Problem 8 - Biochemistry

Question

What is the primary metabolic fate of excess purine nucleotides in humans, Siberian tigers, flamingos, rattlesnakes, tuna, great white sharks, salamanders, cockroaches, and lobsters?

Step-by-Step Solution

Answer

Answer: The primary metabolic fate of excess purine nucleotides in these organisms is as follows: Uric acid in humans, Siberian tigers, flamingos, rattlesnakes, and cockroaches; Ammonia in tuna, great white sharks, and lobsters; and Urea in salamanders.

Step 1: Understand purine nucleotides

Purine nucleotides are the precursors of the purine bases adenine and guanine, which are essential components of nucleic acids (DNA and RNA). The metabolism of purine nucleotides involves de novo synthesis, salvage pathways, and degradation.

Step 2: Metabolic fate of excess purine nucleotides

When there is an excess of purine nucleotides in an organism, they are generally degraded. The primary metabolic fate of excess purine nucleotides is their conversion to uric acid in humans and most other mammals, while in some other organisms, they are converted to ammonia or urea.

Step 3: Identifying primary metabolic fate in each organism

1. Humans: Excess purine nucleotides are converted to uric acid in human metabolism. 2. Siberian tigers: As mammals, Siberian tigers also metabolize excess purine nucleotides into uric acid. 3. Flamingos: Being birds, flamingos excrete excess purine nucleotides in the form of uric acid. 4. Rattlesnakes: Reptiles, like rattlesnakes, convert excess purine nucleotides to uric acid for excretion. 5. Tuna: As fish, tuna primarily convert excess purine nucleotides into ammonia for excretion. 6. Great white sharks: Similar to other fish, great white sharks convert purine nucleotides to ammonia. 7. Salamanders: Being amphibians, salamanders convert excess purine nucleotides to urea for excretion. 8. Cockroaches: As insects, cockroaches primarily metabolize excess purine nucleotides into uric acid. 9. Lobsters: Crustaceans like lobsters excrete excess purine nucleotides as ammonia. Summary: Uric acid: Humans, Siberian tigers, flamingos, rattlesnakes, and cockroaches Ammonia: Tuna, great white sharks, and lobsters Urea: Salamanders