krebs urea cycle
C2Technical / Academic / Scientific
Definition
Meaning
A specific cyclic metabolic pathway that converts nitrogenous waste into urea for excretion.
A fundamental biochemical process occurring in the liver, also known as the ornithine cycle, where ammonia is combined with carbon dioxide to form urea, preventing toxic buildup.
Linguistics
Semantic Notes
This is a proper noun for a specific metabolic cycle. Often called simply the 'urea cycle'. 'Krebs' refers to Hans Krebs, who described it, and distinguishes it from the 'Krebs cycle' (citric acid cycle) for energy production.
Dialectal Variation
British vs American Usage
Differences
No difference in the term itself. Potential variation in pronunciation of 'urea' (/jʊˈriːə/ vs. /jʊˈriə/).
Connotations
None; purely scientific.
Frequency
Used identically and with identical frequency in scientific contexts in both regions.
Vocabulary
Collocations
Grammar
Valency Patterns
[The] Krebs urea cycle + VERB (converts, occurs, functions)[Subject] + is + regulated/diagrammed/described + by the Krebs urea cycleVocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “[Not applicable for this technical term]”
Usage
Context Usage
Academic
Essential term in biochemistry, physiology, and medical textbooks.
Technical
Central concept in discussions of liver function, metabolic disorders (e.g., hyperammonemia), and nitrogen balance.
Examples
By CEFR Level
- The body removes harmful ammonia using the Krebs urea cycle.
- A malfunction in the Krebs urea cycle can cause dangerous levels of ammonia in the blood.
- The hepatic Krebs urea cycle is intricately regulated by substrate availability and allosteric modulation of its key enzymes, such as carbamoyl phosphate synthetase I.
Learning
Memory Aids
Mnemonic
Think: 'Krebs Uses Really Efficient Actions' to turn toxic ammonia into Urea.
Conceptual Metaphor
A waste disposal/recycling plant for nitrogen in the body.
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Do not confuse with 'цикл Кребса' which typically refers to the citric acid cycle. Specify 'цикл мочевины Кребса' or 'орнитиновый цикл'.
- Ensure 'urea' is translated as 'мочевина', not simply 'моча' (urine).
Common Mistakes
- Calling it the 'Krebs cycle' without 'urea', leading to confusion with the citric acid cycle.
- Incorrect pronunciation of 'Krebs' as /kriːbz/ (should be /krebz/).
- Treating it as a general term instead of a proper noun (often not capitalised correctly).
Practice
Quiz
What is the primary nitrogenous end product of the Krebs urea cycle?
FAQ
Frequently Asked Questions
No. They are two distinct cycles discovered by Hans Krebs. The Krebs urea cycle (ornithine cycle) produces urea in the liver. The Krebs cycle (citric acid cycle) produces energy in mitochondria.
It begins in the mitochondria and is completed in the cytoplasm of liver cells (hepatocytes).
It converts highly toxic ammonia, a byproduct of protein metabolism, into less toxic urea, which can be safely excreted by the kidneys.
It leads to hyperammonemia, a buildup of ammonia in the blood, which is neurotoxic and can cause brain damage, coma, or death if untreated.