Nucleotide Metabolism | Degradation of Uric Acid

The video tutorial explores purine catabolism, focusing on the formation of uric acid and its degradation across different organisms. Humans and some primates excrete uric acid due to a nonfunctional urate oxidase gene, while other species like birds and reptiles lack the gene entirely. The tutorial details the enzymatic pathways involved in purine degradation, highlighting allantoin, urea, and ammonia as excretion products in various organisms. It contrasts purine catabolism with pyrimidine degradation, emphasizing the diversity of end products based on the organism's enzymatic arsenal.

What is the role of xanthine oxidase in purine degradation?

• It synthesizes purines from amino acids.

• It converts uric acid to ammonia.

• It degrades uric acid to allantoin.

• It converts xanthine to uric acid.

Why do humans excrete uric acid instead of allantoin?

• Humans have a functional urate oxidase gene.

• Humans excrete allantoin instead of uric acid.

• Humans have a nonfunctional urate oxidase gene.

• Humans lack the gene for urate oxidase.

Which organisms excrete uric acid due to the absence of the urate oxidase gene?

• Marine invertebrates

• Most mammals

• Birds, reptiles, and insects

• Humans and primates

What is the primary purine degradation product excreted by most mammals?

• Allantoate

• Ammonia

• Uric acid

• Allantoin

Which enzyme converts allantoin to allantoate in bony fishes?

• Allantoicase

• Urease

• Allantoinase

• Urate oxidase

What is the final purine degradation product excreted by amphibians?

• Uric acid

• Ammonia

• Allantoin

• Urea

Which organisms excrete ammonia as the final purine degradation product?

• Amphibians

• Birds and reptiles

• Marine invertebrates

• Most mammals