Threose

Threose

Threose is a four-carbon monosaccharide or carbohydrate with molecular formula C4H8O4. It has a terminal aldehyde group rather than a ketone in its linear chain, and so is considered part of the aldose family of monosaccharides...

 nucleic acid (TNA) is a polymer

Polymer

A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...

 similar to DNA

DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

 or RNA

RNA

Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....

 but differing in the composition of its "backbone". TNA is not known to occur naturally; they are synthesized chemically

Oligonucleotide synthesis

Oligonucleotide synthesis is the chemical synthesis of relatively short fragments of nucleic acids with defined chemical structure . The technique is extremely useful in current laboratory practice because it provides a rapid and inexpensive access to custom-made oligonucleotides of the desired...

.

DNA and RNA have a deoxyribose

Deoxyribose

Deoxyribose, more, precisely 2-deoxyribose, is a monosaccharide with idealized formula H---3-H. Its name indicates that it is a deoxy sugar, meaning that it is derived from the sugar ribose by loss of an oxygen atom...

 and ribose

Ribose

Ribose is an organic compound with the formula C5H10O5; specifically, a monosaccharide with linear form H––4–H, which has all the hydroxyl groups on the same side in the Fischer projection....

 sugar backbone, respectively, whereas TNA's backbone is composed of repeating threose

Threose

Threose is a four-carbon monosaccharide or carbohydrate with molecular formula C4H8O4. It has a terminal aldehyde group rather than a ketone in its linear chain, and so is considered part of the aldose family of monosaccharides...

 units linked by phosphodiester bond

Phosphodiester bond

A phosphodiester bond is a group of strong covalent bonds between a phosphate group and two 5-carbon ring carbohydrates over two ester bonds. Phosphodiester bonds are central to all known life, as they make up the backbone of each helical strand of DNA...

s. The threose molecule is easier to assemble than ribose making it a possible precursor to RNA.

DNA-TNA hybrid chains have been made in the laboratory using DNA polymerase.

TNA can hybridize with RNA and DNA in a sequence-specific manner; this capability and chemical simplicity suggests that TNA could have preceded RNA as genetic material.

See also

• Oligonucleotide synthesis
  Oligonucleotide synthesis
  Oligonucleotide synthesis is the chemical synthesis of relatively short fragments of nucleic acids with defined chemical structure . The technique is extremely useful in current laboratory practice because it provides a rapid and inexpensive access to custom-made oligonucleotides of the desired...
  
  
• Abiogenesis
  Abiogenesis
  Abiogenesis or biopoesis is the study of how biological life arises from inorganic matter through natural processes, and the method by which life on Earth arose...
  
  
• Glycol nucleic acid
• Peptide nucleic acid

External links

• "Was simple TNA the first nucleic acid on Earth to carry a genetic code?", New Scientist

  ORIGIN OF LIFE: A Simpler Nucleic Acid", Leslie Orgel

  Leslie Orgel

  Leslie Eleazer Orgel FRS was a British chemist.Born in London, England, Orgel received his B.A. in chemistry with first class honours from Oxford University in 1949...