Question

What is the difference between a nucleoside and a nucleotide?

Answer 1

Hint: Nucleic acid is the biologically important polymers that are formed by the repeating units. These repeating units are called nucleotides. Nucleotides are further made of nucleosides and phosphate groups. Nucleoside and nucleotide are basic structural units of DNA and RNA. These are made of a nitrogen-containing base (purine and pyrimidine), sugar (ribose ), and phosphate.

Complete answer:
Nucleoside: The molecules in which one of the nitrogen bases (purine and pyrimidine) is bonded with a sugar molecule is called a nucleoside. The general representation of nucleoside is as follows,
$\text{ Base + Sugar = Nucleoside }$
The nucleoside of RNA and DNA are differed in two aspects: base in place of
1) The sugar in the RNA nucleoside is ribose while the sugar in the DNA nucleoside is deoxyribose.
2) The nucleoside of RNA contains uracil base in place of thymine present in DNA.
Nucleosides are named depending upon the base present.

Nucleotide: When the phosphate group is attached to the nucleoside, the compound formed is called as nucleotide.in other words, a nucleotide is a phosphate ester of nucleoside and consist of a purine or pyrimidine base, the 5-carbon sugar, and one or more phosphate groups.
$\text{ Base + sugar + Phosphate = Nucleotide }$
Thus, a nucleotide contains a sugar unit linked to the nitrogen base and phosphate group unit. The difference between the nucleotide and nucleoside is as shown below,

	nucleoside	Nucleotide
1.	Nucleosides are nucleosides which contain sugar and base without a phosphate group.$\text{ Base + Sugar = Nucleoside }$	Nucleotides are molecules which contain sugar and base on a phosphate group.$\text{ Base + Sugar + Phosphate = Nucleotide }$
2.	Nucleosides are used as the medicinal agent against the virus and cancer-causing agents.	Nucleotides are a major cause of cancer-causing agents.
3.	Nucleosides are used to encoding, transmitting, and carrying genetic information.	Nucleotides are used to build nucleic acids such as DNA and RNA.
4.	Example of nucleosides are:Adenosine (A) , guanosine (G) , Cytidine (C) , Thymidine (T) , Uridine (U)	Examples of nucleotides are: Adenosine monophosphate (AMP) , deoxyadenosine monophosphate (dMP) , Adenosine triphosphate (ATP) ,etc.

Note: Note that nucleosides containing pyrimidine bases are much more stable to hydrolysis than nucleosides containing purine bases. Hence, pyrimidine nucleosides are usually hydrolysed after hydrogenating.