Question

What are the $2$ purine bases and the $2$ pyrimidine bases?

Answer 1

Let us first of all understand what purines and pyrimidines are. Two types of nitrogen-containing bases are purines and pyrimidines. Purines are made up of a six-membered nitrogen-containing ring fused to a five-membered nitrogen-containing ring. Pyrimidines feature a nitrogen-containing ring with only six members. We are concerned about four purines and four pyrimidines.

Complete answer:
Purine is a nitrogen-based compound with two carbon-nitrogen rings and four nitrogen atoms. The melting point of purines is rather high.
Pyrimidines have one carbon-nitrogen ring and two nitrogen atoms in their structure. Their melting point is low.
Purine bases include the following:
Adenine = $6$-amino purine
Guanine = $2$-amino-$6$-oxy purine
Hypoxanthine = $6$-oxy purine
Xanthine = $2$,$6$-dioxy purine
Both DNA and RNA include adenine and guanine. Hypoxanthine and xanthine are not absorbed into nucleic acids during synthesis, although they are crucial stages in purine nucleotide synthesis and breakdown.
Pyrimidine bases include the following
Uracil = $2$,$4$-dioxy pyrimidine
Thymine = $2$,$4$-dioxy-$5$-methyl pyrimidine
Cytosine = $2$-oxy-$4$-amino pyrimidine
Orotic acid = $2$,$4$-dioxy-$6$-carboxy pyrimidine
So, two purine bases can be named as Adenine and Guanine. And, two pyrimidine bases can be named as Cytosine and Uracil.

Note:
It can be noted that a nucleoside is a chemical formed when a sugar, such as ribose or 2-deoxyribose, is joined to a nitrogen base.Purine nucleosides have names that end in-osine, while pyrimidine nucleosides have names that finish in-idine. Also, both DNA and RNA include cytosine. Uracil can only be present in RNA. Thymine is a type of nucleotide that is generally found in DNA. Thymine and uracil are sometimes found together in tRNA.