What is a nucleotide?

A nucleotide is the basic unit that makes up DNA. A singular nucleotide is made up of x3 components:

  1. A base (A, T, C or G)
  2. 5 Carbon sugar (deoxyribose = DNA or ribose = RNA)
  3. Phosphate group (forms a bond between the sugar molecules in a DNA chain = phosphodiester bond) Bases There are x4 different nitrogenous bases that comprise DNA.
  4. Adenosine
  5. Cytosine
  6. Thymine
  7. Guanine

There are two groups of nucleotides pyrimidines and purines

Pyrimidines Thymine and Cytosine are the smallest of the 4 bases. With only 1 ring in their structure. In RNA, Thymine is replaced by Uracil all other bases are the same

Purines Adenosine and Guanine are purines. Their structure contains a pyrimidine ring + a smaller 5 sided ring. Therefore making a 2 ringed structure.

HA
Answered by Hannah A. Human Biology tutor

9473 Views

See similar Human Biology A Level tutors

Related Human Biology A Level answers

All answers ▸

What is a Neurones resting membrane potential and how is it maintained?


What are the three main differences between a molecule of DNA and RNA?


State three differences between the structure of DNA and the structure of RNA


What is X-linked recessive inheritance?


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning