Chapter 4, Problem 52P

Interpretation Introduction

Interpretation:

The experiments that needs to be designed to determine the factors affecting the DNA double helix structural stability needs to be explained.

Concept introduction:

The stability of a DNA double helical structure depends on the hydrogen bonding between bases and base-stacking interaction between adjacent bases.

The bases present in a single strand of DNA have polar amido, amidino, guanidino and carbonyl groups which form hydrogen bonds with water, but when the double helical structure is formed some of the bond breaks as the bases combine to form inter-base hydrogen bonds. The change in enthalpy, in this case, is due to the difference of energy in the new hydrogen bond formed and old hydrogen bond is broken.

The stability of base stacks of the double helix depends on the DNA sequence. Some sequences are more stable than others, hence the nearest base stack is important to state the stability of the double helical structure.