krebs cycle
C1/C2Scientific, Academic, Technical
Definition
Meaning
A series of biochemical reactions in aerobic organisms that releases energy from food molecules, mainly carbohydrates, fats, and proteins, producing carbon dioxide and ATP.
The central metabolic pathway in cellular respiration where acetyl-CoA is oxidized, generating high-energy electron carriers (NADH, FADH₂) and ATP precursors. It is a cyclical process within the mitochondrial matrix, crucial for energy production.
Linguistics
Semantic Notes
Often synonymous with 'citric acid cycle' or 'tricarboxylic acid (TCA) cycle.' The term emphasizes its discoverer, Sir Hans Krebs, while 'citric acid cycle' focuses on its key intermediate.
Dialectal Variation
British vs American Usage
Differences
No significant differences in meaning or usage. 'Krebs cycle' is the dominant term in both varieties. Pronunciation follows typical BrE/AmE patterns for the word 'cycle'.
Connotations
Neutral scientific term in both varieties.
Frequency
Equally standard and high-frequency in biological contexts in both BrE and AmE.
Vocabulary
Collocations
Grammar
Valency Patterns
The Krebs cycle occurs in [location].[Molecule] enters the Krebs cycle.The Krebs cycle produces [product].The Krebs cycle is also known as [synonym].Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “[Not applicable for this technical term]”
Usage
Context Usage
Business
[Not applicable]
Academic
A fundamental concept in biochemistry, physiology, and cell biology modules.
Everyday
Virtually never used outside educational or scientific contexts.
Technical
Core terminology in medical, biological, and biochemical research, lab reports, and textbooks.
Examples
By Part of Speech
verb
British English
- [Not applicable as a verb]
American English
- [Not applicable as a verb]
adverb
British English
- [Not applicable as an adverb]
American English
- [Not applicable as an adverb]
adjective
British English
- Krebs-cycle intermediates are key metabolic regulators.
- The Krebs-cycle activity was measured.
American English
- Krebs cycle enzymes are located in the mitochondrial matrix.
- The Krebs cycle pathway is highly conserved.
Examples
By CEFR Level
- [This term is too advanced for A2 level.]
- The Krebs cycle is a part of how our cells make energy.
- It happens inside tiny parts of the cell called mitochondria.
- Understanding the Krebs cycle is essential for grasping cellular respiration.
- The cycle begins when acetyl-CoA combines with oxaloacetate to form citrate.
- Disruption of the Krebs cycle, through enzyme deficiencies, can lead to severe metabolic disorders.
- The reducing equivalents NADH and FADH₂, generated by the Krebs cycle, are subsequently used in oxidative phosphorylation.
Learning
Memory Aids
Mnemonic
Citrate Is Krebs Starting Substrate: C (Citrate) I (Isocitrate) K (α-Ketoglutarate) S (Succinyl-CoA) S (Succinate) F (Fumarate) M (Malate) O (Oxaloacetate).
Conceptual Metaphor
A circular production line (cycle) in a power plant (mitochondrion) that processes fuel (acetyl-CoA) to generate electricity (ATP) and exhaust (CO₂).
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Avoid direct translation of 'cycle' as 'цикл' without the proper name 'Цикл Кребса' or 'Цикл трикарбоновых кислот'.
- Do not confuse with the 'Calvin cycle' (темновая фаза фотосинтеза) which is in plants.
Common Mistakes
- Incorrectly calling it the 'Kreb cycle' (missing the 's').
- Confusing its location (mitochondrial matrix) with glycolysis (cytoplasm).
- Stating it requires oxygen directly (it requires the *products* of aerobic processes).
Practice
Quiz
Where does the Krebs cycle take place in a eukaryotic cell?
FAQ
Frequently Asked Questions
Sir Hans Adolf Krebs, a German-born British biochemist, for which he received the Nobel Prize in Physiology or Medicine in 1953.
Yes, they are synonymous terms. 'Krebs cycle' is named after its discoverer, while 'citric acid cycle' refers to the first product formed in the cycle.
One ATP (or GTP, depending on the organism) is produced directly per turn. However, the cycle's main energy yield is in the form of high-energy electron carriers (NADH and FADH₂) which drive the production of many more ATP molecules later.
Because it regenerates its starting molecule, oxaloacetate, at the end of the series of reactions, allowing the process to continue anew with another acetyl-CoA molecule.