Threose nucleic acid

Threose nucleic acid (TNA) is an artificial genetic polymer invented by Albert Eschenmoser. TNA has a backbone structure composed of repeating threose sugars linked together by phosphodiester bonds. Like DNA and RNA, TNA can store genetic information in strings of nucleotide sequences (G, A, C, and T). TNA is not known to occur naturally and is synthesized chemically in the laboratory under controlled conditions. It is believed by some that TNA could be an evolutionary pathway to RNA.

TNA has generated great interest in synthetic biology because TNA polymers are resistant to nuclease degradation. This property, coupled with its ability to undergo Darwinian evolution in a test-tube, provide a possible path to biologically stable molecules with relevance in material science and molecular medicine.

TNA can self-assemble by Watson-Crick base pairing into duplex structures that closely approximate the helical geometry of A-form RNA. TNA can also form base pairs complementary to strands of DNA and RNA, which makes it possible to share information with natural genetic polymers. This capability and chemical simplicity suggests that TNA could have preceded RNA as a genetic material.

Nucleic acid

Nucleic acids are biopolymers, or large biomolecules, essential for all known forms of life. Nucleic acids, which include DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), are made from monomers known as nucleotides. Each nucleotide has three components: a 5-carbon sugar, a phosphate group, and a nitrogenous base. If the sugar is deoxyribose, the polymer is DNA. If the sugar is ribose, the polymer is RNA. When all three components are combined, they form a nucleic acid. Nucleotides are also known as phosphate nucleotides.

Nucleic acids are among the most important biological macromolecules (others being amino acids/proteins, sugars/carbohydrates, and lipids/fats). They are found in abundance in all living things, where they function in encoding, transmitting and expressing genetic information—in other words, information is conveyed through the nucleic acid sequence, or the order of nucleotides within a DNA or RNA molecule. Strings of nucleotides strung together in a specific sequence are the mechanism for storing and transmitting hereditary, or genetic information via protein synthesis.