[CHEKAL]

are nucleobases such as thymine amides? as im doing a report on how nature has selected to use the amide functionality, im explaining that its fairly unreactive to substitution as the as the carbonyl group is less reactive.

thanks

[JGK]

No, amides are acyl substituted derivatives of ammonia. In purines and pyrimidines the nitrogen atoms have no acyl substitutions

[Babcock_Hall]

I would define amides as acyl derivatives of amines, not just ammonia.  I think the question about the common bases in DNA or RNA is not simple.  It could be argued that guanine is an amide, but I would be tempted to say that cytosine is derivative of urea.  Adenine is neither of these, having no oxygens.  On the other hand sphingolipids have a nice example of an amide bond.  And there is one major class of biological macromolecules where amide bonds are very, very important.  Perhaps the OP could focus on one of these groups of molecules.

[aHerraez]

The aromaticity of the bases may be even more important than the amide (or not) group, in discussing reactivity of the molecule.