Nucleotide Structure
- Nucleic acids such as DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are macromolecules (giant molecules)
- Like proteins (polypeptides) and carbohydrates (polysaccharides), these nucleic acids are polymers (‘poly’ meaning ‘many’)
- This means they are made up of many similar, smaller molecules (known as subunits or monomers) joined into a long chain
- The subunits that make up DNA and RNA are known as nucleotides
- Therefore DNA and RNA can also be known as polynucleotides
Nucleotides
- Nucleotides are made up of three components:
- A nitrogen-containing base (also known as a nitrogenous base)
- A pentose sugar (containing 5 carbon atoms)
- A phosphate group
The basic structure of a nucleotide
Nucleotide structure table
The nucleotides found in DNA and RNA
ATP
- Adenosine triphosphate (ATP) is the energy-carrying molecule that provides the energy to drive many processes inside living cells
- ATP is another type of nucleic acid and hence it is structurally very similar to the nucleotides that make up DNA and RNA
- It is a phosphorylated nucleotide
- Adenosine (a nucleoside) can be combined with one, two or three phosphate groups
- One phosphate group = adenosine monophosphate (AMP)
- Two phosphate groups = adenosine diphosphate (ADP)
- Three phosphate groups = adenosine triphosphate (ATP)
The structure of AMP, ADP and ATP
Examiner Tip
Don’t worry – you are not expected to know the structural formulae for the nucleotides that make up DNA and RNA or AMP, ADP and ATP (as in the diagram above)! You just need to learn the different groups that they are made up of (phosphate groups, pentose sugars and nitrogenous bases).Remember that adenine is a nitrogenous base whereas adenosine is a nucleoside (a base – adenine, attached to a pentose sugar).
