonds between the complementary base pairs holding the two DNA strands together. Since the base pairs of the DNA are complementary, they have a natural propensity to anneal.

The ability to act as a template for the production of mRNA (the precursor of proteins).