Identify each of the following as a purine or a pyrimidine:
a. guanine

Verified step by step guidance

1. Understand the difference between purines and pyrimidines: Purines are larger, double-ring structures, while pyrimidines are smaller, single-ring structures. This distinction is key to identifying the type of nitrogenous base.
2. Recall the specific bases classified as purines: Adenine (A) and Guanine (G) are purines. Cytosine (C), Thymine (T), and Uracil (U) are pyrimidines.
3. Examine the given base, guanine. Based on the classification, guanine is one of the purines because it has a double-ring structure.
4. Visualize or refer to the molecular structure of guanine to confirm its double-ring characteristic, which is a hallmark of purines.
5. Conclude that guanine is a purine based on its structural features and classification in nucleic acids.

Key Concepts

Purines and Pyrimidines

Purines and pyrimidines are the two categories of nitrogenous bases found in nucleic acids. Purines, which include adenine and guanine, have a double-ring structure, while pyrimidines, such as cytosine, thymine, and uracil, have a single-ring structure. This distinction is crucial for understanding the structure of DNA and RNA, as these bases pair specifically during the formation of nucleic acid strands.

Guanine

Guanine is one of the four main nucleobases in the nucleic acid DNA and RNA. It is classified as a purine due to its double-ring structure. Guanine pairs with cytosine in DNA and RNA, forming stable hydrogen bonds that are essential for the integrity of the genetic code. Its role is vital in various biological processes, including protein synthesis and cellular signaling.

Base Pairing

Base pairing refers to the specific hydrogen bonding between nitrogenous bases in DNA and RNA. In DNA, adenine pairs with thymine, and guanine pairs with cytosine, while in RNA, adenine pairs with uracil instead of thymine. This complementary pairing is fundamental for the accurate replication of genetic material and the transcription process, ensuring that genetic information is correctly conveyed during cell division and protein synthesis.