What is DNA made of or components of DNA?
- DNA is a polymer.
- Monomers are deoxyribonucleotides (we will call nucleotides).
- DNA components are
- Nucleotides and Nucleosides
- Nitrogen bases
- Sugar
- Phosphate
Nucleotides and Nucleosides
| Description | Nucleotides | Nucleosides |
|---|---|---|
|
Each nucleotide is made up of three parts – a sugar, a phosphate and a nitrogen base. [phosphate covalently bonded to 3’ or/and 5’ hydroxyl group(s)] DNA contains four types of nucleotides. Type of nucleotide depends on nitrogen base. |
Each nucleoside is made up of two parts – a sugar and a nitrogen base. [No phosphate] | |
| Component Nitrogen base | Name of Nucleotide | Name of Nucleoside |
| Adenosine (A) | Deoxyadenylate | Deoxyadenosine |
| Thymine (T) | Deoxyguanylate | Deoxyguanosine |
| Guanine (G) | Deoxycytidylate | Deoxycytidine |
| Cytosine (C) | Deoxythymidylate | Deoxythymidine |
Nitrogen bases
- There are 4 different bases in a DNA molecule, two purines and two pyrimidines.
- Purines – adenine and guanine
- Pyrimidines – cytosine and thymine
- Sequence of nitrogen bases determine what biological information is written in DNA strand which is used to for build and maintain an organism.
| N-base group | Purines | Pyrimidines |
|---|---|---|
| Members | Adenine and Guanine | Cytosine and Thymine |
| Derivative of pyrimidines, two ringed structure | One ringed structure | |
| Larger than pyrimidines | Smaller than purines | |
| Base pairs | adenine – thymine and cytosine – guanine | |
Sugar
- DNA contains Β – D 2’-deoxyribose sugar
- Named 2’-deoxyribose as hydroxyl group at 2’ carbon is missing (as compared to ribose sugar)
- It is pentose sugar, named so as it contains 5 carbons
- Prefix D – refer the configuration of sugar, because of the presence of asymmetric carbon atom
- Hydroxyl groups from 3’ and 5’ carbon link to phosphate group to build DNA backbone.
Phosphate (phosphoric acid)
- Out of three reactive hydroxyl groups of the phosphoric acid, two are used for DNA backbone formation or DNA chain formation.
- It links to 3’ carbon of one sugar and 5’ carbon of another one.
- The third one gives the DNA an acidic property
To know structure of DNA go though page DNA double helix.