Difference between Nucleoside and Nucleotide


Nucleosides and nucleotides are both important components of nucleic acids, which are the building blocks of DNA and RNA. While they may sound similar, there are distinct differences between the two. This article aims to explain the differences between nucleosides and nucleotides in detail.


A nucleoside is composed of two main components: a nitrogenous base and a sugar molecule. The nitrogenous base can be one of the four bases found in DNA and RNA: adenine (A), guanine (G), cytosine (C), or thymine (T) in DNA, and adenine (A), guanine (G), cytosine (C), or uracil (U) in RNA. The sugar molecule in nucleosides is either ribose (in RNA) or deoxyribose (in DNA).

Components of Nucleosides

The components of nucleosides can be summarized as:

  • Nitrogenous base (A, G, C, T or U)
  • Sugar molecule (ribose or deoxyribose)

Examples of Nucleosides

Some examples of nucleosides include:

Nucleoside Nitrogenous Base Sugar Molecule
Adenosine Adenine Ribose
Deoxyadenosine Adenine Deoxyribose
Guanosine Guanine Ribose
Deoxyguanosine Guanine Deoxyribose


A nucleotide is composed of three main components: a nitrogenous base, a sugar molecule, and one or more phosphate groups. The nitrogenous base can be the same as in nucleosides: adenine (A), guanine (G), cytosine (C), thymine (T), or uracil (U). The sugar molecule is also ribose or deoxyribose, depending on whether it is RNA or DNA. The phosphate group(s) are responsible for the acidic nature of nucleotides.

Components of Nucleotides

The components of nucleotides can be summarized as:

  • Nitrogenous base (A, G, C, T or U)
  • Sugar molecule (ribose or deoxyribose)
  • Phosphate group(s)

Examples of Nucleotides

Some examples of nucleotides include:

Nucleotide Nitrogenous Base Sugar Molecule Phosphate Group(s)
Adenosine monophosphate (AMP) Adenine Ribose 1 phosphate group
Deoxyadenosine monophosphate (dAMP) Adenine Deoxyribose 1 phosphate group
Adenosine triphosphate (ATP) Adenine Ribose 3 phosphate groups
Deoxyadenosine triphosphate (dATP) Adenine Deoxyribose 3 phosphate groups

Nucleotide vs Nucleoside |Fast Differences and Comparison|

Differences between Nucleosides and Nucleotides

Now that we understand the components of nucleosides and nucleotides, let’s explore the key differences between them:

1. Phosphate Group

The presence of phosphate groups is the main distinguishing factor between nucleosides and nucleotides. Nucleosides do not contain any phosphate groups, while nucleotides have one or more phosphate groups attached to the sugar molecule.

2. Function

Nucleosides are primarily involved in the synthesis of nucleotides and nucleic acids. They act as precursors for the formation of nucleotides, which are essential for DNA and RNA synthesis. On the other hand, nucleotides play crucial roles in various cellular processes such as energy transfer (ATP), enzyme regulation (cyclic nucleotides), and signaling (cGMP and cAMP).

3. Biological Significance

Nucleosides are relatively stable molecules and are mainly present in the extracellular space. They can be transported into cells for further processing, including their conversion into nucleotides. Nucleotides, on the other hand, are highly dynamic molecules that undergo continuous synthesis and degradation within cells. They are involved in numerous cellular processes and are essential for cell growth, division, and overall function.

4. Storage and Transport

Nucleosides are not stored or transported in large quantities within cells. They are synthesized as needed from available precursors. In contrast, nucleotides are actively synthesized and stored in cells for various purposes, including energy storage (ATP) and signaling (cyclic nucleotides).

5. Roles in DNA and RNA

In DNA and RNA, nucleotides are the building blocks that form the backbone of the nucleic acid chains. Nucleosides are not directly involved in the formation of DNA or RNA. However, nucleosides can be incorporated into DNA or RNA during the synthesis process when nucleotides are added to the growing chain.


In summary, the main difference between nucleosides and nucleotides lies in the presence of phosphate groups. Nucleosides consist of a nitrogenous base and a sugar molecule, while nucleotides contain additional phosphate groups. Nucleosides serve as precursors for nucleotide synthesis, while nucleotides play a vital role in various cellular processes. Understanding the differences between nucleosides and nucleotides is crucial for comprehending the complex mechanisms of DNA and RNA synthesis and their significance in biological systems.

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