The Nitrogenous Bases
The tables below show the five nitrogenous bases found in DNA and RNA. Note the similarities between the bases in each class. The bases are linked to the sugars through the nitrogen atoms shown in blue.
| The Purines | |
| adenine |
guanine |
| |
|
| The Pyrimidines | ||
| cytosine |
thymine (DNA only) |
uracil (RNA only) |
|
|
|
|
Sugars
There are two sugars found in nucleic acids
- ribose - found in ribonucleic acids
- deoxyribose - found in deoxyribonucleic acids
In nucleotides, the sugar is linked (esterified) to a phosphate group at the 3' and/or the 5' position (shown in green). The nitrogenous base is attached at the 1' position (shown in blue).
| ribose (RNA only) |
deoxyribose (DNA only) |
| |
|
If you are wondering, the carbons in the sugar are numbered 1' to 5' so as not to be confused with the numbering of the carbons in the bases.
