5 Difference Between Nucleotide And Nucleoside With Examples

Nucleoside is a structural sub-unit of nucleic acids, the heredity-controlling component of all living cells, consisting of a molecule of sugar linked to a nitrogen-containing organic ring compound. Nucleosides are usually obtained by chemical or enzymatic decomposition of nucleic acids. In nucleosides, the sugar is either ribose or deoxyribose and the nitrogen-containing compound is either a pyrimidine (cytosine, thymine or uracil) or a purine (adenine or guanine).

A nucleotide is an organic molecule that is the building block of DNA and RNA. A nucleotide is made up of three parts: a 5-carbon sugar, a phosphate group and a nitrogenous base. Other than storage of genetic material, nucleotides serve as messengers and energy moving molecules. Both nucleotide and nucleoside form the key structural elements of a genetic material. However, they may be having almost similar components but structurally, they are different.

In this article, get to understand the difference between a nucleoside and a nucleotide. The basis of comparison include: medical relevance, chemical composition, structure and role in nucleic acids.

The Difference

A nucleoside consists of a nitrogenous base covalently attached to a sugar (ribose or deoxyribose) but without the phosphate group. On the other hand, a nucleotide consists of a nitrogenous base, a sugar (ribose or deoxyribose) and one to three phosphate groups.
Several nucleoside analogues are used in medicine as antiviral or anticancer agents whereas dysfunctional nucleotides lead to accumulation of DNA damage, eventually leading to the onset of cancer.
Nucleoside undergoes phosphorylation to form nucleotides whereas nucleotide forms covalent bonds with other nucleotides to form the nucleic acid strand.
Nucleoside=Pentose sugar + nitrogenous base (nucleobase) whereas Nucleotide=Nucleoside + one or more phosphate groups.
Examples of nucleosides include: Cytidine, Uridine, Adenosine, Guanosine and Thymidine whereas examples of nucleotides include: 5’-Cytidine monophosphate, 5’-Uridine monophosphate, 5’-Adenosine monophophate, 5’-Guanosine monophosphate and 5’- Thymidine monosphoshate.

Also Read: Difference Between RNA And DNA

Nucleotide Vs. Nucleoside In Tabular Form

BASIS OF COMPARISON	NUCLEOSIDE	NUCLEOTIDE
Structure	A nucleoside consists of a nitrogenous base covalently attached to a sugar (ribose or deoxyribose) but without the phosphate group.	A nucleotide consists of a nitrogenous base, a sugar (ribose or deoxyribose) and one to three phosphate groups.
Medical Relevance	Several nucleoside analogues are used in medicine as antiviral or anticancer agents.	Dysfunctional nucleotides lead to accumulation of DNA damage, eventually leading to the onset of cancer.
Role In Nucleic Acids	Nucleoside undergoes phosphorylation to form nucleotides.	Nucleotide forms covalent bonds with other nucleotides to form the nucleic acid strand.
Chemical Composition	Nucleoside=Pentose sugar + nitrogenous base (nucleobase).	Nucleotide=Nucleoside + one or more phosphate groups.
Examples	Examples of nucleosides include: Cytidine, Uridine, Adenosine, Guanosine Thymidine	Examples of nucleotides include: 5’-Cytidine monophosphate, 5’-Uridine monophosphate, 5’-Adenosine monophophate, 5’-Guanosine monophosphate 5’- Thymidine monosphoshate.

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