Anaerobic Respiration Flashcards
What is the purpose of anaerobic respiration?
It releases energy from substrates (glucose/proteins) without using oxygen in the CYTOPLASM
What happens if there isn’t oxygen at the end of the ETC?
- Electrons will stop moving through the ETC, meaning there will be no proton gradient so chemiosmosis can’t happen.
- Reduced NAD/FAD can’t be oxidised so the levels of NAD and FAD are low; all respiration reactions need NAD so ATP isn’t made in any reaction.
How is reduced NAD oxidised in plants and fungi?
The ethanol fermentation pathway reoxidises reduced NAD.
- Pyruvate is decarboxylated to ETHANAL (by enzyme pyruvate dehydrogenase).
- Ethanal accept a hydrogen ion (acts as oxygen) producing ethanol.
Ethanal + H —-> ethanol + oxidised NAD
How is reduced NAD oxidised in mammals?
The lactate fermentation pathway is used in muscle tissue where there’s a high ATP demand for muscle contractions but an oxygen deficit.
Pyruvate accepts a hydrogen ion (acts as oxygen) from reduced NAD, forming lactate.
pyruvate + H —-> lactate + oxidised NAD
What does glycolysis produce in anaerobic conditions?
2 ATP
2 reduced NAD
2 pyruvate
Why does lactate fermentation occur?
Happens in exercise where there are more muscle contractions, producing high ATP demands but with an oxygen deficit.
PYRUVATE is the HYDROGEN ACCEPTOR from reduced NAD, oxidising it (since there isn’t enough oxygen to act as the final electron acceptor).
The enzyme lactate dehydrogenase catalyses the oxidation of reduced NAD.
This allows glycolysis to generate ATP.
The reaction of pyruvate + reduced NAD produces lactate acid and H ions.
What happens to the lactate acid?
Lactate is acidic so is transported to the liver where its oxidised to pyruvate (oxygen is needed for this so people breath heavily after exercise).
The movement of lactate in the blood lowers its pH, reducing nervous stimulation from the CNS which will then reduce muscle contractions (rest and relax).
Compare the production of ATP in aerobic and anaerobic respiration.
Aerobic produces 31 ATP per glucose.
Anaerobic produces 2 ATP per glucose.
