Question

Is cytosine a purine (or) a pyrimidine? How can you tell?

Answer 1

We have to know that Cytosine is one of the four primary bases found in DNA and RNA, alongside adenine, guanine, and thymine (uracil in RNA). It was founded by Albrecht Kossel and Albert Neumann. We can find cytosine in part of the DNA (or) portion of RNA (or) part of the nucleotide. We have to know that the chemical formula of cytosine is ${C_4}{H_5}{N_3}O$. We have to know that the molar mass of cytosine is $111.10g/mol$.

Complete step by step answer:
We have to know that Purine is a heterocyclic fragrant natural compound made out of a pyrimidine ring fused with an imidazole ring. It includes adenine and guanine as nucleobases. It comprises two hydrogen-carbon rings and four atoms of nitrogen. Catabolism brings about the creation of uric acid.
Pyrimidine is a heterocyclic sweet-smelling natural compound that is made out of carbon and hydrogen. It contains Cytosine, thymine, uracil as nucleobases. It comprises one hydrogen-carbon ring and two atoms of nitrogen. Catabolism produces carbon dioxide, beta-amino acids and ammonia.
We could draw the structure of cytosine is,

We have to know that cytosine is a derivative of pyrimidine. It contains heterocyclic aromatic ring and two substituents are attached. One substituent is an amino group at fourth position and a keto group is present at the second position. The nucleoside of cytosine is cytidine.
Cytosine could be paired with guanine in RNA and in DNA. It is inherently unstable and could change in uracil.

Note: We have to know that in Watson-Crick base pairing, cytosine could form three hydrogen bonds with guanine. We have to know that the IUPAC name of cytosine is 4-aminopyrimidin-2(1H)-one. We have to know that the nucleoside of cytosine is cytidine. Cytosine could also be methylated into 5-methylcytosine by an enzyme known as DNA methyltransferase.