Purine Catabolism and Uric Acid

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What is the role of purines in the body?

They are the end products of catabolism of proteins

They are involved in the breakdown of ATP

They are responsible for the excretion of uric acid

They serve as essential building blocks for DNA, RNA, and ATP (correct)

What is the fate of uric acid in the human body?

It is broken down into ATP

It is excreted from the body through the kidneys (correct)

It is excreted from the body through the liver

It is converted to allantoin by the enzyme uricase

What is the significance of the enzyme uricase in some species?

It breaks down DNA into RNA

It is involved in the synthesis of proteins

It converts ATP to ADP

It converts uric acid to a more soluble compound (correct)

What is the difference between humans and some other species in terms of uric acid metabolism?

Humans lack the enzyme uricase, while other species have it Signup and view all the answers

What is the initial molecule formed in the first step of de novo purine synthesis?

Phosphoribose diphosphate (PRPP) Signup and view all the answers

Which enzyme is responsible for resynthesizing hypoxanthine and guanine to purine nucleotides?

Hypoxanthine–guanine phosphoribosyl transferase (HGPRT) Signup and view all the answers

What is the primary function of the de novo synthesis pathway?

Forming complex molecules from simple molecules such as amino acids and ribose-5-phosphate Signup and view all the answers

What is the source of the purine molecules that are resynthesized in the salvage pathway?

RNA and DNA degradation Signup and view all the answers

What percentage of urate produced in the body is excreted in the urine?

70% Signup and view all the answers

What is the term for the breakdown of urate by intestinal bacteria in the gut?

Uricolysis Signup and view all the answers

Hyperuricemia can occur due to which of the following mechanisms?

Increased production and decreased excretion Signup and view all the answers

What is the fate of the remaining 30% of urate produced in the body?

It is broken down by intestinal bacteria Signup and view all the answers

Which genetic disorder is characterized by a deficiency in the salvage pathway of purine nucleotide synthesis?

HGPRT deficiency Signup and view all the answers

What is the primary effect of thiazide diuretics on uric acid levels?

Decreased urate secretion Signup and view all the answers

Which dietary factor is likely to contribute to hyperuricemia due to excessive purine intake?

High meat and seafood intake Signup and view all the answers

What is the primary mechanism by which myeloproliferative disorders contribute to hyperuricemia?

Increased production of uric acid Signup and view all the answers

What is the primary effect of lactate or ketoacid excess on uric acid levels?

Decreased elimination of uric acid Signup and view all the answers

Which of the following dietary factors is likely to contribute to hyperuricemia due to excessive purine intake?

Purine-rich diet Signup and view all the answers

What is the primary cause of gout?

Increased synthesis of purine nucleotides Signup and view all the answers

What is the characteristic of primary gout?

It is an inborn error of metabolism of purine Signup and view all the answers

What is the complication of gout besides inflammation, pain, and the development of tophi?

Urolithiasis Signup and view all the answers

What is the difference between primary and secondary gout?

Primary gout is an inborn error of metabolism, while secondary gout is caused by various diseases Signup and view all the answers

What is the characteristic of monosodium urate crystals in gout?

They are formed when serum urate levels exceed the solubility limit Signup and view all the answers

What is the primary method of diagnosing gout and pseudogout?

Identifying characteristic crystals in synovial fluid Signup and view all the answers

What is the relationship between hyperuricemia and gout?

Hyperuricemia can lead to gout, but it is not a guaranteed outcome Signup and view all the answers

What is the significance of joint aspiration in diagnosing gout and pseudogout?

It provides access to synovial fluid for crystal identification Signup and view all the answers

What is the primary benefit of examining synovial fluid in the diagnosis of gout and pseudogout?

It enables the identification of characteristic crystals Signup and view all the answers

What is the effect of allopurinol on uric acid levels in the blood?

Decreases uric acid levels Signup and view all the answers

Which of the following conditions is characterized by an enzymatic defect in the urate pathway?

Hereditary xanthinuria Signup and view all the answers

What is the normal plasma level of uric acid in females?

2.4 - 6 mg/dL Signup and view all the answers

Which of the following substances can cause a falsely decreased uric acid level in a blood test?

Bilirubin Signup and view all the answers