Nucleoside

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Nitrogenous base Nucleoside Deoxynucleoside
Chemical structure of adenine
Adenine
Chemical structure of adenosine
Adenosine
A
Chemical structure of deoxyadenosine
Deoxyadenosine
dA
Chemical structure of guanine
Guanine
Chemical structure of guanosine
Guanosine
G
Chemical structure of deoxyguanosine
Deoxyguanosine
dG
Chemical structure of thymine
Thymine
Chemical structure of 5-methyluridine
5-Methyluridine
m5U
Chemical structure of thymidine
Deoxythymidine
dT
Chemical structure of uracil
Uracil
Chemical structure of uridine
Uridine
U
Chemical structure of deoxyuridine
Deoxyuridine
dU
Chemical structure of cytosine
Cytosine
Chemical structure of cytidine
Cytidine
C
Chemical structure of deoxycytidine
Deoxycytidine
dC

Nucleosides are glycosylamines made by attaching a nucleobase (often referred to simply as bases) to a ribose or deoxyribose ring. Examples of these include cytidine, uridine, adenosine, guanosine, thymidine and inosine.

Nucleosides can be phosphorylated by specific kinases in the cell, producing nucleotides, which are the molecular building blocks of DNA and RNA.

Nucleosides are produced as the second step in nucleic acid digestion, when nucleotidases break down nucleotides (such as the thymine nucleotide) into nucleosides (such as thymidine) and phosphate. The nucleosides, in turn, are subsequently broken down:

- in the lumen of the digestive system by nucleosidases into nitrogenous bases and ribose (or deoxyribose).
- inside the cell by nucleoside phosphorylases into nitrogenous bases, and ribose-1-phosphate (or deoxyribose-1-phosphate).

Nucleosides differ from nucleotides by having a hydroxyl group attached to carbon number 5 (the one that isn't in the ring) of the ribose, rather than one or more phosphate groups.


See also


Nucleic acids edit
Nucleobases: Adenine - Thymine - Uracil - Guanine - Cytosine - Purine - Pyrimidine
Nucleosides: Adenosine - Uridine - Guanosine - Cytidine - Deoxyadenosine - Thymidine - Deoxyguanosine - Deoxycytidine
Nucleotides: AMP - UMP - GMP - CMP - ADP - UDP - GDP - CDP - ATP - UTP - GTP - CTP - cAMP - cGMP
Deoxynucleotides: dAMP - dTMP - dUMP - dGMP - dCMP - dADP - dTDP - dUDP - dGDP - dCDP - dATP - dTTP - dUTP - dGTP - dCTP
Nucleic acids: DNA - RNA - LNA - PNA - mRNA - ncRNA - miRNA - rRNA - siRNA - tRNA - mtDNA - Oligonucleotide

Template:Biochem-stub Note: Nucleosides can be produced by combining nucleobases with deoxyribose rings as well.

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