Uric acid is the final breakdown product of which two purines?

Uric acid is indeed the final breakdown product of the purines adenine and guanine. These purines are essential components of nucleic acids and are involved in various metabolic processes within the body. When purines are broken down, they go through a series of steps which ultimately lead to the production of uric acid.

Adenine and guanine are two of the four nucleobases found in nucleic acids, and they undergo deamination and other enzymatic reactions that convert them into uric acid. This is particularly important in humans and many other organisms, as uric acid plays a role in the regulation of nitrogen balance and is excreted through urine.

The other options, which contain pyrimidines (like uracil, thymine, cytosine, and uridine), do not contribute to the synthesis of uric acid in the same manner as purines do. Pyrimidines are broken down differently and ultimately result in different end products such as beta-alanine and ammonia instead of uric acid. Understanding these distinctions highlights the metabolic pathways and the significance of purine and pyrimidine metabolism in biological systems.