SHORT NOTE ON NUCLEIC ACID

The two major classes of nucleic acids are DNA and RNA

DNA

• Contains all the information necessary to make all biomolecules in the cell
• In simple organisms the DNA may be in the form of a single large molecule - the chromosome. This is often circular (the nucleic acid polymer is joined at the ends).
• The E. coli genome is about 5 x 10⁶ basepairs long
• In more complex organisms, the DNA is distributed among a small number of large molecules of DNA (i.e. a collection of chromosomes) - and typically linear molecules. Eukaryotes typically have two copies of each chromosome (termed a diploid genome; as opposed to a haploid genome).

RNA

• Molecules that are involved in decoding the information contained in DNA (recall the "central dogma")
• Many copies of a given RNA are made, and there are various different types of RNA molecules, including:
• Messenger RNA
• Ribosomal RNA
• Transfer RNA
• Small nuclear RNA (in eukaryotes)