The crystalline compound that is a product of protein metabolism is known as ___________.
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A
uracil
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B
urine
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C
ureter
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D
urea
Urea is the nitrogenous crystalline compound produced during protein catabolism.
Its a primary waste product of amino acid deamination excreted in urine.
A) uracil
Uracil is a pyrimidine nucleobase in RNA, genetic coding molecule unrelated to protein waste metabolism. While both contain "ur-" prefixes relating to urine (where first isolated), uracil functions in nucleic acids; urea functions in nitrogen excretion, distinct biochemical roles.
B) urine
Urine is the liquid excretory product containing urea, vehicle rather than compound itself. Urea constitutes urine's primary nitrogenous solute (~9g/L), but urine includes water, salts, creatinine, making this option confuse solution with solute.
C) ureter
Ureters are muscular tubes transporting urine from kidneys to bladder, conduit structures rather than chemical compounds. This confuses anatomical pathway with metabolic product, categorical error between structure and substance.
D) urea
Urea precisely matches the description: crystalline compound (melting point 133°C) produced from ammonia detoxification during protein metabolism, excreted renally as primary nitrogenous waste. Its chemical formula CO(NH₂)₂ and role in urea cycle establish it as the definitive answer.
Conclusion
Urea constitutes the primary nitrogenous waste product of protein metabolism, crystalline compound formed in liver via urea cycle to detoxify ammonia from amino acid catabolism. Unlike uracil (nucleobase), urine (excretory fluid), or ureter (anatomical conduit), urea alone captures the specific crystalline metabolic end-product central to nitrogen homeostasis.
Topic Flashcards
Click to FlipWhat is the name of the biochemical cycle in the liver that produces urea from ammonia?
The urea cycle (or ornithine cycle).
What is uric acid?
A different nitrogenous waste product produced from the breakdown of purines (found in DNA/RNA and some foods), excreted in urine and associated with gout.
What is creatinine?
A waste product from muscle metabolism that is filtered by the kidneys and measured in blood/urine tests to assess kidney function. It is related to, but distinct from, urea.
What is BUN a common medical abbreviation for?
Blood Urea Nitrogen. It is a standard blood test that measures the amount of nitrogen in the blood that comes from urea, used to evaluate kidney function.
What is the primary nitrogenous waste product in human urine, resulting from protein breakdown?
Urea