DNA is the abbreviation for deoxyribonucleic acid. It is the central molecule in heredity in that it is copied and passed on to new cells during the cell replication cycle. Each monomer unit of DNA is called a nucleotide which itself is composed of a ribose sugar (without one of the hydroxyl groups) and one of four different bases molecules: adenine, guanine, cytosine, and thymine. The different combinations of these 4 different bases is what creates all of the instructions the cell needs to produce proteins in order for life to function. The DNA of most cells is found in the nucleus of the cell. It is not surprising, since DNA plays such a vital role to life, that it would be found in the central part of the cell where it would be the most protected.