What Does Chemical Analysis Reveal About DNA?

Deoxyribonucleic acid (DNA) is a molecule used to store and transmit genetic information in living systems. DNA was first isolated in 1870 and found to be an acid. Chemical analysis using standard wet chemistry and instrumentation has revealed that DNA is composed of carbon, hydrogen, nitrogen, oxygen and phosphorus.

Carbon

Carbon atoms are present in the ring structures of the nitrogenous bases--adenine (A), guanine (G), thymine (T) and cytosine (C)--that actually make up the genetic code. The DNA backbone comprises alternating sugar-phosphate units, with each sugar being a five-carbon ribose.

Hydrogen

Hydrogen exists at locations on the base and sugar rings, and on the base side groups to satisfy the bonding requirements of the carbon and nitrogen atoms. It also is important in establishing the polarity of the bases, which affects how the complementary pairs (A and T, C and G) are hydrogen-bonded across from each other in a DNA strand.

Nitrogen

Nitrogen exists in the rings and side groups of the nitrogenous bases. The nitrogen atoms contribute to the polarity of the bases, which affects the hydrogen bonding of complementary base pairs.

Oxygen

Oxygen is a component of all sugars and is thus present in the ribose of the DNA backbone. Oxygen is an important part of the phosphate groups in the DNA backbone. It also exists as a side group on the bases and contributes to hydrogen bonding.

Phosphorus

Phosphorus is part of the linking phosphate groups that join bases together in sequence through a ribose sugar connected to each of the nitrogenous bases on the DNA backbone.

References

• Natural Products: Nucleic Acids by William Reusch, Michigan State University