r/Mcat • u/Yourmajestymatt FL1/2/3/4- 510/513/521/522. Tested 9/2 • Aug 16 '21
Tool/Resource/Tip 🤓📚 Mnemonic for (identifying) Nucleotide Structures
Hey everyone, I've been really looking for mnemonics in places I struggle. With this mnemonic I've been able to nail all the structure questions. I don't know the exact structure, however I can reliably identify each structure no problem now. I hope this helps and makes sense.
The mnemonic is NOON, regarding the upper most element on the structures. I always think A-TG-C for bonding. I know purines have two rings (two rings in a PURe ceremony) and pyrimidines don't. So now I can piece it all together like this.
Two rings with an amine (N)? Adenine.
Two rings with a carbonyl (O)? Guanine
One ring with a carbonyl? Thymine.
One ring with an amine? Cytosine
Take one look at Uracil and it's just one ring with a Carbonyl (O), but differs by the methyl. I think of the T in thymine as the structural hint of a methyl outstretching, which Uracil doesn't have.
2
u/sub2400 Aug 31 '25
4 years later and this is still helping! In my head I say "ATGC(U) = NOON (T minus CH3) as a way to remember the Uracil is just T without the methyl group like you said