Biology Reference
In-Depth Information
Figure 16.2.
Structures of adenosine, guanine, cytosine, thymine, and
urasil.
The backbone of DNA and RNA is hydrophilic due to pentose
group. At pH 7, the phosphate groups of DNA and RNA are ionized
and negatively charged. The purine and pyrimidine bases are
hydrophobic.
Therearetwoimportantmodesofinteractionsbetweenbasesin
nucleic acids:
1.
Hydrophobic stacking interactions
.
In this type of interaction, the planar and rigid bases are
positioned with the planes of their rings parallel. It involves
combination of van der Waals and dipole-dipole interactions to
minimize water contact with bases thus stabilizing the three-
dimensionalstructure of nucleicacids.
2.
Hydrogen bonds
.
This bond involves the amino and carboxyl groups and is
important for complementary association of two nucleic acid
