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Nucleotide

German: Nukleotid

1 Definition

Nucleotides are the basic structural unit of DNA and RNA. DNA and RNA are formed due to 5' - 3' phosphodiester bonds between nucleotides.

2 Composition

Nucleotides are composed of three different elements:

  • Nitrogenous base (purine or pyrimidine bases)
  • Pentose sugar (ribose or deoxyribose)
  • Phosphate groups

3 Structure

Nucleotides are generated by adding one up to three phosphate groups to nucleosides (nitrogenous base and pentose sugar). The phosphate group is attached to the 5th carbon atom of the pentose sugar. The differences in nomenclature of nucleotides is given by the various numbers of phosphate groups added to the nucleosides.

Nomenclature:

  • Nucleoside monophosphate
  • Nucleoside diphosphate
  • Nucleoside triphosphate

We have to distinguish between ribonucleotides and deoxyribonucleotides.

3.1 Nucleoside monophosphates

3.1.1 Deoxyribonucleotide

In the case of deoxyribonucleotides a phosphate group is added to deoxyribonucleosides.

  • Deoxyadenosine monophosphate (d-AMP)
  • Deoxyguanosine monophosphate (d-GMP)
  • Deoxythymidine monophosphate (d-TMP)
  • Deoxycytidine monophosphate (d-CMP)

3.1.2 Ribonucleotide

In the case of ribonucleotides a phosphate group is added to ribonucleosides.

  • Adenosine monophosphate (AMP)
  • Guanosine monophosphate (GMP)
  • Uridine monophosphate (UMP)
  • Cytidine monophosphate (CMP)

3.2 Nucleoside polyphosphates

The nucleoside polyphosphates are generated by adding one or two phosphates to the nucleoside monophosphates. These bonds between the phosphate groups are high energy bonds. ATP which is the most important nucleoside polyphosphate provied energy due to these bonds to the human body.

3.3 Cyclic nucleotides

The cyclic shape in cyclic nucleotides is due to two connections between the pentose sugar (3rd and 5th carbon atom) and a phosphate. The two most important cyclic nucleotides are cAMP and cGMP. They act as second messenders within the body.

4 References

  • [1] retrieved on 06 June 2016
  • Basics in descriptive biochemistry/Tiberiu Nistor
  • [2] retrieved on 06 June 2016

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