Question

H bonds individually are very weak and yet the strands of a DNA double helix can generally be separated only by very high temperatures approaching 100 degrees celsius. How does the weakness of H bonds account for such a strong interaction?

a. H bond strength decreases with the distance it covers
b. H bond strength increases with the distance it covers
c. H bond strength is additive and the many H bonds holding the strands together make it stable
d. Four H bonds is enough to enhance the strength of the interactions of the two DNA strands
e. H bond strength is proportional to the molecular weights of the interacting molecules

Answer 1

DNA's double helix structure is stable due to the cumulative effect of multiple weak hydrogen bonds, whose additive nature provides significant overall stability. High temperatures or chemical denaturation can disrupt these bonds, a process which is reversible under normal conditions.

Step-by-step explanation:

The stability of DNA's double helix structure is attributed to the collective strength of many weak hydrogen bonds. Individually, a hydrogen bond is weak, especially when compared to a covalent bond, and can be easily broken. However, in DNA, there are millions of these hydrogen bonds between the nitrogenous bases that contribute to a strong overall stabilizing effect. This robust interaction is necessary for the integrity of the DNA structure and for its ability to withstand the cellular environment while still facilitating crucial biological processes such as replication and transcription. While each hydrogen bond is relatively weak, their strength is additive, meaning that the overall stability of the DNA molecule is greatly enhanced by having many such bonds in parallel.

At high temperatures or under certain chemical conditions, DNA strands can be denatured as these hydrogen bonds are broken; the process is reversible through annealing when conditions return to normal.