tricarboxylic acid cycle
Let an agent explain the tricarboxylic acid cycle and its steps, relay its role in energy metabolism and biosynthesis from biochemistry references, describe regulation and the reductive variant, and distinguish it from glycolysis and oxidative phosphorylation.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
written by Claude from model knowledge without web access - no source was read, every claim is a lead to verify
Researched by: Claude
Purpose and description
Let an agent explain the tricarboxylic acid cycle and its steps, relay its role in energy metabolism and biosynthesis from biochemistry references, describe regulation and the reductive variant, and distinguish it from glycolysis and oxidative phosphorylation.
A central metabolic pathway, also called the citric acid cycle or Krebs cycle, in which acetyl-CoA derived from carbohydrates, fats and proteins is oxidised in the mitochondrial matrix of eukaryotes or the cytoplasm of prokaryotes through a series of eight enzymatic steps to carbon dioxide, generating NADH, FADH2 and GTP that feed oxidative phosphorylation, and supplying intermediates for biosynthesis; some bacteria and archaea run the reductive tricarboxylic acid cycle in reverse to fix carbon dioxide.
What it is for: Not applicable; a metabolic pathway.
It can be explain the steps; relay role in metabolism; describe regulation and variants; distinguish from linked pathways.
Distinguishing features
Cyclic pathway
Hub of metabolism
Electron carrier production
Amphibolic role
What it looks like
Not a visible object; a cyclic pathway of reactions.
Physical character
steps: 8 count
yield per acetyl-CoA: 3 NADH, 1 FADH2, 1 GTP products
described: 1937 year - Hans Krebs
How it is recognised
Citric acid or Krebs cycle
Eight-step oxidative cycle; reductive TCA cycle in some prokaryotes
Glycolysis precedes it; oxidative phosphorylation uses its products; the glyoxylate cycle is a variant in plants and microbes
Related models
is a kind of - in registry terms
takes place in - in eukaryotes
follows - via pyruvate dehydrogenase
feeds - with NADH and FADH2
In practice
Families and kinds
oxidative tricarboxylic acid cycle in mitochondria and prokaryotes
reductive tricarboxylic acid cycle for carbon fixation
glyoxylate cycle as a variant
anaplerotic and cataplerotic reactions feeding and draining the cycle
incomplete cycles in some organisms
Identifiers
GO GO:0006099 tricarboxylic acid cycle
KEGG map00020 citrate cycle
Standards and regulation
No regulation; standard biochemical definitions
Gene Ontology and pathway database annotations
Failure modes and hazards
Confusing the cycle with glycolysis or the electron transport chain
Miscounting ATP yields
Oversimplifying regulation
Also called
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 4 bundles · 8 layers · 8 findings · 16 questions.
Understand What the TCA cycle is.
Science.
Definition
Definition and steps.
Definition
Definition.
- What is the tricarboxylic acid cycle, and what happens in each of its eight steps? definition
- Is the question about the TCA cycle, glycolysis, oxidative phosphorylation or the glyoxylate cycle? boundary
Inputs
Inputs and outputs.
Inputs
Inputs.
- How does acetyl-CoA enter, and what are the products and energy yield? definition
- Which entry fits the specific enzyme or intermediate? action
Role Role in metabolism.
Science.
Energy
Energy metabolism.
Energy
Energy.
- How does the cycle link carbohydrate, fat and protein breakdown to ATP production? provenance
- Which references are standard? provenance
Biosynthesis
Biosynthesis and anaplerosis.
Biosynthesis
Biosynthesis.
- How do cycle intermediates supply biosynthesis, and how do anaplerotic reactions replenish them? provenance
- Which entry fits anaplerotic reaction? action
Regulate Regulation and variants.
Science.
Regulation
Regulation.
Regulation
Regulation.
- How is the cycle regulated by energy status, substrates and allosteric control? provenance
- Which sources are cited? provenance
Variants
Reductive and glyoxylate cycles.
Variants
Variants.
- How does the reductive TCA cycle fix carbon in some prokaryotes, and how does the glyoxylate cycle differ? provenance
- Which entry fits reductive TCA cycle? action
Context Medicine and history.
Context.
Medicine
Medicine.
Medicine
Medicine.
- What diseases involve TCA cycle enzymes, and how do oncometabolites arise, in general terms? provenance
- Which entry fits inborn errors of metabolism? action
History
History.
History
History.
- How did Krebs and others elucidate the cycle, and why was it Nobel-recognised? provenance
- Which entry fits the history of biochemistry? action
What the second pass must settle
- Should the reductive cycle and the glyoxylate cycle be separate entries?
- How should biochemistry references be linked?
- How should inherited enzyme defects be linked?