A nucleotide is the basic building block (monomer) of nucleic acids like DNA and RNA. Each nucleotide has three main components:
- Nitrogenous Base:
- This is the part that carries genetic information.
- It contains nitrogen and comes in different types:
- In DNA: Adenine (A), Thymine (T), Guanine (G), Cytosine (C)
- In RNA: Adenine (A), Uracil (U) (instead of Thymine), Guanine (G), Cytosine (C)
- The sequence of these bases forms the genetic code.
- Pentose Sugar (5-Carbon Sugar):
- This sugar connects the base to the phosphate group.
- In DNA, the sugar is deoxyribose (it lacks one oxygen atom).
- In RNA, the sugar is ribose (it has one more oxygen atom).
- Phosphate Group:
- The phosphate gives the nucleotide its acidic property.
- It links one nucleotide to another, forming the sugar-phosphate backbone of DNA or RNA.
- One, two, or three phosphate groups may be attached (for example, ATP has three).
In short:
A nucleotide is made of —
- a nitrogen base,
- a sugar (ribose or deoxyribose), and
- a phosphate group.
These three parts join together to form the repeating units that build nucleic acids like DNA and RNA — the molecules that store and transmit genetic information.