Adenine may also be named 6-amino purine. How would you name the other four nitrogenous bases, using this alternative system? (O is indicated by 'oxy-,' and CH₃ by 'methyl.')

Verified step by step guidance

1. Understand that adenine is named 6-amino purine because it has an amino group (–NH₂) attached to the 6th carbon of the purine ring. This naming system focuses on the functional groups attached to the purine or pyrimidine ring.
2. Identify the base type for each nitrogenous base: guanine and adenine are purines (two-ring structures), while cytosine, thymine, and uracil are pyrimidines (single-ring structures).
3. For guanine, note that it has an amino group at position 2 and an oxygen (oxo group) at position 6 on the purine ring. Using the alternative system, name it as 2-amino-6-oxy purine.
4. For cytosine, which is a pyrimidine, it has an amino group at position 4 and an oxygen at position 2. Name it as 4-amino-2-oxy pyrimidine.
5. For thymine and uracil, both are pyrimidines with oxygen atoms at positions 2 and 4. Thymine has an additional methyl group at position 5. Name uracil as 2,4-dioxy pyrimidine and thymine as 5-methyl-2,4-dioxy pyrimidine.

Key Concepts

Nitrogenous Base Structure and Classification

Nitrogenous bases are organic molecules that form the building blocks of nucleic acids. They are classified into purines (adenine and guanine) with a double-ring structure, and pyrimidines (cytosine, thymine, uracil) with a single-ring. Understanding their chemical structure is essential for systematic naming based on functional groups.

Functional Group Nomenclature in Nitrogenous Bases

The alternative naming system uses functional groups like amino (-NH2), oxy (=O), and methyl (-CH3) to describe nitrogenous bases. For example, adenine is 6-amino purine, indicating an amino group at position 6 on the purine ring. Recognizing these groups and their positions allows systematic naming of other bases.

Position Numbering in Purine and Pyrimidine Rings

Purine and pyrimidine rings have standardized numbering systems to identify the location of substituents. For purines, numbering starts at the nitrogen in the six-membered ring, while for pyrimidines, numbering begins at the nitrogen in the ring. Correct numbering is crucial for accurately naming functional groups on the bases.