Energy metabolism
How the cell draws energy from glucose and fat: glycolysis, lactic fermentation, the Krebs cycle, the respiratory chain and ATP synthase, beta-oxidation, gluconeogenesis and ketone bodies, with the clinical situations that reveal them.
- 39 cards
- 4 topics
- Free
The outline, topic by topic
Each topic is weighted the way the exam weighs it.
- Concepts
- The steps
- Scenarios
- Understand
A few cards from the deck
Glycolysis: what is it?
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The breakdown of glucose into two pyruvates in the cytosol, with a net gain of 2 ATP, without oxygen.
It is the only pathway available to the red cell.
From glucose to ATP with oxygen: which step comes after "Glucose"?
- Glycolysis in the cytosol
- Pyruvate
- Acetyl-CoA in the mitochondrion
- Krebs cycle
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Glycolysis in the cytosol
Glycolysis yields little ATP; full oxidation in the mitochondrion yields about thirty per glucose.
Lactic fermentation: what is it?
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The conversion of pyruvate to lactate when oxygen runs short, regenerating NAD⁺ to keep glycolysis going.
Lactate is then recycled by the liver.
Cyanide poisoning kills within minutes despite well-oxygenated blood. Why?
- It takes oxygen's place on haemoglobin
- It paralyses the breathing muscles
- It stops glycolysis in the cytosol
- It blocks the respiratory chain: cells can no longer use oxygen
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It blocks the respiratory chain: cells can no longer use oxygen
It inhibits the last complex, cytochrome c oxidase.
Krebs cycle: what is it?
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A series of reactions in the mitochondrial matrix that oxidises acetyl-CoA to CO₂ and produces NADH and FADH₂.
It is the crossroads of carbohydrates, fats and amino acids.
Why is oxygen essential for mitochondrial ATP production?
- It supplies the oxygen atoms of ATP's phosphates
- It oxidises glucose directly in the cytosol
- It is the final acceptor of the respiratory chain's electrons
- It turns ATP synthase by binding to it
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It is the final acceptor of the respiratory chain's electrons
Without it, the chain stops, NADH piles up and the Krebs cycle jams.