Nucleic acids are macromolecules containing hydrogen, oxygen, nitrogen, carbon and phosphorus. The function of nucleic acids is to store and transmit genetic information (chemical instructions about how living things should form and operate). You will learn much more about nucleic acids in a future unit of study, so this section will be brief.

The monomer units of nucleic acids are called nucleotides. One nucleotide consists of a 5-carbon sugar, a phosphate group and a nitogen base.

Two examples of nucleic acids are deoxyribonucleic acid (DNA), and ribonucleic acid (RNA). Each of these macromolecules carries all or part of the genetic code for a cell. Each is made up of nucleotides.

Look at the diagram above. Note that there are five possible nitrogenous bases that can create a nucleotide (cytosine, guanine, adenine, uracil, and thymine). There are also two possible sugars – deoxyribose (Deoxyribonucleic Acid or DNA) and ribose (Ribonucleic Acid, or RNA).

It is not visible in the diagram above, but hydrogen bonds hold the bases together at the center of DNA’s rungs (where the bright colors meet).

Energy-Carrier Molecules

It is also worth mentioning that some modified versions of nucleotides can serve as energy carriers for cells in living things. Two of the most common are ATP (Adenosine Triphosphate) and NADH (Nicotinamide Adenine Dinucleotide), but we’ll just call them ATP and NADH for short.  These energy carrier molecules unite all organisms on earth because all organisms have to have a way to store and then use energy. Take a look at ATP below and be sure that you notice its similarities to the nucleotide above. 

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