Difference Between Nucleotide and Nucleoside

Difference Between Nucleotide and Nucleoside: Nucleotides and nucleosides are nitrogenous bases with ribose sugar attached through a glycosidic bond. Therefore, a nucleoside is a nitrogenous base with ribose sugar attached through an β-glycosidic bond. In contrast, a nucleotide is a nucleoside with a phosphate group attached to ribose sugar through a phosphodiester bond.

Difference between Nucleotide and Nucleoside

To understand the difference between a nucleoside and a nucleotide, we need to understand the basic components of these structures. These structures are basically comprised of nitrogenous bases (Heterocyclic N- containing compounds) attached with ribose or deoxyribose sugar through an β-glycosidic bond. Furthermore, the following points are explained to understand these basic structures.

Nitrogenous Bases in Nucleotide and Nucleoside

These are the nitrogen-containing heterocyclic biological compounds that become the hereditary material’s basic structure (DNA or RNA). On the basis of the cyclic structure, they contain these compounds could be divided into broad categories.

• Purins are the heterocyclic N-containing compounds comprising two heterocyclic structures (pyrimidine ring fused with imidazole ring)—the general chemical formula for a typical purine ring structure in C₅H₄N₄. Examples of purine: Adenine, Guanine, Inosine, and Intermediate purines(Hypoxanthine, Xanthine).

Purine nitrogenous base	Function
Adenine	Adenine is known to be found in DNA as well as in RNA, base pairs by the formation of two hydrogen bonds with Thymine in DNA and Uracil in RNA.
Guanine	Guanine is known to be found in DNA and RNA, base pairs by forming three hydrogen bonds with Cytosine in both DNA and RNA.
Inosine	Inosine is known to be found very specifically in the tRNA anti-codon arm and bases with all nitrogenous bases i.e., Adenine, cytosine, and uracil, except guanine.

• Pyrimidines are heterocyclic N-containing compounds comprised of a single heterocyclic ring i.e., a pyrimidine ring—the general chemical formula for a typical pyrimidine ring structure is C₅H₅N. Examples of pyrimidine: Thymine, Uracil, and Cytosine.

Pyramidine nitrogenous base	Function
Thymine	Thymine is known to be found in DNA and base pairs by the formation of two hydrogen bonds with Adenine.
Uracil	Uracil is known to be found in RNA and base pairs by the formation of two hydrogen bonds with Adenine.
Cytosine	Cytosine is known to be found in DNA as well as RNA and base pairs by the formation of three hydrogen bonds with Guanine.

Sugars present in Nucleoside and Nucleotide

Ribose and deoxyribose are the pentasaccharides that are present in RNA and DNA, respectively. These sugar structures are attached to the purine(through C1’of sugar and N9 of purine base) and pyrimidines(through C1’of sugar and N1 of pyrimidine base) through a β-glycosidic bond.

• A marked difference can be seen in the structure of ribose and deoxyribose in the absence of C2′ OH(Hydroxyl), and instead of this OH group, a Hydrogen atom is attached to the C2′. The following pictorial presentation can help you to distinguish between both.

Nucleoside

The formation of nucleosides occurs in forming a β-glycosidic bond between purine through C1’of sugar and N9 of the purine base and pyrimidines through C1’of sugar and N1 of the pyrimidine base. The following image can help you to understand the bond pattern.

Nucleotide

Nucleotide formation occurs due to the attachment of inorganic phosphate ions at the C5′ of either ribose or deoxyribose sugar. The bond which is majorly involved in this linkage is the phosphodiester bond. The nucleotides are now become active and now can be used as energy currency such as ATP(Adenosine triphosphate), GTP(Guanosine triphosphate), and a building block of hereditary material such as DNA and RNA.

FAQs on Nucleotide and Nucleoside

Q1: What are nucleotides and nucleosides?

Answer:

Nucleosides is a basic component of nucleotide composed of a nitrogenous base and a ribose/deoxyribose sugar linked together by a β-glycosidic bond, whereas the nucleotide is a structure comprised of nucleoside and an inorganic phosphate group attached to the C5′ of ribose sugar with phosphodiester bond.

Q2: Is ATP a nucleotide or nucleoside?

Answer:

ATP stands for Adenosine triphosphate, the name itself suggests that the phosphate group is attached to the sugar. so it should be considered as a nucleotide.