While proteins are the workhorses of the cell, catalyzing most of its chemical reactions, nucleic acids are the information storehouses of the cell.

Nucleic acids come in two forms, ribonucleic acid (RNA) and deoxyribonucleic acid (DNA). DNA is a permanent form of genetic information because the molecule is chemically extremely stable.

RNA is an impermanent form of nucleic acid since it is rapidly destroyed in the cell. While DNA is the repository of genetic information passed from one generation to the next, RNA is a messenger molecule which allows the instructions in the DNA to be used in specifying the sequence of the proteins to be expressed in the cell.

Nucleic acids are made of monomers called nucleotides.

Arguably, the most familiar nucleotide is adenosine triphosphate (ATP) which we will see is extremely important as a molecule used to store chemical energy.

Nucleotides are made up of three parts:

One to three phosphate groups (AMP, ADP, and ATP have 1, 2, and 3 phosphates, respectively), a sugar, ribose in RNA and deoxyribose in DNA and a planar molecule called a "base".

Bases themselves come in five kinds of two general types. Bases can be pyrimidines (consisting of one six member ring). Examples of these are cytosine (C), thymine (T), or uracil (U). Thymine is a modified form of uracil which is found in DNA; uracil is only found in RNA. Bases can also be purines (consisting of fused six and five member rings)-purines are either guanine (G) or adenine (A).

RNA consists of a linear arrangement of these nucleotides joined by phosphate groups linking successive ribose sugars. DNA consists of two strands of nucleotides, running in opposite directions, and interacting by hydrogen bonding between sets of pyrimidines and purines. A hydrogen-bonded pair of nucleotides is called a "base pair", and G will only base pair with C, and A with T.