* Adenine (A)

* Guanine (G)

* Cytosine (C)

* Uracil (U)

Base Pairing in RNA:

Adenine (A) always binds to Uracil (U) through two hydrogen bonds.

Guanine (G) always binds to Cytosine (C) through three hydrogen bonds.

This base pairing is essential for the structure and function of RNA:

* RNA Structure: The complementary base pairing helps form the characteristic double helix structure of some RNA molecules, like tRNA.

* RNA Function: The base pairing is crucial for the process of protein synthesis. In mRNA, the codons (sequences of three bases) are recognized by complementary anticodons on tRNA, which carry specific amino acids. This pairing ensures the correct sequence of amino acids is incorporated into the growing polypeptide chain.

Key Differences from DNA:

* RNA uses Uracil (U) instead of Thymine (T) which is found in DNA.

* RNA is typically single-stranded while DNA is double-stranded.

Let me know if you have any other questions!