Nucleosides are fundamental components of nucleotides, which are the building blocks of nucleic acids like DNA and RNA.
Components of Nucleosides
A nucleoside is composed of two main components:
1. Sugar Molecule (Pentose Sugar):
The sugar molecule in a nucleoside is a pentose sugar, meaning it has five carbon atoms.
In DNA, the sugar is deoxyribose, and in RNA, it is ribose.
2. Nitrogenous Base:
The nitrogenous base is a crucial component determining the specificity and function of the nucleoside.
The bases can be purines (adenine, guanine) or pyrimidines (cytosine, thymine, uracil).
Examples of Nucleosides
1. Adenosine:
Sugar: Ribose
Nitrogenous Base: Adenine
Example in DNA: Deoxyadenosine (with deoxyribose)
Example in RNA: Adenosine (with ribose)
2. Guanosine:
Sugar: Ribose
Nitrogenous Base: Guanine
Example in DNA: Deoxyguanosine (with deoxyribose)
Example in RNA: Guanosine (with ribose)
3. Cytidine:
Sugar: Ribose
Nitrogenous Base: Cytosine
Example in DNA: Deoxycytidine (with deoxyribose)
Example in RNA: Cytidine (with ribose)
4. Thymidine:
Sugar: Deoxyribose
Nitrogenous Base: Thymine
Example in DNA: Deoxythymidine (with deoxyribose)
Not present in RNA.
5. Uridine:
Sugar: Ribose
Nitrogenous Base: Uracil
Example in RNA: Uridine (with ribose)
Not present in DNA.
Components of Nucleotides
A nucleotide is a more complex molecule compared to a nucleoside. It consists of three main components:
1. Sugar Molecule (Pentose Sugar):
The sugar in a nucleotide is also a pentose sugar, either deoxyribose (in DNA) or ribose (in RNA).
2. Nitrogenous Base:
The nitrogenous base can be a purine (adenine, guanine) or a pyrimidine (cytosine, thymine, uracil).
3. Phosphate Group:
The phosphate group is a crucial component providing the nucleotide with a negative charge.
It is attached to the 5′ carbon of the sugar molecule.
Examples of Nucleotides
1. Deoxyadenosine Monophosphate (dAMP):
Sugar: Deoxyribose
Nitrogenous Base: Adenine
Phosphate: Monophosphate
2. Guanosine Triphosphate (GTP):
Sugar: Ribose
Nitrogenous Base: Guanine
Phosphate: Triphosphate
3. Cytidine Diphosphate (CDP):
Sugar: Ribose
Nitrogenous Base: Cytosine
Phosphate: Diphosphate
4. Deoxythymidine Triphosphate (dTTP):
Sugar: Deoxyribose
Nitrogenous Base: Thymine
Phosphate: Triphosphate
5. Uridine Monophosphate (UMP):
Sugar: Ribose
Nitrogenous Base: Uracil
Phosphate: Monophosphate
Nucleotides serve as the monomers of nucleic acids, where the sequential arrangement of nucleotides forms DNA and RNA, carrying genetic information and facilitating various cellular processes.
