What is nucleotide ? Defination, Types, structure, Functions


What is nucleotide:

A nucleotide is a monomer whose chains form macrocellulases called nucleic acids (DNA and RNA). Nucleotide chains are called poly nucleotides.


What is nucleotide ? Defination, Types, structure, Functions


Definition of nucleotide

A nucleotide is an organic compound that is made up of a nitrogenous base, a sugar, and phosphoric acid. Nucleotides can act as monomers in nucleic acids (DNA or RNA), forming linear chains, or act as free molecules (as is the case with ATP).


Types of Nucleotide 

There are 2 types of nucleotides: 

1. Ribonucleotides that make ribonucleic acid or RNA and 

2. Deoxyribonucleotides that make deoxyribonucleic acid or DNA.

In eukaryotic cells the cells that have a defined cell nucleus, nucleotide is found in the nucleus, whereas in prokaryotic cells (without a defined nucleus) nucleotide is found in the nucleoplasm.

In molecular biology, nucleotides, which are the base units of DNA, contain genetic information of the cell, and of RNA, which store and transfer information to the ribosome for protein synthesis, part of what is called "central dogma". Is: the pathway of information for the synthesis of proteins from DNA to RNA and then to ribosomes.


Nucleotide Nomenclature

  1. The position of the atoms in a nucleotide are specified relative to the carbon atoms in the ribose or deoxyribose sugar.
  2. Purine or pyrimidine is located on carbon 1 of the sugar.
  3. The phosphate group is on carbon 5.
  4. The hydroxyl group is attached to carbon 3 of the sugar. It can be released in the form of water as a result of the formation of the phosphodiester bond.
  5. There may be an additional hydroxyl group attached to carbon 2, if the pentose is an r.


Read : Mitochondria


Nucleotide structure

The nucleotide structure is composed of 3 parts: a nitrogenous base, a 5-carbon sugar, and a phosphate group. The poly nucleotide chain is characterized by its directionality where the tail is called the 3 'end and the head is called the 5' end.


Nitrogen base : The nitrogenous base is a ring structure containing nitrogen and may be purine or pyrimidine. Purine can be adenine (A) or divided into guanine (G) and pyrimidine cytosine (C) or uracil (U).


5 carbon sugar : Poly nucleotide chains have a central position of 5-carbon sugars that bind carbon (C) to one or more phosphate groups. Sugar is attached to its neighbors by a chain known as phosphodiester bond.

The carbon atoms in sugar are each called 1 '(one prime), 2' (two prime), 3 '(three prime), 4' (four prime, and 5 '(five prime). Nitrogen based carbon 1 And phosphate group 5 '.


Phosphate group : Phosphate groups are 2 fused rings of carbon (C) and nitrogen (N) and one or more groups can be combined in a poly nucleotide chain.

The phosphate group is attached to the first carbon (5 ') of the sugar via a phosphodiester bond.

Importantly, the structure of nucleotides is the basis of the structure of nucleic acids (DNA and RNA), therefore, they share the structure of: a nitrogenous base, a 5-carbon sugar, and a phosphate group.


Read : DNA replication 


Nucleotides and nucleic acids

  1. The nucleotide is the base unit of nucleic acids (DNA and RNA) and consists of 4 nitrogenous bases, a 5-carbon sugar, and a phosphate group.
  2. Nitrogenous bases of nucleic acids are made up of 2 purines and 2 pyrimidines. Nitrogenous bases of deoxyribonucleic acid (DNA) are: adenine (A), guanine (G), cytosine (C) and thymine (T). And ribonucleic acid (RNA) are: adenine (A), guanine (G), cytosine (C) and uracil (U).
  3. The 5-carbon sugars in DNA are called deoxyribose and the sugars in RNA are called ribose.


Nucleotides and nucleosides

The nucleoside is a part of the nucleotide that is composed of a nitrogen base and 5-carbon sugar or pentose, except for the phosphate group.

Nitrogen bases can be adenine (A), guanine (G), cytosine (C) (for DNA and RNA) thymine (T) (for DNA) or uracil (U) (for RNA). And DNA can be deoxyribose for DNA or ribose for RNA.


Read : DNA Fingerprinting


Biological functions of nucleotides:

Structural function: they are the monomers that constitute nucleic acids, which are the biomolecules involved in the conservation, reproduction, and expression of genetic information.

Energetic function: if the nucleotide joins two or three phosphates, it forms the diphosphate or triphosphate nucleotides, such as ADP, and ATP, molecules that accumulate, transport and give up energy.


Transfer of energy : Nucleotides, because their phosphate groups give it a high-energy bond, are preferred sources in cells for energy transfer. Nucleotides are in a stable state when they have only one phosphate group. Each additional phosphate group that a nucleotide possesses is in a more unstable state, and the phosphorus-phosphate bond tends, when broken by hydrolysis, to release the energy that binds it to the nucleotide.

Cells have enzymes whose function is precisely to hydrolyze nucleotides to extract the energy potential stored in their bonds. For this reason a triphosphate nucleotide is the most used source of energy in the cell. Of these, ATP (an adenine nucleotide with three phosphate groups rich in energy), is the central axis in cellular reactions for the transfer of the energy demanded. UTP (uracil + three phosphates) and GTP (guanine and three phosphates) also satisfy the energy demands of the cell in reactions with sugars and changes in protein structures, respectively.

Coenzymatic function: if the nucleotide is joined by a phosphate group to another substance, it gives non-nucleic nucleotides that act as coenzymes.



FAQs About Nucleotide 

1. What is a nucleotide structure and function?

Answer : Nucleotides are the units that make up nucleic acids. Each nucleotide is a relatively complex molecule, made up of the union of three units: a monosaccharide (a pentose), a nitrogenous base and one or more phosphate groups.


2. What is the structure of nucleotides?

Answer : RNA and DNA are polymers made up of long chains of nucleotides. A nucleotide is made up of a sugar molecule (ribose in RNA or deoxyribose in DNA) attached to a phosphate group and a nitrogenous base. The bases used in DNA are adenine (A), cytosine (C), guanine (G) and thymine (T).


3. Define Nucleotide 

Answer : Definition of nucleotide. A nucleotide is an organic compound that is made up of a nitrogenous base, a sugar, and phosphoric acid. Nucleotides can act as monomers in nucleic acids (DNA or RNA), forming linear chains, or act as free molecules (as is the case with ATP).


4. What are the types of nucleotides? 

Answer : Each nucleotide has a fixed part (a sugar and a phosphate group) and a nitrogenous base that distinguishes each type of nucleotide. In DNA there are four bases: adenine (A), cytosine (C), guanine (G) and thymine (T); and therefore four types of nucleotides.


5. What are the three components of a nucleotide?

Answer : What are nucleotides and what are their components?

  1. A nitrogenous base: for DNA formed by adenine (A), cytosine (C), guanine (G) and thymine (T).
  2. A sugar molecule: in the form of ribose in RNA or deoxyribose in DNA.
  3. A phosphate group: phosphoric acid.


6. What does 5 prime and 3 prime mean in DNA?

Answer : The chemical convention of naming the carbon atoms in the nucleotide pentose numerically gives it the 5 'end and 3' end names (generally pronounced "five prime end" and "three prime end" respectively).