Nucleic Acid

Nucleic Acid

1. Are long chainlike molecules composed of a series of nearly identical building blocks called nucleotides.

   • Each nucleotide consists of a nitrogen-containing aromatic base attached to a pentose (five-carbon) sugar, which is in turn attached to a phosphate group.

2. Nucleic acids are the main information-carrying molecules of the cell, and, by directing the process of protein synthesis, they determine the inherited characteristics of every living thing.

3. The two main classes of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

   • DNA is the master blueprint for life and constitutes the genetic material in all free-living organisms and most viruses.
     • DNA has a unique 'double helix' shape, like a twisted ladder.
   • RNA is the genetic material of certain viruses.
     • It is also found in all living cells, where it plays an important role in certain processes such as the making of proteins.

4. Nucleotides are synthesized from readily available precursors in the cell. The ribose phosphate portion of both purine and pyrimidine nucleotides is synthesized from glucose via the pentose phosphate pathway.

   • The six-atom pyrimidine ring is synthesized first and subsequently attached to the ribose phosphate. The two rings in purines are synthesized while attached to the ribose phosphate during the assembly of adenine or guanine nucleosides. In both cases the end product is a nucleotide carrying a phosphate attached to the 5′ carbon on the sugar.

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