Both uracil and thymine pair with adenine, but they differ in their chemical structure. Thymine has an additional methyl group (-CH3) attached to its pyrimidine ring, while uracil lacks this group.

This 1:1 ratio of A:T and G:C is crucial for maintaining the structure and stability of DNA. 5-Methylcytosine is a modified nucleobase formed by the enzymatic addition of a methyl group to the 5th ...