WHY ADENINE AND GUANINE ARE CALLED PURINES

Purines are a class of nitrogenous bases found in the nucleic acids DNA and RNA. They are also found in some other biomolecules, such as adenosine triphosphate (ATP), which is the energy currency of the cell. There are two purines that occur naturally in DNA and RNA: adenine (A) and guanine (G).

Structure of Purines

Purines have a double-ring structure, consisting of a six-membered ring fused to a five-membered ring. The six-membered ring is called the purine ring, and the five-membered ring is called the pyrimidine ring. The purine ring is numbered 1 through 9, and the pyrimidine ring is numbered 1' through 5'.

Purines in Nucleic Acids

In nucleic acids, purines are paired with pyrimidines via hydrogen bonds. Adenine pairs with thymine (T) in DNA and uracil (U) in RNA, while guanine pairs with cytosine (C) in both DNA and RNA. This base pairing is essential for the structure and function of nucleic acids.

Other Roles of Purines

In addition to their role in nucleic acids, purines are also involved in a variety of other cellular processes. For example, ATP is used as an energy source by cells. Purines are also involved in cell signaling and metabolism.

Naming of Purines

The name "purine" comes from the Latin word "purum," which means "pure." This is because purines were first isolated from uric acid, a substance that was once thought to be pure.

Conclusion

Purines are an important class of biomolecules that play a vital role in many cellular processes. They are found in nucleic acids, where they are essential for the structure and function of these molecules. Purines are also involved in energy metabolism and cell signaling.

Frequently Asked Questions

1. What are the two purines that occur naturally in DNA and RNA?

   • Adenine (A) and guanine (G)

2. What is the structure of purines?

   • Purines have a double-ring structure, consisting of a six-membered ring fused to a five-membered ring.

3. How do purines pair with pyrimidines in nucleic acids?

   • Adenine pairs with thymine (T) in DNA and uracil (U) in RNA, while guanine pairs with cytosine (C) in both DNA and RNA.

4. What other roles do purines play in cells?

   • Purines are also involved in energy metabolism and cell signaling.

5. Where does the name "purine" come from?

   • The name "purine" comes from the Latin word "purum," which means "pure."