Nucleotide: Definition, Function, and Examples

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Nucleotide Definition

A nucleotide is a kind of chemical molecule that makes up DNA and RNA. They have a role in cell signalling, metabolism, and enzyme processes, among other things.

A nucleotide is composed of three main components: a phosphate group, a 5-carbon sugar, and a nitrogenous base. The 4 nitrogenous bases of Genetic material are adenine, cytosine, guanine, and thymine. RNA has uracil instead of thymine.

The genetic material of all known living organisms is made up of nucleotides in a chain. Aside from storing genetic data, they also serve as messengers and energy-moving molecules. A codon is a three-nucleotide sequence in DNA that tells the cell’s proteins to bind a certain protein to a series of nucleotides defined by the remainder of the DNA.

Even the machinery may be told where to halt and start the process thanks to special codons. DNA translation is the process of converting information from DNA into protein language. This chain of amino acids can then be folded correctly and serve one of the cell’s numerous tasks.

Nucleotide Structure

The structure of nucleotides is basic, but the structure they may produce when combined is complicated. DNA molecule is made up of two strands that wrap around each other and establish hydrogen bonds in the centre to provide stability. Each nucleotide has a unique structure that allows for this creation.

Nitrogenous Base

The major information-carrying component of the nucleotide structure is the nitrogenous base. Because they have different exposed functional groups, these molecules have different abilities to interact with one another.

The concept arrangement has the largest number of hydrogen bonds between the nucleotides involved, as seen in the picture. Only one nucleotide can interact with another due to the structure of the nucleotide.

Thymine bonds to adenine, and guanine bonds to cytosine, as shown in the picture above. This is the appropriate and standard setup.

The structure twists as a result of this even construction, which is smooth provided there are no mistakes. Proteins can attach to uneven areas within the structure, which is one way they might repair damaged DNA.

When hydrogen bonds between opposing nucleotide molecules do not form, uneven patches form.

One nucleotide will be removed and replaced by another by the protein. Because the genetic strands are duplicated, mistakes like these can be repaired with a great degree of precision.


The sugar is the nucleotide’s second component. The sugar is the same regardless of the nucleotide. The distinction between DNA and RNA is significant. Deoxyribose is the 5-carbon sugar in DNA, while ribose is the 5-carbon sugar in RNA.

This is how genetic molecules get their names: deoxyribonucleic acid is the entire name for DNA, and ribonucleic acid is the complete name for RNA.

The sugar can connect with the phosphate group of the following molecule because of its exposed oxygen. The sugar-phosphate backbone is formed when they establish a connection.

Because the covalent connections formed by this structure are significantly stronger than the hydrogen bonds formed by the two strands, it imparts stiffness to the structure.

When proteins digest and transpose DNA, they separate the strands and read just one side at a time. When they die, the opposing nucleotide bases attract each other, causing the strands of genetic material to recombine. The sugar-phosphate backbone remains intact throughout.

Phosphate Group

The phosphate group, the last component of the nucleotide structure, is presumably known from another essential molecule, ATP. The energy molecule adenosine triphosphate, or ATP, is used by most life on Earth to store and transmit energy between processes.

Three phosphate groups are found in ATP, each of which may store a significant amount of energy in their bonds. Because the phosphate group and the sugar molecule interact, the bonds produced within a nucleotide are known as phosphodiester bonds, as opposed to ATP.

DNA polymerase assembles the right nucleotide bases and begins arranging them against the chain it is reading during DNA replication. The work was completed by DNA ligase, which formed a phosphodiester link between the sugar molecule of one base and the phosphate group of the next.

This forms the foundation of a new genetic molecule that may be handed down to future generations. All of the genetic information required for cells to operate is included in DNA and RNA.

Nucleotide Examples

Adenine: Purines are one of two types of nitrogenous bases. Adenine belongs to the purine family. Purines have a structure that is made up of two rings. Adenine binds to thymine in DNA. Adenine binds to uracil in RNA. As previously mentioned, the nucleotide adenine is used as a base in adenosine triphosphate. Three phosphate groups can be connected from there. This enables the bonds to store a significant amount of energy. The bonds in ATP are extremely strong for the same reason that the sugar-phosphate backbone is. It may be transmitted to other processes and molecules when coupled with specific enzymes that have developed to release the energy.

Guanine: Guanine, like adenine, is a purine nucleotide with two rings. In both DNA and RNA, it binds to cytosine. Guanine forms three hydrogen bonds with cytosine, as shown in the picture above. The cytosine-guanine link is therefore somewhat stronger than the thymine-adenine bond, which only has two hydrogen bonds.

Cytosine: Pyrimidines are the other nucleotide class. Cytosine is a pyrimidine nucleotide with a single ring shape. In both DNA and RNA, cytosine binds to guanine. The nucleotide guanine forms a strong bond with the nucleotide adenine.

Thymine: Thymine, like cytosine, is a pyrimidine nucleotide with only one ring. In DNA, it forms a link with adenine. RNA does not include thymine. It only makes two hydrogen bonds with adenine in DNA, making it the weaker of the two.

Uracil: Uracil is a pyrimidine as well. Uracil is inserted where a thymine would typically be during DNA to RNA transcription. Though uracil has certain unique advantages and drawbacks, the cause for this is unknown. Because uracil is short-lived and can breakdown into cytosine, most organisms do not employ it in their DNA. However, because RNA is a short-lived molecule, uracil is the preferred nucleotide.

Nucleotide Function

A nucleotide can serve a variety of purposes in addition to being the fundamental unit of genetic material for all living organisms. A base in another molecule, such as adenosine triphosphate (ATP), the cell’s main energy molecule, can be a nucleotide.

They’re also present in coenzymes like NAD and NADP, which are derived from ADP and are employed in a variety of chemical processes in metabolism. Another nucleotide-containing molecule is cyclic AMP (cAMP), a messenger molecule involved in a variety of activities, including metabolic control and the delivery of chemical signals to cells.

Nucleotides are not only the building blocks of life, but also the building blocks of many other compounds that make life possible.

Nucleotide Citations
  • Nucleotide second messengers in bacterial decision making. Curr Opin Microbiol . 2020 Jun;55:34-39.
  • Nucleotide Transport and Metabolism in Diatoms. Biomolecules . 2019 Nov 21;9(12):761.
  • Regulation of mammalian nucleotide metabolism and biosynthesis. Nucleic Acids Res . 2015 Feb 27;43(4):2466-85.
  • Nucleotide Sugars in Chemistry and Biology. Molecules . 2020 Dec 6;25(23):5755.
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